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.