Theoretical Analysis Of Composite Beams With Cast-in-place Concrete Slabs On Precast Prestressed Concrete Decks

A new type of steel-concrete composite beam was developed recently for modular construction,which adopts Precast Prestressed Concrete Decks(PPCDs)as an alternative to steel corrugated decks.In a typical composite beam with PPCDs,the PPCD segments are placed on the steel beam and work as the permanent formwork.Through application of appropriate connectors between steel beam and concrete slab,their relative slip can be restrained,enabling shear force transfer between them and achievement of the composite beam action.This research introduced the recent development of conventional composite beams in modular construction and then summarized the advantages of the composite beam with PPCDs.In addition,construction and practice of such composite beam were listed in detail.in this paper.To evaluate the flexural behaviors of the composite beam with PPCDs,this research developed an analytical model for such composite beam which was subjected to two downward point loads.Considering effects of PPCD joints,the precast ratio and the interface slip,the generalized effective rigidity was derived from the internal force equilibrium and curvature compatibility of the steel beam and composite slab segments.Research also developed the calculation methods for interface slip,elastic curve along beam longitudinal direction and flexural resistance at elastic limit.Besides,a simplified analytical model based upon an assumed stress diagram was found to provide reasonable predictions for ultimate flexural resistance of such composite beams.Additionally,four-point bending tests including ten full-scale specimens were carried out to evaluate the adequacy of derived models.Specimens CB1-CB9 were composite beams consisting of PPCDs while Specimen CB10 was a composite beam with a full-depth cast-in-place included here for comparison purpose.Based upon the test results,this paper also evaluated the influence of some key design parameters(e.g.,concrete slab thickness,amount of shear studs and longitudinal reinforcement ratio)on flexural performance of the composite beams.In comparison with the experimental data from ten specimens,the developed calculation models met prediction accuracy and could help promote the applications of such composite beams in future building constructions.Furthermore,this paper explored the slip distribution on the interface between steel beam and concrete slab.The precast ratio was regarded as a key parameter and the paper investigated the influence of precast ratio on the flexural behaviors of composite beam with PPCDs when it varied.