Composite construction
Advantages of composite floors
Composite floors offer significant advantages related to speed of construction and reduced overall construction depth.
Bending strength of composite beams
Calculation procedures can be used to determine the bending strength of a composite beam; simpler methods can be used to estimate beam sizes.
Composite beam construction with alternative forms of floor slab
The behaviour of composite beams described above relates to simply supported beams and insitu solid concrete slabs. Where other forms are used this may be slightly modified, although the principles and advantages of composite action remain.
Composite floors using conventional shallow decking
In composite floors, steel decking acts as reinforcement to the concrete and supports it during construction when it is wet.
Connection between beam and slab to achieve composite action
The connection between beam and slab is typically made using a number of stud connectors welded to the top flange of the steel beam.
Construction issues relating to shallow deck composite floors
Because composite floors have a maximum span of about 3.5m, the supporting structure is generally based on a system of secondary beams at corresponding centres.
Deep deck composite floors
Deep deck composite slabs are about 200-300mm thick with a maximum span of about 8m.
Deflections of composite beams
Modified calculation methods can be used to determine deflections of composite beams, but simpler procedures based on limiting span:depth ratios are often adequate.
Design principles for composite beams
The slab thickness is determined by its function as a floor, and the composite beam design is therefore concerned with sizing the steel section.
Flexural strength calculations for composite beams
The design of composite beams for bending is based on a comparison of ultimate bending strength and the applied bending moment under factored loads.
Influence of the construction sequence on the deflection of composite beams
Deflections which occur during construction before composite action has developed contribute to the total deformation.
Introduction to composite construction
The principle of composite construction is to use different materials in combination to make best use of their particular characteristics.
The principle of composite action
The principle of composite construction can be demonstrated by comparing the action of two joists placed one on top of the other. If these are physically connected the bending strength and stiffness are significantly improved.
