The structural system may be composed of three basic types of structures.
A structure is an arrangement and organization of interrelated elements in an object or system, the load may have a vertical or lateral impact on structural components.
Different types of structures:
1.Load bearing structure:
In this type of construction, the weight of the structure is transferred to the walls in the form of roofs, floors supported directly on the walls.
The walls transfer the load to the underlying soil through wall footing.
This types of structures is suitable and economical for two to four storeys.
As the number of floors increases, the wall thickness also decreases the carpet area due to its load-bearing function.
As wall footings are rested directly on the hard strata, this type of construction is adopted where hard strata are available at shallow depths.
These days only temporary or less important structures are constructed in load-bearing.
Advantages of Load bearing structure:
- The load-bearing masonry structure constructed is highly durable and solid.
- This types of structures have high fire resistance.
- Masonry units are available in various colours and textures which gives freedom of creativity.
- This type of construction does not require advance preparation.
- Load-bearing masonry structures are aesthetically appealing.
- Tools and equipment used for masonry construction are simple and cheap.
Disadvantages of Load bearing structure:
- The load-bearing masonry structure performs poorly during earthquake action.
- Load-bearing masonry construction employs more labour.
- This masonry construction is slow.
- Load-bearing structures consume a large number of masonry units.
- The cost of the total masonry units used to construct these structures makes it unreliable.
- The weight-bearing masonry structure has more weight.
- The thermal insulation properties of these structures are very poor.
In this framed structures, the load is transferred to the underlying soil through a frame of slabs, beams, columns and footings.
The slab and beam are flexural members in which the slabs resting on the beam.
The beams transfer the load to the columns, which are eventually connected to the footings resting on the soil, carry the load to the hard strata.
Types of framed structures:
1. Light-frame structure:
The light-frame material is most often wood or rectangular steel, tube or C-channel.
Pieces of wood are usually attached fastener nails or screw-steel pieces are attached to nuts and bolts.
Exterior finishes for walls and ceilings include plywood or composite sheathing, brick or stone surfaces and various plaster finishes.
Interior wall coverings in a light-frame structure typically include wallboard, plank and plaster, decorative wood or fibreglass panelling.
In natural buildings, straw bales, cob can be used for both exterior and interior walls.
The light-frame structures are built above the basement with a crawlspace,wood or steel which extends between the foundation’s walls they are usually constructed of powdered concrete or lightweight concrete blocks.
The use of minimal structural materials allows to enclose a large area with low cost.
The wood-framed construction is the most popular type of buildings used for homes in the United States and some parts of Europe.
2. Timber Structure:
In timber structure, various structural members such as joysticks, studs, rafters, purlins, etc. are mainly made of wood materials which have good compressive, tensile and flexural strength.
There are two types of timber frame structures such as balloon frame structure and platform frame structure.
The platform frame structure can be used to erect a two-story platform frame house, they are better than the balloon levelling structure.
3. R.C.C. Frame Structure:
R.C.C. framed structures are a very common type of framed structure used in modern buildings.
Reinforced cement concrete (R.C.C) is concrete that consists of steel bars called reinforcement bars or rebars.
This types of structures consisting of a frame or skeleton of concrete consisting of steel bars, the horizontal members are called as beams and the vertical members are called a column.
Various main structural members such as slabs, beams, columns, footings etc. are strongly interconnected.
In short, the RCC framed structure is basically firmly attached to each other as a unit of slab, beam, column and foundation.
These structures are capable of resisting various loads such as dead load, live load, dynamic load, wind load, earthquake-load.
Monolithic construction is possible with RCC framed structure.
These types of structures can resist vibration, shock, earthquake, wind load, live load, etc.
Advantages of framed structure:
- Columns and footings are compression members of the frame.
- The walls do not carry loads except for their self-weight which is transferred to the beam on which they are supported, thus the walls serve only the purpose of enclosing the structure.
- This types of structures can be multi-storey, more than 100 storey buildings can be constructed.
- The frame can be constructed using reinforced cement concrete or steel.
- Construction speed is faster than load-bearing construction.
- Due to the use of precast concrete members and ready mixed concrete the speed of construction can be further increased.
- If rigid wires are not available at considerable depth, pile foundation or raft foundation may be employed which id advantage over load-bearing construction.
Disadvantages of framed structure
- Spans greater than 40 feet can cause lateral deflections.
It is a combination of load-bearing structure and frame structure.
Exterior walls may be of a load-bearing type, while column and beam structures may be provided internally, thus floors and ceilings are supported by walls and frames.
These types of structures are generally adopted for industrial sheds or warehouses where spans are very large.
Advantages of Composite structure:
- Composite structures are highly resistant to heat and electricity.
- Composite materials are lighter weight than traditional materials, so the structures made of composites are easy to carry and install.
- This types of structures are flexible, engineers can design structures according to their requirements.
Disdvantages of Composite structure:
- Construction of these structure are highly economical.
- It requires skilled labour for construction.
Difference between composite, frame & load-bearing structure:
|Aspect||Load Bearing||Frame Structure||Composite Structure|
|Soil Condition||Hard strata are available at shallow depth.||Suitable for any type at any depth.||Hardening wire required at shallow depth.|
|Floor space||Low floor area is available due to thick walls.||More floor area due to thinner walls.||Intermediate floor area is available.|
|Height||Up to 4 storeys are allowed.||Multistoried construction is possible.||Mostly 2 storey structures.|
|Time||Slow and time-consuming construction.||Less time is required.||Intermediate time is required.|
|Economy||Affordable up to 2 storeys.||Economical for multistoried floors.||Less expensive than frame structure.|
|Flexibility in planning||Less flexible due to load||Flexible due to walls serving planning as partitions only||Internal arrangements can be modified|