ABSTRACT

The aim of the course of the Building Construction I is to familiarize students with the technical terminology and basic functional, structural and architectural requirements. Basic knowledge of the areas of foundations, substructures, vertical load-bearing structures, dilations and building construction systems are presented. After completing the subject, the ability to apply the knowledge from the above-mentioned topics to practice is assumed.

REFERENCES

• MATOUŠOVÁ, D., SOLAŘ, J., Pozemní stavitelství I. 1. vyd. Ostrava: VŠB TU, 2005. ISBN 80-248-0830-7. [in Czech]
• LORENZ, K. Nosné konstrukce I. Základy navrhování nosných konstrukcí. 1. vyd. Praha: ČVUT, 2005. ISBN 80-01-03168-3. [in Czech]
• NESTLE, H. a kol. Moderní stavitelství pro školu i praxi. Praha: Sobotáles, Praha, 2005. ISBN:80-86706-11-7. [in Czech]
• HANÁK, M. Pozemní stavitelství: cvičení I. 6. přeprac. vyd. Praha: ČVUT, 2005. ISBN 80-01-03267-1 [in Czech]
• HÁJEK, P. a kol. Konstrukce pozemních staveb 1. Nosné konstrukce I. 3. vyd. Praha: ČVUT, 2007. ISBN 978-80-01-03589-4. [in Czech]

CHAPTERS

1. Introduction to Building Construction
2. Construction System
3. Construction System of Multi-storeys Buildings
4. Construction System of Hall Buildings
5. Dilatation of Buildings
6. Basic Soil and Earthworks
7. Shallow Foundations
8. Deep Foundations
9. Load Bearing Masonry Constructions
10. Monolithic and Prefabricated Vertical Structures
11. Openings in Walls
12. Chimneys

BASIC TERMINOLOGY

Civil engineering means the art of construction or science or the constructional doctrine. Building engineering is often confused with word architecture, although building engineering concerns mainly to structures while architecture predominantly deals with a form.

Building construction is the production sector, which is focused to survey, design and construction work, as well as renovation and maintenance of buildings and the final results are the finished buildings.

Architecture is, in the narrower sense, a building art that produces works that, in their shape and space, correspond to the practical purpose and the ideological requirements of the times, and the individual building that appears to be the architectural design. In the widest contemporary conception, architecture also includes the formation of the entire environment by artistic means in connection with available scientific knowledge.

The construction is a summary of supplies of building materials, materials, parts and works, often machines, equipment used to create a work on the basis of relevant documentation, and is generally firmly connected to the ground.

Building structures can be defined as structures, whose larger part is located on the earth's surface. The ground structures include buildings for housing, civic buildings (health care buildings, school buildings, sports buildings, cultural buildings, services and trade, construction sites for transport, administrative buildings, ...), industrial (production halls, workshops, warehouses, etc.) and agricultural buildings (stables, haymakers, greenhouses, ...).

Building object is spatially coherent or technically individual purpose-built part of the construction. The most common form of a building object is a building, a bridge or a road.

The building is a set of building structures creating a spatial structure. The building structure must fulfill the required function.

Due to the limited physical and moral life of the buildings, besides realization of production and non-production buildings, another task is also maintenance, modernization and reconstruction of the buildings:

• Maintenance reduces the degree of degradation of structural elements, usually involves the renewal of protective surface coating.
• Modernization is an increase in the utility value of a building or its part without changing the purpose. The goal is to improve the standard of use.
• Reconstruction is to restore an object or its part into the original condition with the utmost emphasis on preserving the original appearance and design solution.

The basic objective of the building activity is to create a quality environment for the purpose for which the object is designed, while the quality should be ensured for the entire expected life of the building.

Basic requirements for building construction:

• Architectural requirements:
  • Urbanistic requirements: Requirements for the structure and development of municipalities, intensity of land use and location of buildings.
  • Operational Requirements: Disposition (typological) requirements, divided and interconnected spaces, communication links.
  • Aesthetic requirements: Shaping of the whole and its parts, color solution, monument care.
• General requirements for building safety and use:
  • Mechanical resistance and stability
  • Fire safety
  • Health protection of persons, animals and healthy living conditions and the environment
  • Protection against noise and vibrations
  • Building safety
  • Energy saving and thermal protection
• Resistance to external influences
• Requirements for the well-being and quality of the indoor environment
• Technology requirements
• Economic requirements
• Environmental requirements

Modular coordination or dimensional unification ensures consistency between the dimensions of the building and its building components. This is a set of rules for determining the compositional dimensions of objects and elements. Basic rules for modular co-ordination of dimensions in construction are laid down in ČSN 73 005 (1990).

The module, labelled M, is the agreed length unit used to determine and coordinate dimensions in construction. Depending on the spatial layout, the ground module and the height module are distinguished.

The basic (metric) module in the construction is equal to M = 100 mm. Until 1960, a 150 mm module was used. In accordance with EU regulations, the 125 mm module can also be used.

The derived modules are multiples or fractions of the base module:

• The enlarged module (200, 300, 500, 3000 and 6000 mm) is used as ground plan dimensions, ie the distance of walls, columns, pillars, etc.
• The reduced module (50, 20, 10, 5, 2 and 1 mm) is used, for example, for coordinate dimensions of the cross-section of building elements (columns, walls, beams, boards, etc.). Values of 20 mm or less are used to determine thicknesses of thin-walled elements.

The composability is a property of spatial parts of objects that allow them to be sorted, assembled, and deployed without the need to change or adapt their dimensions and shape. The dimensions of the construction elements must allow their mutual assembly to the larger assemblies.

• The coordinate (dimensional) dimension of the element is the dimension that the element occupies theoretically in the modular space network of the structure, i.e. including the relevant part of the joint, eg burnt bricks 150 x 75 x 300 mm.
• The basic dimension (formerly production dimension) of the elements is the size prescribed for the element production, assuming a zero tolerance. The basic dimension of the element is smaller than the composite dimensional dimension, eg burnt bricks 140 x 65 x 290 mm.

Prescribed basic (production) dimensions are technically impossible to always observe. The actual dimensions of the manufactured elements may differ from the prescribed basic (production) dimensions by the tolerance allowed (deviation).

TYPIFICATION AND PREFABRICATION IN CONSTRUCTION

Typification is a process aimed at selecting a limited number of system building elements and technologies. Its goal is to reduce recurrent solutions, accelerate and increase the economic efficiency of construction. Typification is the unification of dimensions in the construction industry. Typification is used for individual elements or for whole objects:

• Elemental typification includes the manufacture of individual building components, such as ceiling panels windows, all of which are then assembled structures. The condition for their reusability is compliance coordination module dimensions.
• Object typification involves the complex solution of whole building structures or parts thereof, eg apartment buildings. The advantage of volume typing is the economy of construction. The disadvantage is uniformity and low variability.

Dimension unification allows universal use of the same elements mass-produced for different purposes.

Prefabrication is the production of structural components or parts thereof outside the site of their use (site). The individual prefabricated pieces are then brought to the construction site from the factory and the actual construction of the rough construction takes the form of assembly of the individual part

Keywords: Construction system, load-bearing structure, non-load-bearing structure, stability, floor (storey), tract, headroom

CHARACTERSITICS OF CONSTRUCTION SYSTEMS

The construction system of the building is a complex of interconnected and interacting structural elements that interact with each other in relation to the surroundings. The most important function of the construction system is the load-bearing function. The construction system must also withstand the effects of the environment - static and dynamic loads, temperature, humidity, noise and other physical, chemical and biological effects. Each building is divided into floors and tracts.

The main components of the building include foundation structures, vertical load-bearing structures (walls and columns), horizontal load-bearing structures (ceilings, balconies, ledges), staircases, ramps and roof construction.

According to the static effect, the construction structures are divided into load-bearing structures and non-load-bearing structures:

• Load-bearing structures transmit any load acting on the object, e.g. bearing walls, pillars, roof structures, foundations.
• Non-load-bearing structures do not carry any load (except their own weight), they usually have a splitting or insulating function, such as internal partitions, peripheral insulating walls, doors and windows.

Cooperation of elements of the structural system must ensure system stability. Stability is the ability of a building to resist the external effects of the load without deformation (change of shape), deflection or total destruction.

The choice of the construction system depends on the parameters of the proposed building and it is based on the general requirements for the construction of the building structures. For the design of the construction system, the following parameters must be taken into account:

• Purpose, spatial and shape solution of the object
• Territorial and site conditions
• Dimensions and loads of ceilings
• Construction height of the floors
• Material base and technical possibilities
• Foundation conditions
• Environmental influences
• Fire safety
• Operational technical requirements
• Architectural requirements
• Energy performance of construction and operation
• Life expectancy
• Investment and operating costs, etc.

Design of the construction system should take place in dialogue and co-operation between the architect, designer and the technologist in order to achieve an optimal solution for taking into account all requirements. Due to the variety of requirements and their mutual harmonization, the proposed construction system is always a compromise solution.

BASIC CLASSSIFICATION OF CONSTRUCTION SYSTEMS

Construction systems can be divided into:

• Construction systems of multi-storey buildings: are characterized by vertical load-bearing structures carrying all the loads into the foundation soil. These supporting structures ensure the stability of the whole object. Construction systems of multi-storey buildings include wall systems, skeleton systems, their combination or core construction systems and superconstruction.
• The construction systems of hall buildings are characterized by their roofing and free interior layout

Floor (storey) is part of a building defined by two consecutive levels of the upper surface of the supporting part of the ceiling structures. At the lower floor, based on the raised terrain or embankment, the plane is defined by the upper level of the underlying floor structure.

The vertical distance between the upper surfaces of the support structure ceiling is referred to as structural floor height. The headroom is defined by the vertical distance between the floor surface and the lower level of the ceiling structure of the same floor

The tract is the space part of a building defined by two consecutive vertical planes passing through the geometric axes of vertical wall or column structures. The building can be single-tract or multi-tract. Depending on the position in the building, we recognize the tracts of the transverse tracts and the longitudinal tracts:

• Longitudinal tracts are parallel to the longitudinal axis of the building.
• Transverse tracts are perpendicular to the longitudinal axis of the building.

According to the arrangement of the vertical structures of the object relative to its longitudinal axis, the construction systems are divided:

• Longitudinal systems
• Transverse systems
• Two-way systems

According to the building technology used, the following construction systems are recognized:

• Brickwork systems (masonry) made of pieces building material connected to a mortar or other bonding layer.
• Monolithic systems made of ductile building materials deposited into a mold and solidifying directly in the structure.
• Prefabricated systems composed of pre-fabricated components which are interconnected in the joints.
• Combined systems

Keywords: Multi-storey building, wall construction system, longitudinal system, transverse system, column construction system, core structures, superconstruction

BASIC CLASSSIFICATION OF CONSTRUCTION SYSTEMS OF MULTI-STOREYS BUILDINGS

The construction system of multi-storey buildings is characterized by the predominance of vertical load-bearing structures, transferring all loads to the foundation soil.

According to the type of vertical load-bearing structures, the construction systems of multi-storey buildings are:

• Wall construction system
• Column construction system (skeleton construction system)
• Combined construction system
• Core structures
• Superconstruction

WALL CONSTRUCTION SYSTEM

The loading of ceiling structures and the effect of horizontal forces are transferred to the foundations by means of load-bearing walls. Wall systems are used in buildings with requirements for smaller indoor spaces (eg Accommodation facilities). The inner load-bearing walls must meet the static requirements. In addition to static functions, the outer load-bearing walls must also meet the thermal-technical parameters. Openings in the load-bearing walls must meet the requirements without compromising static feature walls. The wall construction systems are divided according to the layout of the supporting walls in the building:

Longitudinal construction system

The load-bearing walls are arranged parallel to the longitudinal axis to form longitudinal tracts. The ceiling structure is normally laid in a direction perpendicular to the longitudinal axis of the building.

Spatial rigidity in the longitudinal direction is provided by the longitudinal supporting walls themselves. The stiffness in the transverse direction is ensured by the ceiling structure, possibly by the transverse stiffening walls (eg gable wall, staircase wall, mezzanine wall, etc.). Objects with a longitudinal wall system are usually made of bricks or blocks.

Due to the static function of the load-bearing walls, the size of the window openings is considerably limited, the facade is a massive impression without architectural variability.

The advantage of the longitudinal construction system is the openness of disposition and variability. The disadvantage is the small architectural variability of the facade, the lower stiffness of the system and the resulting usability only for buildings with a small number of floors.

Transverse construction system

The load-bearing walls are perpendicular to the longitudinal axis of the building and form transverse tracts. The ceiling construction is realized in the longitudinal direction.

Space stiffness and stabilization are provided by the supporting walls themselves in the transverse direction. In the longitudinal direction, stiffness is ensured by additional walls and a longitudinally laid ceiling structure.

Internal load-bearing walls can be used to ensure that acoustic requirements are met between rooms (hotel rooms, apartments, etc.). The peripheral non-bearing walls are mainly function to protect the internal environment against climatic conditions (heat-insulating function).

The disadvantage of the transverse construction system is less variability and dispositional freedom. The advantage is better structural stability and suitability for objects with more floors.

Two-way construction system

In the case of a two-way (bi-directional) construction system, the supporting walls are arranged in the longitudinal and transverse directions. Ceiling structures can be stored in both directions.

The advantage is high room stiffness and stability. The bi-directional system is suitable for high-rise buildings. The disadvantage is the very limited layout and low variability of the interior space.

COLUMN CONSTRUCTION SYSTEM – SKELETON SYSTEM

Principle of the column system consists in separating the load-bearing function and the function of cladding. All loads carry vertical elements - columns. Non load bearing walls perform the function of separating and insulating (cladding, partitions). For columns, only heavy-duty materials such as steel, reinforced concrete or wood are used.

The advantage of column systems is the relaxation of the layout and the variable design of the building. The disadvantage is lower spatial rigidity compared to wall systems.

According to the method of transferring the load, the column system is divided:

• Frame skeleton system (beam and column system, post lintel system)
• Flat slab with column capital skeleton system
• Flat slab skeleton system

Frames skeleton system

The basic element of the frame skeleton is a frame made up of two columns and a beam. Ceiling loads are transmitted to the columns via frame bars. Frames can be single or multi-storey. According to the arrangement of frames in a building distinguished:

• Longitudinal frames:  The beams are parallel to the longitudinal axis of the building. Due to the low space stiffness, this system is mainly used for low-rise buildings. Bracing provides intermediate transverse walls (e.g. gable walls) or cross beams (girders). The disadvantage is the shading of the interior space and the limitation of the possibilities of façade rendering. An advantage is a free layout for longitudinal distribution.
• Transverse frames: The beams are perpendicular to the longitudinal axis of the building. Transverse frame frames are well-resistive to horizontal loads and are also usable for larger buildings. The transverse frames allow for a variable appearance of the facade and do not interfere with the interior of the building. The disadvantage is the more complicated management of longitudinal installations.
• Two-way frames: The beams are positioned in the transverse and longitudinal directions. Two-way (bidirectional) frames are characterized by high stiffness and are suitable for high-rise buildings or for buildings in underdressed or seismically unstable areas.

Flat slab with column head skeleton system

Flat slab with column head skeleton system carry the load on the columns through the expanded column heads (capital). The column capital protects the ceiling slab from piercing and shortens its effective span.

Flat slab with column head skeleton are very affordable and are suitable for objects with a large load of ceiling structures, especially for manufacturing and storage facilities. The disadvantages of skeleton with column head are the visible column head and the more difficult to guide the vertical installation.

Flat slab skeleton system

Flat slab skeleton system has a ceiling structure supported directly by columns. In thin slabs real danger puncture plate column. There is a real danger of piercing the slab by column. The piercing of the column can be prevented by increasing the reinforcement above the supports. Flat slab and column joining can be done either with a hidden column head or a hidden beam.

Flat slab skeleton system has low spatial stiffness and must be complemented by wall or core fasteners. These skeletons are used in buildings with a small load of ceilings, especially for civil buildings and residential buildings.

The advantages of the flat slab skeleton are the flat ceiling and the possibility of bi-directional installation guidance.

COMBINED CONSTRUCTION SYSTEMS

Combined construction systems are based on the advantages of individual construction systems. The combination of load-bearing walls and columns creates diverse spatial formations with high stiffness and minimum weight. The column construction allows for free variability and layout options. Columns carry the load from the ceiling structure and the walls fill the stiffening functions and provide spatial stiffness and stability.

Combined construction systems can be implemented in a number of variations:

• Combination of longitudinal wall system with inner column system
• Combination of transverse wall system with inner column system
• Combination of transverse and longitudinal walls with inner column system
• Combination of two-way (bidirectional) column system with inner core

CORE CONSTRUCTION SYSTEM

The core construction system transfers the load to the building foundation with a central stiff core. All functions and operations that do not require lighting and direct ventilation are designed to the core (lifts, staircases, installation shafts, etc.).

The construction of individual floors of core systems can be carried:

• Primary lower horizontal supporting structure cantilevered overhang from the parterre core which carries the secondary uprights upper floors.
• Primary upper support structure disposed in the core head, on which the ceilings of the lower floors are suspended.
• Ceilings individually executed from the core into which all loads are transmitted directly.

Core systems are used mainly for the construction of high-rise buildings with a square or circular ground plan. Their advantage is the release of the ground floor and easier ways of setting up. The possibility of significant architectural design attracts architects, even though it is statically and structurally complicated solution.

SUPERCONSTRUCTION

Superconstruction are two-stage building constructions that arise by concentrating loads into a limited number of massive elements of the main (primary) supporting structure into which a secondary (secondary) structure is inserted. The superconstruction is especially used for extremely tall buildings over 50 floors. The primary structure is proposed with a long life, thus allowing the possible change of the secondary structure.

The primary load-bearing structure is typically formed of a super-frame by which each floor having a height corresponding to the height of several storeys inserted. The secondary structure is then inserted into the super-frame space, and the secondary structure is made up of subtler elements. The secondary structure can be mounted or suspended on the superconstruction. There can be a free open hall space between the suspended and stored floors.

Keywords: Hall, slab (plate), truss, vault, shell, folded slab, pneumatic construction

CONSTRUCTION SYSTEMS OF HALL BUILDINGS

Hall buildings allow the creation of free spaces with little or no internal support. The characteristic feature of hall buildings is a large ground plan and a relatively small height. Hall objects are used especially for single-storey buildings. Unlike the construction systems of multi-storey buildings, the hall buildings are characterized by a supporting roof structure.

The hall object can also include internal built-in floors with different height requirements:

• Two-storey halls
• Large-scale halls
• Combined monoblocks

The hall buildings are characterized by extremely high variability. The repeatability of the types of indoor buildings is significantly lower compared to multi-storey buildings, they are far more individual objects.

Hall objects are used especially for:

• Cultural purposes (theatres, cinemas, exhibition pavilions, gathering, etc.)
• Sports purposes (multipurpose and sports halls, tribunes and stadiums roofing, swimming pools, etc.)
• Manufacturing and storage purposes (production halls, warehouses, markets, etc.)
• Traffic purposes (station halls, platforms roofing, car and bus garages, service halls and repair shops, docks, etc.)

In most cases, hall objects have a split supporting function and cladding. The load-bearing function transfers static and dynamic loads to the foundation structures. Cladding provides the desired state of the internal environment and consists of roof cladding, curtain wall and substructure.

The design must be solved, depending on their spatial stiffness, in order to capture the horizontal forces in the pushed and drawn systems, to allow for greater deformability of the structure (especially for drawn systems). The interaction of the subsystem and the assembly (packing) structures and the overall stabilization of the roof sheets in the tensile systems is of considerable importance.

From the viewpoint of static stress, hall structures can be divided:

• Bending construction systems
• Compressive construction systems
• Tensile construction systems

BENDING CONSTRUCTION SYSTEMS

The basic element is a bend-loaded, simply inserted or interlocking element that transmits primarily vertical loads. All load on the simply stored element is transmitted by bending stress in the middle of the span. The load capacity then depends on the cross sectional modulus of the beam and the permissible stress of the material. If the beam structure is cantilevered into the support (the structure is rigid), a bending moment is created in the support area, which is also transmitted by the supporting (vertical) structure of the frame system. As a result of the interaction of the supporting structure, the bending moments in the frame are reduced. Since the upper beam of the beam and the frame beam are stressed, stability must be ensured before turning. Structural systems stressed mainly on bending include plate systems, trusses and frame systems.

Plate system

Plate systems, as it is already apparent from the title, are made up of different types of boards (with reinforced ribs, cellars, etc.). They are designed to stretch to 24 meters and element widths up to 3 meters. To ensure stiffness, the boards are interlocked.

A plate structure could be formed of unidirectionally or bidirectionally tensioned structures carrying bending loads in both directions. The system consists of plates from planar or spatial lattice trusses.

Trusses system

Truss system consists mainly of the roof trusses (beam elements) deposited on the columns, beams or walls. Trusses can have different shapes (straight head, rack, saddle, arc etc.), various structural solutions (solid panel, lattice etc.) and various material design (reinforced concrete, steel, wood etc.). The roof trusses are stored within the roof surface elements (ribbed or cassette panels with lightweight slab) or roof purlins carrying the roof cladding.

Frame system

The frame system transfers the frame bending moment to the frame stand as a result of the rigid connection. A disadvantage of bending stress of machinery frame can be partly eliminated by a continuous frame structure design. The course of the bending stress in the structure depends on the bending stiffness of the stand and the riser, and the ramps are also affected. The higher bending moment is then concentrated in places with higher bending stiffness. The frame structure may be in the form of a cantilevered frame, two-hinge or three-hinge frame or cantilever frame. The construction can be solved from concrete (reinforced concrete structures, monolithic or prefabricated), steel (thin-walled or full-body profiles) or wood (solid or lattice, etc.).

COMPRESSIVE CONSTRUCTION SYSTEMS

If the arc shape or flat structure designed in the shape of the load pressure line (resultant line or area), the structure transmits pressure loads. Since the shape of the structure is stable but the load is not necessary, part of the load is transmitted by the bending moment. The design should be designed to convey the prevailing load by its own weight and snow. This creates a parabolic shape of the compressive structure. The static effect of the compressive structure can be achieved by shaping the frame construction so that the frame bending capacity is zero. The support system then transmits the vertical and horizontal responses of the arched (compressive) structure. Compressive construction systems include arc structural system, flat compressive construction system (vaults and shell), rod structural system and folded slab structure system.

Arc structural systems

Arch structural systems have a support system designed for buckling pressure in combination with a bend. The stiffness of the sectional structure prevents buckling in the plane of the arc. Stiffness of the ceiling boards and own flexural rigidity prevents deviation from the plane of the arc. Arcs can be clamped, two-or three-jointed articulated. Most often steel or reinforced concrete is used as a material. The construction itself can be lattice or full-body. Spans these structures may reach 100 m.

Flat compressive construction systems - vaults

The vaults are loaded with buckling pressure and bending. The stresses are transmitted by overvoltage of the cross section due to the prevailing vertical load. The construction result is a massive vault construction and limited ability to transfer point loads. For correct design, it is important to know the shape of the result line from the load by the weight of the structure. The material is used mainly stone or brick. For the proper functioning of the vault, the shape of the resultant line is significant from the load by the weight of the structure itself. The pressure lines must always remain inside the cross section core (in the case of the rectangle in the inner third of the height).

Flat compressive construction systems - shell

The shells have a small structural thickness and the bending loads are transmitted only to a limited extent. The stability of the compressive parts is ensured by using the shape of a double curvature construction or by co-operating with reinforcing ribs and shell faces.

Rod structural system

Rod structural systems have to a certain extent similar effects as a flat construction of the same shape. The principle of a slab or rod structure is an effort to replace the static effect of a flat structure with bars made of reinforced concrete, steel or wood. The cylindrical vault-shaped rod structure acts as a cylindrical shell clamped into rigid front walls.

Folded slab structure system

Folded slab structure is formed from flat triangular elements creating a rigid spatial system. Suitably selecting the shape of folded slab can be achieved by translational or rotational surfaces.

TENSILE CONSTRUCTION SYSTEM

The tensile construction system includes suspension systems, pneumatic systems and suspended systems.

Suspension systems

The suspension systems may be truss, panel, cable and membrane structures. The elements do not have bending stiffness and are arranged in parallel or radially in a single layer or multilayer arrangement. Load transfer occurs through the normal force in the profile and the horizontal component of the supported reaction. This component lifts the support system high above the terrain. This requires its efficient construction design.

Pneumatic systems

Pneumatic systems are carried by overpressure of the internal air. The construction consists of a thin membrane preloaded with internal overpressure. In the case of low-pressure structures, the overpressure in the entire space is 100-300 Pa and is stabilized by large spans in combination with surface stiffening ropes. For high-pressure structures, the air pressure is 0.1-0.5 MPa and is concentrated in the so-called skeleton of the object (ribs, curves). Less sponge up to 25 m are used.

Suspended systems

The principle of the suspended system is the suspension of the roof beam by means of bars anchored to pressed pilots, arcs or frames, etc. It is a multistage system reminiscent of the so-called superstructures in multi-storey buildings. It is a multistage system reminiscent of the so-called supersconstruction in multi-storey buildings. It therefore belongs to efficient roofing systems for large spans (150 m or more).

Keywords: Construction joints, dilatation, expansion joint, expansion unit, volume changes, uneven settling, rheological changes

The construction joint is defined as the distance between the two building blocks. This type of joint does not have the volume or shape changes - the gap is constant.

The expansion joint is a joint that divides buildings or their individual parts into smaller rigid units. Dilatation is performed to prevent transmission of non-force effects from one part of the structure to another so as not to interfere with the required functions.

The expansion joint is carried out in areas predicted extreme loads, loss of stiffness of the structure, structural changes, changes in the construction system and layout, in places of change of height of a structure or object, in places of geological breaks and irregularities.

Unforced effects include:

• Volume changes due to temperature
• Volume changes due to moisture
• Rheological effects (creep and shrinkage)
• Changing the shape of the foundation joint (bottom surface)

Unforced effects cause mechanical stresses in structures that often exceed the stresses due to common force effects (self-weight, wind load, etc.).

Splitting the structure of a building into individual components, which tend to vary in shape and different subsidence, is appropriate for reducing and reducing stress. Expansion units can be defined as smaller parts of the structure separated from the whole by expansion joints.

Expansion joints eliminate:

• Static effects - volume changes, uneven settling
• Dynamic effects - shocks
• Acoustic effects - noise transmission of structures and vibrations
• Heat-technical effects - Heat and moisture transfer of structures

Each material changes its dimensions with a change in temperature and humidity.

Volume changes can be caused by:

• Changing the temperature of the external and internal environment (thermal expansion of materials) - each material
• Changing the moisture of the materials (drying and swelling)
• Rheological changes of the materials
  • Shrinkage - Volumetric changes due to drying of water from the structure of solidifying and hardening concrete, shrinkage depends on the composition of the concrete mixture, its processing, dimensions and reinforcement of the elements.
  • Creep - volumetric changes due to the load size and the time depends on the composition of the concrete mixture, its processing, and the dimensions of the reinforcement element, load size, load type (permanent, accidental, dynamic) and the time of the load.
• As a result of chemical processes in materials (eg corrosion)

• Element breakage by tensile cracks
• Compression element failure
• Expanding effect on surrounding structures
• Creation and expansion of joints between element and surrounding structures
• Rheological changes of materials

Maximum distance of expansion joints in masonry with lime mortar:

• burnt bricks                          100 m
• sand-lime bricks                  50 m
• concrete blocks                   50 m
• natural stone                        60 m
• reinforced concrete             40 m

For plain or weakly reinforced concrete, the maximum lengths of monolithic expansion units for the protected structure are 30 meters and for the unprotected structure 24 meters. The maximum size of the dilatation units of the steel structure is determined by static calculation.

Construction design of the expansion joints:

• Duplication of supporting structures
• Unilateral sliding fit
• Cantilevered ceiling structure
• Inserted field with slide bearing

• Irregularities in the substructure of the object - irregular and oblique loading of soil layers with different compressibility, different levels of groundwater level, undermined area, additional changes in the subsoil or level of ground water level
• Different loads in the footing bottom - different height of the part of the building, different utility loads in different parts of the building, inappropriate design of the area of individual flat foundations
• Different foundation structures of parts of the building - the combination of shallow and deep foundations
• The time interval between the realizations of the different units of the building - the new part follows the older one, where the settlement has already taken place.

• Expansion joints must allow vertical displacements
• Expansion joints pass through the whole object, including the foundations
• Foundations must not interfere with one another
• Must comply with the required thickness joints

• Sided cantilevered horizontal structures
• Reversible cantilevered horizontal structures
• Fields inserted
• Modulation adjustment

Keywords: Foundations, subsoil (foundation soil), earthworks, deep of foundations, excavations, shoring, underground walls

The foundation engineering is engaged in designing and establishing the foundations manner. The foundations are load-bearing components of objects that provide the load carrying structure into the subsoil. The foundations must be designed to safely transmit all loads with minimal distortion and without breaking the subsoil. According to the way the load is transferred, are distinguished shallow foundations and deep foundations.

Subsoil is a functional part of the building. The footing bottom is an area where the foundations meet the subsoil.

Soil is unpaved or slightly hardened rock

Rock is a heterogeneous mixture of various minerals, sometimes organic compounds, volcanic glass or a combination of these components.

Topsoil is the upper thin layer (100-300 mm) on the surface with plant and animal residues. Topsoil is rake off before work and later is thrown back around the building.
Mud is clay soil mixed with a considerable amount of silica sand, mica, calcium, iron and organic matter. If it contains more than 40% sand, it is referred to as skinny mud. At a sand content below 40%, it is a greasy mud. Holding greasy mud in hand, it sticks and holds together, while the skinny mud does not stick and decay. These include brick clay, fireproof mud and kaolin

Clays are siliceous sediments, consisting of 25-30% clayey earth and 65-70% more silicon dioxide. They are always very fine, without sand or mixed with fine sand, very colloidal and water impermeable. The water gets on the volume, shrinking by drying. A special kind of clay is bentonite, which is very fine, so it has properties of colloidal substances. It receives plenty of water - up to seven times its own weight.

Marl or marlstone is clay-mud containing 25-60% calcium carbonate and magnesium carbonate. Marlstone soil have tended to sliding. There are very dangerous.

Fusible mud containing a mixture of alumina or lime clay, sand and mica. Contains 10-40% lime. Water-tight. It is slightly softer than clay, and in nature it has a slate structure. This group also includes shale or claystone, often containing coal.

Loess is a fine, sandy, dusty wind. It consists of a higher content of calcium compounds and up to 50% of dust, mostly silica. It has less ductility than clay and marl.  Loess is yellow to light brown, so is often confused with mud. If we put it between our fingers, it is finer than clay, since it contains grains of sand less than 0.1 mm. It draws water and its water permeability is very considerable because it is penetrated by the hair channels. The unpleasant nature of the loess is its great tenderness: up to 5-6 m above the ground water level. However, if it is dried up thoroughly and properly, it is relatively small for the water.

There are 3 classes according to soil exploitation:

• Class I is defined by mining by conventional excavation mechanisms (bulldozers, excavators) or by hand.
• Class II is defined by mining with special mechanisms - rippers, rock spoon, hammers
• Class III is defined by mining by blasting works

Depth of foundation affects the size of the building's settlement. Greater depth reduces the overall settlement construction. The depth of foundation is the difference between the level of the footing bottom and the closest terrain point. The depth of foundation is determined with respect to stability and settlement construction, climatic conditions (freezing, drying out of the soil) and geological and hydrogeological soil profile.

The minimum depth of the foundation is determined by climatic conditions - winter temperature and the type of soil. In the case of freezing of footing bottom under the foundations, there is a real risk of increasing the volume of soil under the foundations (water changes in the state of ice to increase its volume) and thus the formation of stresses and consequently faults. Depending on the soil, we choose the depth of foundation:

• 500 mm for rock and weak rocks soil and under the interior walls
• 800 mm from landscaped terrain (loose soil outside the mountain range)
• 1000 mm from landscaped terrain (cohesive soils outside mountain areas)
• 1200 mm in cohesive soils with ground water depth less than 2 m deep

Depth of foundation in mountain conditions always depends on local climatic conditions. The type of soil is always determined on the basis of the site survey results. In the case of inappropriate soil types, the soil can be improved by replacing with other soil (cushions), compaction, drainage, soil admixtures (grout, lime + polit) or by drying.

On cohesive soils, due to the load, the water is exuded from the pores and thus partially bursts and consequently decreases the foundations. That is why rough sand, gravel or gravel is used as drainage under the foundation. The height of the embankment must secure the isobar under the foundations so that the stress is less than the bearing capacity of the foundation soil.

Earthworks in civil engineering are divided into preparatory earthworks, major earthworks and finishing earthworks.

The main types of earthworks are clearances, embankment and backfills. Theclearances eliminate terrain inequalities. It also includes rake off the topsoil. The topsoil is surface organic soil with a thickness of 150 to 300 mm. The embankments are poured structures built on the surface of the territory. The embankments are formed over thin layers (150 - 700 mm) which are compacted. The backfills are sprinkled structures that fill the space below the terrain level and around the building structure. The bulk material is non-frost-free, stable and low compressible materials (eg gravel). The backfills need to be compacted. The most important earthworks are excavations.

Excavations are carried out by excavating below ground level. The area in which excavations are made is called the excavation site. Exhausted soil is called a borrow material.

According to the shape and dimensions of the excavation, there is a pit, trench and shaft. The pit is an excavation whose length and width is greater than 2 meters. The furrow has a predominant length dimension and a maximum width of 2 meters. The shaft has a predominant depth dimension and a maximum floor area of 36 square meters.

The lifting of the soil is carried out by various types of earthmoving machines. Hand excavations are limited to clearing work. The method of excavation is chosen according to the volume and type of rock.

The footing bottom must not be broken during excavations. It must also be protected from climatic effects (rain, flooding, drying and freezing). The soil layer (approx. 200 - 500 mm) is retained at the bottom of the excavation as a protection layer, which is removed just before the realization of the foundations.

Excavation walls must be secured against landslides. The choice of method depends on the excavation depth, physical-mechanical properties of the soil, the loading of the edges of excavations and the time the excavation remains open.

Vertical walls can be excavated in cohesive soils with a depth of no more than 1.5 meters. In other cases, excavation walls must be provided with one of the following options:

• Sloping walls of excavations: The slope of the excavation walls should be as steep as possible because the cubes of earthworks and the excavation area are increasing. At the same time, minimal slope, defined primarily by the angle of internal soil friction and the coefficient of soil cohesion, should be respected ((eg sandy gravel 1:1, clayey sand 1:0.50, dust 1:0.25). In excavations deeper than 3 meters, slopes are interrupted by field benches with a minimum width of 500 mm.
• Shoring of excavation walls: Shoring is a temporary building structure that protects sloping walls against landslide during excavation work. Timbering must be done directly with the excavations. Timbering consists of sheeting and bracing. Sheeting is flat part of shoring which is in direct contact with the soil. Sheeting consists of wood or steel planks laid vertically, horizontally or obliquely. Soil pressure acting on sheeting is intercepted by horizontal and diagonal struts. Depending on the construction and the method of implementation, we distinguish:
  • Shoring with attached sheeting: Attached sheeting is used in cohesive and incoherent soils. According to the coherence of the soil, the struts are laid either at a meeting or with spaces, horizontally or vertically
  • Piles shoring: Piles shoring consists of a piles rammed into the subsoil. Horizontal sheeting is triggered between pilots. Bracing pilot induces high strength sheeting. This method can be used in wide construction pit and up to 20 m depth. Piles shoring cannot be established in boulder soils where the defects cannot be pulled to the required depth or at the necessary distances.
  • Weft shoring: Weft shoring is used in construction pit and grooves. It may be vertical or oblique.
  • Driven shoring: Driven shoring is carried out in cohesive, cohesive and incoherent soils where we can get secure enclosed space in which we can work. It is the costly and hardest way of shoring.
  • Triggered shoring: Triggered shoring is used in less cohesive soil at excavation depth of up to 6 m. Carved frame from round logs, columns, vertical shoulder and wedge.
• Underground walls: Underground walls are used to secure the walls of deep excavations, in blank space or at a great load on the edges of excavations. Depending on the building material used, we distinguish the underground walls of clay, clay-cement and concrete. Underground walls can fulfil not only the function of armor and sealing, but also the function of construction and foundation for the peripheral load-bearing masonry. Milano's underground walls are made up of a continuous groove with a depth of up to 40 meters, into which prefabricated concrete panels are launched or they are concreted in a width of 0.6 - 1.0 m and at the same time serves as the load-bearing wall of the underground part of the building.
• Pile walls: Pile walls can be used in soils and rocks with low strength. The individual piles overlap each other below the groundwater level. Piles simply touching above the water level and the axial distance is less than 2 m. Non-anchored piles are used up to 6 m if the span is larger, they are anchored or bracing.
• Sheet pile walls: Sheet pile walls are used in cohesive to solid and non-cohesive soils (outside the boulders). They can be used below the level of ground water. The locks are connected to each other to ensure water tightness. The best known type is Larssen sheet piling which can be used up to a depth of 20 m. After finishing the work, it is possible pull out and re-use them.

Pad footing are the foundation structures that are mostly made for the foundation of the column construction system. Pad footings transmit point loads from the columns into the ground. The ground plan of pad footings is mostly square, less often rectangular or circular. Square pad footings are designed especially for the centre load. The pad footings are economically and productively advantageous if their side is not more than half the axle spacing of the columns, otherwise grid, slab or pile foundations are more useful.

Vertical constructions such as partition walls, perimeter structures, or staircase walls are based on foundation lintels or foundation thresholds that carry the load on individual pad footings.

The shape, material and dimensional design of the pad footings depends on the anchorages of the columns or other structures mounted on the feet. pad footings can be one-stage or two-step.

Classification of pad footings according to the technology implementation:

• Monolithic pad footings
  • Pad footings made of plain concrete
  • Pad footings made of reinforced concrete
  • Pad footings interspersed with stones
• Prefabricated pad footings
  • Hollow (calyx) pad footings
  • Full pad footings

Monolithic pads are made of plain concrete or reinforced concrete, optionally as combined:

• Pads made of plain concrete are used only for small layout plan dimensions (up to 2 m of side size), for centrifugal loads and for bottom footing with permissible load capacities above 2 MPa. Surface of the pad is defined by the load and permissible bearing capacity of the foundation soil. The height of the monolithic pad is determined by the size of the lining and the displacement angle. If the pad height is greater than 1 meter, the pads are designed to be stepped. The concrete foot can be concreted directly into the formwork. Pads made of plain concrete can be concreted directly into the formwork.
• Pads made of reinforced concrete are designed for larger layout plan dimensions, eccentric loads and base soil with accessible stresses up to 0.15 MPa. Reinforced concrete pads are relatively low because the displacement angle tgα is 0.5 - 1. The top surface of the pads is most often skewed. If the angle of inclination of the upper surface is less than 35 °, the top of the pads can be concreted without formwork. At a higher slope, formwork is required. The pads are concreted into ready formwork, for which the excavation on each side needs to be extended by the necessary handling space. Below the reinforced concrete pads, it is necessary to make a concrete foundation layer with a thickness of 50 to 100 mm to protect the reinforcement against corrosion.

Pre-cast pad footings made of reinforced concrete or pre-stressed concrete are used for assembled skeleton structures. Prefabricated pad footings may have different ground planes (rectangular, circular, polygonal, star-shaped, etc.). The most widespread are the pads with rectangular cross sections. These pads are manufactured in two basic design variants:

• Hollow (calyx) pads footings or nesting pads have a recess into which a prefabricated column is mounted on a cement mortar bed, and after locking they are concreted.
• Full pads footings are manufactured as one-stage or multi-stage. Column connection with pad provides reinforcement anchor inserted into the opening in the pads and potting cement mortar. The reinforcement is welded to the shod foot of column.

Pre-cast pad footings are laid on the base panels or on monolithic load distribution slab. The dimensions are determined by calculating the column load and bearing capacity of the foundation soil. The bottom footing must be aligned with a layer of sand or base concrete at a thickness of 100 and 150 mm. The foundation lintels can be supported by the pad footings.

Lightweight continuous structures (walls of non-cellar light buildings, perimeter walls, etc.) can be based on a foundation lintel which load is transferred to the foundation block to the bottom footing in frost-free depth.

Strip footings are used to support both load-bearing and non-load-bearing walls from 6 N/m² - i.e. approximately 150 mm thick and 3 m high. Lightweight partitions and structures are placed directly on reinforced concrete. The minimum size of the strip footing is 300 x 300 mm. Columns are based on strip footings in cases where the pads are too large or in the case of the skeletons with unevenly laid ceilings.

Strip footing forms a continuous beam, which may be rectangular, stepped, plate or ribbed in cross-section. Depending on the material used, we can distinguish strip footings made of quarry stone, plane concrete and reinforced concrete.  Concrete and reinforced concrete structures may be monolithic or prefabricated.

The width of the strip footing (b) is determined by the load and admissible bearing capacity of the subsoil. The height of the base (h) is derived from the size of the foundation extension (a) and the size of the displacement angle and the permissible load of the suboil. For the calculation of the height of the strip footing, the relation can be used: h = a.tgα, where tgα is for the stone 2 - 3, for plain concrete 1,5 - 2 and for reinforced concrete 0,5 - 1.

Strip footings made of quarry stone are used only rarely. The most commonly used stone is marlite. Strip footings can be used for low-load walls. Strip footings can be made one or two steps.

Strip footings made of plain concrete are used for wall constructions. They can be single-stage (rectangular cross section) or graded at higher base heights. The plain concrete strips have a minimum size of 300 x 300 mm

Strip footings made of reinforced concrete are used for heavy loads transmitted to the foundations with less bearing and non-homogeneous subsoil. The shape of the reinforced concrete strips may be rectangular, with a sloping upper surface or a cross-section of the inverted T. Strip footings made of reinforced concrete are concreted either in longitudinal or transverse alignment with the supporting beams of the skeleton. The stiffness of the strips for large buildings can be increased by stiffening strip footings located perpendicular to the main strip footings. Below the reinforced concrete strip footings, it is necessary to make a base layer.

Strip footings assembled buildings can be made of prefabricated panels. Prefabricated strip footings are used when loading the foundation soil is from 0.2 MPa to 0.35 MPa. The prefabricated parts are made of concrete or reinforced concrete with dimensions graduated for different loads and up to 3 meters. The parts have a rectangular or trapezoidal cross-section. The pre-cast strip footings are put into a sand bed of 100-150 mm thickness, which equalizes the bottom of the excavation.

Grid fottings re formed by strip footings, generally perpendicular to each other. Footing grid are used for heavily loaded skeletal structures designed in non-homogeneous subsoil in soils with high compressibility, undermining or seismically unstable areas.

The foundation slabs distribute the load on the entire surface of the ground plan of the building so that the bottom footing is stressed more evenly than other types of foundations. Foundation slabs are used in inhomogeneous, low-load-bearing and extensively compressible base soil. The slabs are designed if the calculated width of the strip footing is so large that there is little soil between the concurrent strips. The slabs are used for the construction of high-rise buildings and for extremely heavy-load structures. The foundation slabs can also be used for groundwater foundation.

It is always necessary to consider the use of the foundation slab, since it is rather expensive and demanding for mass consumption and, especially in the case of insufficient reinforcement, is subject to failure due to the uneven settlement of the building.

The foundation slabs are made of reinforced concrete as straight, ribbed, grate, headed, shell or gable. Straight slabs have a constant height of 400 and 1200 m across the floor plan and are used at distances of supporting walls or columns up to 4 m. With the greater axial spacing of vertical structures or greater load on the slabs, it is preferable to reinforce the slabs with ribs that are better resistant to deformations. The rib can be placed above or below the slab. The advantage of a top ribbed slab is that it allows positioning between the ribs. The disadvantage is the need to create a formwork ribs and separate floor construction. The slabs with the lower ribs are not suitable for foundation below the water due to the complicated implementation excavation and waterproofing. Heavily loaded skeletal structures can be based on head or grate foundation slabs. The head slab is very advantageous both in terms of production and economy and is also the most commonly used. The only disadvantage is the protruding feet above the floor level. Instead of a slab, a monastery vault or slab reinforced with a beam system can be designed, which is more rigid than a simple slab.
 

Keywords: Deep foundations, foundation piles, prefabricated piles, monolithic piles, micropiles, foundation wells, caissons

Deep or vertical foundations transmit the load to the depth through vertical elements. Deep bases are proposed in the case of insufficient bearing capacity and high compressibility of the surface layers. Ground structures are mostly based on pilots. Less often on shaft pillars, foundations wells or caissons.

Foundation piles are rod elements of the circular or square section, which transfer the load of the building on the foundation soil in depth. Piles are elements whose length to transverse dimension is at least 5: 1.

Depending on the transmit the load to the subsoil, the piles are pushed, tensile, oblique, and piled loaded by bending and buckling. Most often there are pushed pilots (end bear, friction and bearing-cum-friction pile). End-bearing piles carry the load predominantly by a tip that is supported by a bearing suboil. Bearing-cum-friction pile carry the load on both the tip and the friction on the casing. Friction piles do not interfere with load-bearing soil and are all their length in the non-loading-bearing soil to which they carry the load only by friction on the casing.

Depending on the material piles are distinguished by wood, concrete, reinforced concrete, prestressed concrete and steel.

According to the relationship, we distinguish the solitary pilots and group pilots. Solitary pilots do not affect each other. The contours of the loaded areas are not intersected at their peak and their axial distance is at least 6 x the diameter of the pile. Group piles are made up of several piles arranged below the shallow foundation structure. Group piles are affected and are always considered as one.

According to the manufacturing process, we distinguish pilots prefabricated (driven) and monolithic piles (excavated).

Prefabricated driven piles can be wooden, reinforced concrete, prestressed concrete and metal. They are made as full or hollow. They are driven by ramming, flushing, pushing, vibrating or other methods. The most widespread method is ramming. The pilot's heads must be protected from damage by a protective shard. Flushing is based on the flooding of the soil under the pile tip. The pile penetrates into the ground with his own weight, or with a slight ramming, to the into the flooded ground. Pushing the pile is done by hydraulic presses. The vibration driven is mainly used for steel pilots.

Wooden piles are used in places permanently below the groundwater level. Parts of water must be impregnated. The most commonly used square or circular diameters of 200 to 400 mm in length are up to 10 meters. The tip of the wooden pilot is provided with a steel shoe; the head is protected by the shards. The advantage of wood pilots is long life underground water and easy adjustment of length (shortening).
 

Reinforced concrete piles and prestressed concrete piles are used to a depth of 20 meters, exceptionally up to a depth of 50 meters. The piles are produced with a hollow cross-section or full. Full pilots usually have a circular, polygonal or square cross-section with bevelled edges. Piles with cross sections of 250 x 250 to 600 x 600 mm are strongly reinforced with longitudinal reinforcement with stirrups or spiral-shaped reinforcement. The tip of the pile should be protected with the steel tip. Hollow pilots are not load-bearing capacity and are replaced by the pipe with steel piles.

Steel piles are made of molded steel profiles or steel pipes. Their advantage is high strength, easy adjustment and reduction, and especially easy pushed into the soil, steel piles are used up to 60 meters deep.

Monolithic piles are manufactured on-site into pre-drilled wells as either sheeted or non-sheeted (with or without a casing pipe). Monolithic pilots may have a fixed cross-section along their entire length or are expanded. Monolithic piles are made of concrete or reinforced concrete. Concrete piles are used in the case of stress only. Reinforced concrete piles are used for stress and tension and bending. We distinguish between three basic types of monolithic piles – non-sheeted piles, piles with a casing pipe withdrawn and piles with a casing pipe left.

Non-sheeted piles can only be carried out in cohesive soils and above the groundwater level. Digging is usually done by drilling with a diameter of 600 to 800 mm. The concrete mixture is stored directly into the borehole. The piles must be concreted immediately after the excavation. If necessary, the borehole walls can be strengthened with clay lather.

Piles with a casing pipe withdrawn are used in all soil types and below groundwater. The casing pipe is a steel tube which drives into the soil by ramming, bruising or vibrating. The casing pipe may be open or closed at the bottom.

Piles with a casing pipe left are used in an aggressive environment where it is necessary to protect concrete against harmful effects. Kept steel casing pipe reduce the value of surface friction. These piles cannot be used as friction piles. When using open casing pipe, the soil remains inside the casing pipe and is subsequently extracted, for example by drilling. Concreting is carried out in the prepared borehole. These pilots are referred to as pre-drilled piles. Closed casing pipe is fitted with a plug in the heel which prevents the soil from penetrating in. The closed casing pipe are used in the so-called pre-driven piles. Once the required depth has been reached, the plug will come out. The concreting is carried out under the protection of the casing pipe for its gradual pulling out. Piles with a casing pipe withdrawn have a rough surface and can be used as friction pilots.

Micropiles or root piles are short piles of small diameter (80 to 250 mm) which are reinforced with reinforced concrete or steel pipe. Micropiles are made using a variety of technologies. Pre-drilled holes can be filled with cement grout and a perforated pipe is inserted into the drill. After the bore is sealed, this mixture is injected. It penetrates under pressure into the lower part of the borehole and into the boundary in the soil to form an expanded root. The fifth micropile achieves high strength. Micropiles are used for reconstructions and for the capture of buildings. Micropiles may be vertical or oblique.

Large-dimensional piles are prismatic or cylindrical deep foundations with a diameter of more than 0.6 meters. In the case of a diameter of more than 1.2 m are referred to shaft pillar. Large-diameter piles are used as a single pile and replace the whole group of pilots. Large-diameter piles are made of reinforced concrete, possibly coupled with a steel pipe.

The shaft pillars are either dredged or drilled. They are used up to a depth of up to 4 m, to which the piloting is not economical and at a depth of more than 4 meters in case of higher load carrying. In larger buildings, only pillars are drilled. Dredged shaft pillars are suitable for dry or soils with little leakage of water.

The foundation wells are underground structures of cylindrical or prismatic shape with a minimum diameter of 1 meter. The foundation wells are mainly used for the foundation in water-borne and easily disconnectable soils that allow the wells to be quick submerged.

The lifting of the soil is carried out under the protection of the shell consisting of hollow prefabricated elements, usually from the rings provided at the bottom with the cutting edge. The soil is extracted from the interior of the foundation well, and the substructures are gradually undermined and their own weight enters the subsoil. The inner space is concreted after reaching load-bearing soil.

The caissons are used for building foundations in the water. The caissons are large-area wells enclosed by a ceiling structure that creates a working chamber secured against water ingress and allows construction work under water.

To dispose of water from a caisson, it is necessary to achieve a pressure equal to the pressure from the outside of the caisson. Afterwards, workers can enter the caisson, where the earth extracts, and so the caisson submerges. After lowering to the desired depth inside the caisson be cast. Caisson forms deep foundations overlying structure.

Keywords: Masonry structures, brick masonry, stone masonry, block masonry, mixed masonry, brick bond, mortar

The basic function of vertical load-bearing structures is to transfer all loads from horizontal structures to the foundations of the object and stiffened the object. Other features may be dividing, thermal, acoustic, fireproof or aesthetic. According to the ground plan position, the vertical structure includes inner load-bearing walls, stairwells walls, peripheral walls, reinforcing walls, columns, pillars and partitions.

The masonry structures are made of individual natural or artificial masonry elements connected by mortar or laid dry.  The design of brick walls is based on static calculation, thermal-technical assessment and fire resistance assessment.

Bricks are manufactured in various materials and dimensional formats with holes or without holes. The most commonly used were burnt bricks of and metric perforated bricks.

• Lime mortars with a compressive strength of max. 1.0 MPa
• Limestone cement mortars with a compressive strength of 1.0 - 2.5 MPa
• Cement mortars with a compressive strength of 5.0 - 20.0 MPa

The final load-bearing capacity of the masonry does not only the properties of the used materials but also their mutual arrangement or bond. The classic brick bond is characterized by:

• A masonry pieces that are placed in horizontal layers
• Head joints should be shifted in two layers above each other
• Bed joints and head joins should be completely filled with mortar

According to the orientation of the bricks in the masonry, there are stretcher and header. The stretcher is a longitudinally oriented element applied in the face of the masonry by its length. The header is a transversely oriented element applied in the face of the masonry by its width.

Block masonry have evolved from brick masonry in response to stricter thermal technical requirements. The block masonry wall is implemented as brickwork. Thermally stricter requirements satisfy the blocks, which are lightened from the cavities or are lightened in mass. Blocks are made from lightweight concrete, diatomaceous earth, slag, fly ash, etc. The cavities are either continuous or closed. Blocks of closed-cell cavities are laid down. The blocks with closed cavities are laid down by cavities oriented downwards.

Ceramic blocks of older types such as CD-INA, CD-IVA, CD-IZA have been replaced by a new generation of blocks, such as Porotherm, Kintherm or Supertherm, which are produced in dimensional series for single-layer load-bearing masonry. With the latest types, blocks are already filled with heat insulating material (EPS, mineral wool) from production. In addition to the basic elements, additional elements are available - half blocks, end blocks,

Lightweight concrete blocks are manufactured in different strength classes. The products have high precision and can be bonded dry in the head joints without the use of mortar or can be bonded by tongue and groove. Precision calibrated blocks can be glued (joint thickness 1 - 3 mm).

Natural stone masonry is currently not used widely. The disadvantage is mainly its density (2200 to 2400 kg/m³), difficult and costly workability, poor thermal insulation properties and airtightness. The advantage is resistance to weather and mechanical influences and aesthetic architectural effect.

• Random rubble masonry is used for base structures and plinths. The strength of masonry from unprocessed stone is influenced by the quality of its bonding. The joint joints are not to be continuous, the width of the load joints is 15 - 40 mm.
• Squared rubble masonry is made of partially worked stones (squared rubble). Depending on the method of processing, we recognize the rough squared rubble and fine squared rubble. Rough squared rubble masonry may not have the same thickness of the layers and the joints may be oblique. Fine squared rubble masonry is done from fine squared rubble with a clean machined line and the head joints must be vertical.
• Polygonial rubble masonry is used for terrain and decorative purposes. \polygonialmasonry is most commonly used for decorative purposes. The masonry consists of selected stone, which has the shape of irregular four to octagonal. The linkage and bed joints are machined to a depth of about 80 mm and the visible face is left untreated.
• Ashlar masonry is made from machined stones of prescribed shapes and dimensions. Ashlar masonry is used for tiling of representative buildings, monuments, etc.

Mixed masonry is a combination of two or more building materials in one construction unit. Typically, this is a combination of bricks and stones, bricks and concrete, concrete and stone, blocks and concrete. The advantage of mixed masonry is the possibility of using the advantages of individual materials, such as the aesthetic effect of stone on the outer face of the building and high strength of concrete

Keywords: Monolithic structures, prefabricated structures, panels, formwork, column, supporting beam, frame part

MONOLITHIC WALL AND COLUMN STRUCTURES

Monolithic structures are carried out directly on the site by placing a ductile construction material (concrete) into a prefabricated formwork in which the necessary reinforcement is deposited.

Monolithic concrete and reinforced concrete walls

Concrete wall structural system is roughly 10 times more bearable compared to brick masonry system. For monolithic load-bearing walls, heavy concrete (1800-2400 kg/m³) and medium-heavy (1200-1600 kg/m³, eg ceramsite concrete, slag-cement concrete) are used. The concrete has a high compressive strength and transmits tensile stress if it is reinforced. Plain concrete is used only for compressive structures. Reinforced concrete can be used for structures stressed by tension and bending. Heavy concrete walls are usually designed with a thickness of 150 to 200 mm and must always be accompanied with thermal insulation.

Monolithic concrete load-bearing walls are used mainly for civil buildings, for buildings of diverse shapes and complicated floor plans, receding and overhanging structures, high-rise buildings and buildings with high architectural demands.

The concrete mixture is poured into the prepared formwork. Formwork gives the structure a shape and divides it into individual work units. Formwork must allow easy storage of the reinforcement and the concrete mix. Different materials such as wood, steel, plywood or paper are used for formwork. Traditional wooden individual wooden formwork is laborious and uneconomical. Currently, the large-area formwork systems are used. Partial formwork of horizontal plywood or metal or plastic panels with reinforced frame enables multiple uses. The forming system which consists of large panels has different design variants. There is also paper formwork for columns of circular and irregular shapes. The perfectly rigid connection of the concrete walls with the ceiling structure can be achieved by using tunnel formwork, which allows concreting of ceilings and walls at the same time. On high-rise buildings, a sliding or drawn formwork is used, which is formed by formwork panels attached to the lifting frame. Concreting of the walls into the sliding formwork is continuous, the formwork continuously moves vertically at a speed of 100 to 150 mm/hour. Sliding formwork is mainly used in the construction of chimneys, and forces, reinforcement cores. Built-in lost formwork remains a permanent part of the building where it performs the function of surface coating, thermal or sound insulation and fire protection. The construction can also be improved from the thermal insulation by inserting polystyrene boards into a lost formwork. In addition to the cladding boards, reinforced concrete blocks may be used, where the closed cavities with the insulated thermal insulation are cast with concrete dressing. Sheeting cement-bonded bricks with insulated thermal insulation boards as lost formwork.

Surface coating of monolithic walls is made by plastering or facing. The perimeter walls of heavy concrete should be thermally insulated.

Monolithic reinforced concrete column structure

Monolithic reinforced concrete column systems are solid structures made of columns, beams or heads and ceiling structure. The monolithic connection of the vertical and horizontal elements gives the skeleton sufficient stiffness even for high-rise buildings. The advantages of the monolithic skeleton are mainly the integrity of the structure, strength, stiffness and resistance to the effects of extraordinary loads or in the undermined and seismically unstable area.

Columns of monolithic skeletons have squares, rectangles, circles, or composed cross-sections (eg shape I or T). Columns are mainly stressed. However, the monolithic connection with horizontal structures also brings bending stress to them, so they have to be reinforced. The minimum size of monolithic columns is 200 mm. Columns 300 x 400 to 400 x 500 m are usually used in conventional rectangular skeleton structural system. Elements sizes must always be verified by static assessment.

Supporting beams and ceilings beams are also dimensioned based on static calculation. The supporting beam height is approximately 1/8 to 1/12 axis distance of the columns.

Monolithic reinforced concrete skeletons are made as frame, head or slab structures:

• Frame skeleton system: The load-bearing frames can be arranged in the transverse direction, in the longitudinal direction or in the two-way direction (space frames). Supporting beams can be cantilevered in front of pillars.
• Flat slab with column head skeleton system: Flat slab with column head skeleton system is a special case design with two-way arrangements supporting beams. The supporting beams are reduced to heavily reinforced stripes running in the ceilings above the head of the columns. These hidden beams carry a bidirectionally reinforced ceiling slab. Ceiling heads may be rectangular, polygonal or circular. This system is used for objects loaded with large payloads. The disadvantage is complicated formwork.
• Flat slab skeleton system. The slab monolithic skeleton has a ceiling structure directly supported by columns. The slab has a flat ceiling. A flat head is formed around the column. Columns are usually located in a square module network. Ceiling slab should be circumferentially cantilevered that large bending moments are not brought into the outer columns. Skeletons with slab ceilings are used for objects with lower payloads. Their advantage is a flat view, the possibility of free partitioning of the partitions and easy execution.

Column structure systems are also stressed by volume changes due to temperature effects. Expansion joints can be made in reinforced concrete skeletons in several ways:

• Duplication of columns is the most common and most common way of dilatation. The disadvantage of this modification is the interruption of the modular system, which is unfavorably reflected in the front of the building
• Duplication of supporting beams can be done in duplicate. One of the beams is mounted on a column bracket or on the rebate of a neighbouring beam having a higher height.
• The ceiling panel can be created by an inserted field.

PREFABRICATED WALL AND COLUMN STRUCTURES

Prefabricated structures consist of prefabricated full-area or rod-shaped parts, which are bonded to the structure eg by welding, concrete dressing, in the historic stone pillars of 2500 years BC using coupling pins of hard (eg cedar) wood. Prefabricated parts of vertical structures can be made of ceramic, heavy or lightweight concrete or steel. The rigid connection of reinforced concrete columns with supporting beam (welds + concrete dressing) formed frames that are the basis of prefabricated skeletons.

Prefabricated concrete reinforced concrete walls

The load-bearing walls of the prefabricated elements began to be widely used in the 1950s. The first prefabricated panels were made in the form of blocks and blocopanels, later in the form of panels:

Blocks are wall element panels, their height is ½ to 1/3 of floor height, thickness 300 to 400 mm. Blocks were made of crushed concrete, slag-cement, porous concrete, and they are placed in a mortar bed. Block constructions were referred to as a semi-assembled system. They are currently used only exceptionally in the reconstruction and adaptation of apartment buildings.

Blocopanels are wall element of floor height and a width of 1200 to 1500 mm. The thickness of the blockopanels is given by mechanical and thermal-technical properties (250 - 400 mm). They were made from the same materials as blocks. In the wall constructions, they were joined by welding reinforcement and grouting of joints.

Panels are large-area panels whose dimensions are limited by the characteristics of the material used and the lifting device's load. Wall panels typically have an area of 10 to 20 square meters. The height corresponds to the height of the floors. Their usual 150 mm thickness meets acoustic and fire protection requirements. Wall panels are made of concrete, reinforced concrete, lightweight concrete, ceramic blocks or as a layered element (sandwich construction).

Depending on the layout of the load-bearing walls, we recognize transverse, longitudinal and bi-directional systems. Depending on the function, we are able to distinguish the interior load-bearing wall panels and the peripheral load-bearing wall panels. Internal load-bearing panels are produced in thicknesses of 150 - 200 mm and in a length of multiple 300. Wall panels may be full or with holes. Concrete panels must have a structural reinforcement that is particularly relevant for transport and assembly. The interlocking is provided by the contact reinforcement in the form of steel pins, loops or steel joint plates. In addition to the static function, the perimeter wall panel must fulfil the thermal insulation function in particular. Both of these functions can be fulfilled by the single-layer panel. However, it is preferable to manufacture a two-layer or three-layer sandwich panel. Single-layer panels are made of lightweight concrete and hollow ceramic inserts. The two-layer panels have a concrete or reinforced concrete support layer and an outer layer of lightweight concrete or ceramic materials. The three-layer panels consist of a reinforced concrete or reinforced concrete board with a thickness of 100 - 150 mm and a thermal insulating core (polystyrene, mineral wool). The stiffening panels form an internal reinforcing wall, which provides stability prefabricated buildings. The stiffening walls are not loaded with ceilings, but they are stressed by carrying the effects of horizontal forces. Their thickness varies from 80 to 100 mm.

Prefabricated reinforced concrete column structure

Prefabricated reinforced concrete skeletons have evolved from monolithic structures. The first assembled skeletons appeared in the 1930s. During the development, more than 30 systems of prefabricated skeleton systems were built. Many of these systems have been unified and replaced by a unified system - an open set-up system of assembled frame skeletons characterized by the unified principle of supporting beams and columns that are still in use.

Frame assembled skeleton is made up of supporting beam mounted on columns. Frames are formed by dividing the monolithic frame off its joints, at the sites of the smallest bending moments. In columns, it is usually a half to a third of their height. For beams is in a quarter to a fifth of the span. The H-frames are formed in such a division and retaining the rigid joints. The frames П are created by dividing the columns in the heel. Console columns and split beams are formed by separating the beam from the columns on which the brackets remain. Columns with continuous beams are formed by dividing monolithic skeletons in the joint. Supporting beams are interconnected either directly above the columns, or extend over the columns and contact the field. The basic connections include the intersection of two columns, the intersection of two beams and the contact of the beam and the column.

Keywords: Opening, jamb, head of openings, ledge, niche, monolithic lintel, prefabricated lintel

The openings in the walls and partitions are designed to illuminate the room with daylight and to connect the adjacent spaces or outer environment with the interior of the building.
The wall openings are divided according to their purpose:

• Window openings that perform lighting and room ventilation functions
• Door openings that function as a room entry and room connection
• Gate openings which are used for vehicle entry
• Passes are openings without filling
• Other openings such as niches

All openings have head of openings and jambs. The jamb is the lateral surface of the opening in the wall. The jamb may be straight or craned. The head of opening is the construction above the opening. The window openings also have the window sill (window ledge). The window ledge is the bottom part of the niche and the entire lining under the window, that is, the wall from the floor to the window. The niche is usually a decorative recess in the strength of the building's brickwork. Door and gate openings have a threshold at the bottom or they are without a threshold.

The lintel must be placed over the openings. The lintel must be able to transmit the load from the adjacent part of the ceiling and walls to the vertical support along the opening.

Requirements for the lintel:

• Static requirements - Load transfer to support
• Compositional - In the case of assembled lintels, the dimensions must correspond to the compositional dimension of the vertical structures and ceilings
• Thermal insulation requirements - to ensure the minimization of thermal bridges

Loads of lintels may be equally continuous (e.g. reinforced concrete slab) or with the group of solitary loads (e.g. beams). According to the position of the load, there are one-sided load eccentricity (the peripheral wall) and a load-sided (at the middle of the wall). Depending on the shape of the centerline, the head of opening can be straight (pressed or bent) or arched (strain dependent on pressure or flexural pressure).

The lintels must ensure the transfer of loads to the adjacent supports. The loading effect on lintels is not constant, but usually triangular. The size of the displacement angle depends on the stiffness of the wall and its height above the lintel. Thermal bridges must be excluded in peripheral structures. Modern lintels made of reinforced ceramic blocks or porous concrete have the supporting function and thermal insulation function.

According to the technological implementation, the lintels may be monolithic or prefabricated. Prefabricated lintels can be stone or brick, from steel beams or from ceramic block beams. Prefabricated translations are reinforced concrete or lightweight concrete.

The direct stone lintels are made up of precisely placed bevelled blocks and connected by stoneware clinch. The arched stone lintels consist of stone vaults of different shapes and sizes. Due to the great difficulty in realizing the stone lintels and due to the insufficient thermal insulation of the stone, at present, the stone lintels are not used in new constructions.

The lintels from stone blocks should have upper and lower obverses horizontal. The lintel line is wedged from both sides and closed with a central voussoir, the joints are straight or oblique.

The direct reinforced lintels use tape steel to transfer the tensile stresses in the lower face. Arched lintels into the foot are either common bricks with a wedge of mortar or sliced conical bricks. The static effect of the lintels is similar to the vaults, with a span of about 3.0 m. The head joint formed by the wedge of the mortar has a minimum width of 8 mm and a maximum of 20 mm. Joints wider than 20 mm are wedged by flat fragments of bricks or roof tiles. The crushed bricks must have a minimum thickness of 45 mm.

Simple brickwork head of openings is done as a reinforced brick lintel. It is made as a straight vault made of hard bricks and reinforced in the joints by a 20/1 - 30/2 mm strap taking the pull at the bottom of the lintel.

The brick strip is vaulted in the wall thickness on the wooden, or mortar, shoulders. It is suitable for smaller spans and for the head of openings without indentation. The masonry is done from the foot towards the center. The direction of the joint is controlled by a template or a lath. The slope of the raised or recessed foot is determined by a center angle, preferably 30 °.

The steel lintels from rolled I-beams are used for heavy loads and large spans (up to 6 meters) as well as for renovations. The advantage of steel lintels is their ability to transfer loads immediately. The supporting length is affected by the overall length of the beam and the load, but at least 150 mm.

The lintels from steel beams are made of rolled profiles laid on concrete or stone bed foundation. The embedded traverses are either concreted or encircled by bricks and wrapped in ceramic or rag-mesh and plastered (fire protection). These lintels should be additionally insulated by thermal insulation to avoid the thermal bridge.

Ceramics have the low tensile strength and thus ceramic lintels are complemented by the reinforcement in ceramic blocks. Ceramic shaped brick acts as a lost formwork. And also forms a suitable base for plastering. Ceramic lintels parts are manufactured in various shapes. The ceramic parts are placed vertically into a prepared bed of cement mortar (supporting length 150 to 300 mm). In the perimeter walls, they are combined with a thermal insulator.

Lightweight concrete lintels can be made from porous concrete, ceramsite concrete and other materials. The lintels from lightweight concrete can be box, roller, segment or arc.

The lintels from lightweight concrete are used in most cases for brickwork made of blocks of the same material. Flat load-bearing porous concrete lintels are supporting elements reinforced by welded concrete reinforcement. They have excellent thermal insulation properties and are therefore a suitable supplement to massive masonry made of aerated concrete without changing the underlying material for plastering and with minimal thermal bridges.

Prefabricated reinforced concrete lintels are assembled from prefabricated rod-shaped elements of which it is possible to compose multipart lintels. The lintels are made in lengths from 1.2 to 3 meters. The supporting length of the lintels is given by the width of the lintel, but not less than 150 mm. Prefabricated reinforced concrete lintels can be loaded immediately after installation.

Monolithic reinforced concrete lintels are applicable for any load range. The advantage of monolithic lintels is their shape and dimensional variability. The disadvantage is considerable labor, the need for formwork and the possibility of loading until the concrete is hardened. Monolithic lintels may act as a single beam over one or a continuous beam over multiple openings. If the head of the opening is closely related to the ceiling structure, the monolithic lintel can be associated with the reinforced concrete rim. Support of monolithic lintel should be at least 7,5% clearance opening (minimum 200 mm). The reinforcement of the translation must correspond to their static effect.

Chimneys are among the most stressed building elements - they are exposed to extreme temperature conditions and aggressive flue gases.

The chimney consists of:

• One or more chimney flues
• Chimney casing
• Sweep openings
• Pickup openings
• Vent connector
• Chimney heads, or extensions

• Solid fuel chimney
• Liquid fuel chambers
• Gaseous fuel chimney

• Single-layer chimneys - The chimney's passage is formed by a chimney casing
• Multi-layer chimneys - The chimney consist of a structure consisting of a chimney liner, an insulating layer and a chimney casing

• Fitted or built-in chimneys
• Solitary chimneys

• Square chimneys
• Rectangular chimneys (up to 1: 1.5)
• Circular chimneys

• Narrow chimneys (up to 40,000 mm²)
• Medium chimneys (over 40,000 mm²)
• Man chimney (minimum cross-section up to 10 m high is 450 x 450 mm)

• Chimneys made of non-flammable or non-easy possibly flammable materials
• Chimneys made of materials with an absorption capacity not exceeding 20% of the specific weight
• Chimneys made of materials resistant to the effects of flue gases
• Chimneys made of frost-resistant materials

• Continuous chimneys
• Storeys chimneys
• Overflow chimneys
• Tree chimneys

• Direct chimneys
• Moving chimneys

The flue gas is exhausted by chimney flues formed in the chimney casing. The hole through which the flue gas is fed into the flue is called the vent connector. Other openings in the chimney enclosure are used for cleaning the flues - pickup hole and sweep hole. The chimney ends the chimney head.

The chimney draft depends on the difference in mass of hot combustion gases and fresh air in the chimney head. The draft of the chimney also depends on the size and shape of the flue, on the smoothness of the interior surface of the flue, and also on the effective height. The effective height is part of the chimney from the chimney to the chimney head and is intended for flue gas removal. Part of the chimney from the flue connector to the chimney soil is used to collect solids of flue gas and condensate.

The chimney flue should have a constant cross-section along the height. Chimneys may contain flue for exhaust gas and may have ventilating vents (vents). Flues for exhaust gas cannot be used as ventilation vents and vice versa. Flues are designed generally vertical and straight. Any deviation from the vertical should not be greater than 15°. The flues may have a square, circular or rectangular cross section.

The chimney casing should be non-flammable, low absorptive and resistant to flue gases. The chimney passing through the interior or building structure shall not have an outer surface temperature above 52°C during operating. A part of the chimney directly exposed to atmospheric influences should be protected from freezing.

Single-layer chimneys must have a masonry chimney thickness of at least 140 mm. The curvature of chimney's flue shall be formed by a smooth curve with a radius of at least 300 mm. The outer surface of the monolayer masonry chimney can be plastered or sprinkled, or fitted with a non-flammable coating.

Multi-layer chimneys are usually three-component. They are consisting of chimney liner, an insulating layer and a chimney casing.

Openings in the chimney must always be accessible. The flue connector is part of the chimney, which connects the appliance and the chimney flue to which the exhaust gas. The flue connector cannot be larger than the light cross section of the flue into which they are inserted. The flue connector should be direct and toward the flue should rise. Sweep openings are designed for flue and liquid fuels that cannot be swept straight through the chimney head. The holes are placed over the roof or in the attic. Pickup openings are designed at the level of the soil of the chimney flue. The floor around the selection holes must be non-combustible. All chimney openings should be closed with chimney door made of non-combustible materials.

Chimneys are positioned above the roof so high that they do not disturb the environment or pollute the surroundings with flue gases. The smallest permitted chimney height is given by the type of roofing and the location of the chimney