Self-supporting Steel Truss Concrete Composite Board Design Calculation Method

Composite slab by steel bar truss and concrete is a new style of floor slab. Because there are the small steel bar trusses in precast member, its short-term rigidity is higher than the normal composite floor slab. This kind of structural system has its advantage and feature that it doesn't need template and temporary construction supports at slab bottom. It is especially fits for factory-prefab beam and pillar in steel structural house, fixing members on spot and the requirement of fast construction.Based on the existing theories of flexural members in the country and abroad, the author developed different formulas to calculate short-term rigidity of precast member, according to the flow point. 1. Relative location of the neutron-axis and the combined interface of slab; 2. Relative value of the moment in first phase and the cracking moment of the precast slab. After the calculation formula of slab short-term rigidity is found, the author research the calculation of the stress of bottom steel bar, long-term rigidity, the width of crack, the pressed steel bar's length supported by the web member, and the hoist of the precast slab. After these, all design theories of the Composite slab by steel bar truss and concrete calculate as one way slab is found.Then the influence of several parameters to the short-term rigidity of precast slab is analyzed, such as the thickness of precast slab, the axis distance between the top member and the bottom member, concrete strength, the radius of web member. And compare the FEA result to the theory result.At last, a design example of composite slab by steel bar truss and concrete as one way slab(simply support slab in first phase, continuous slab in second phase) is present, in order to exhibit the all steps of the design. A little computer program is edit to design the usual span slab in building construction based on the rules of bearing capacity and normal limit state. The usual span slab (600mm width) is completed in chapter 4. The result is list in order to easily choose in the latter design.