Research On Behavior Of Ribbed Concrete Composite Floor Slabs With Steel Bar Trusses

Ribbed concrete composite floor slabs with steel bar trusses is a new type ofcomposite structure. It fixed the steel truss which processed in the factory on thetemplate, then pouring the concrete in, made into ribbed concrete precast slab with steelbar trusses, without falsework and formwork under construction, Finally, pouringconcrete composite layer after precast slab craned designated spot under construction.This slab is divided into two stage production and secondary load.The behaviors of concrete ribbed composite floor slab with steel bar truss underconstruction and serviceability stage are analyzed by the test. Result shows that whetherthe performance of floor slab meets specification requirements controlled by short-termstiffness of precast slab, rather than bearing capacity. If short-term stiffness of precastslab meets specification requirements under construction, the stiffness and bearingcapacity of composite slab will have a lot of margin in serviceability stage.Nonlinear finite element software ANSYS was applied on validation andparameters analysis of ribbed concrete composite floor slabs with steel bar trusses.Analysis shows that the height of trough have a significant influence on the short-termstiffness of the composite floor slab under construction, the width of trough is poorer.The height of truss, diameters of top and bottom chords, have a significant influence onthe short-term stiffness of the composite floor slab under construction. Change of webmember diameter has no influence on mechanical performance of slab, design need tomeet the detailing requirements under construction. It is obtained by finite elementanalysis, finally, common choose table span of ribbed composite floor slab with steelbar truss.At last, combined with the results of test and numerical analysis, based on the flat section assumption, considering steel truss and concrete trough on the slab sectionstiffness contribution, through certain simplifying assumptions theory, proposed thecalculation formula of short-term stiffness of ribbed composite floor slab with steel bartruss under construction and serviceability stage.