Experimental Study On Shear Failure Of Large Span New Prestressed Concrete Composite Hollow Slabs

In recent years, the floors of the modern building (especially the residentialstructure) have been designed with large span and over-loading. Cast-in-situ concretehollow floor is a new floor proposed under that demand, which is poure d based on theinner core (made of permanent light materials).Presently, the shear failure tests ofcast-in-situ concrete hollow floor have been carried out by researchers at home andthe correspondingly computing methods have been obtained, but it is still in theexploratory stage. The conclusions of the researches and experiments aboutcast-in-situ concrete hollow floor from the abroad scholars are not identical.Especially, there isn’t a mature design method for the shear capacity of cast-in-situconcrete hollow floor.Based on the researches of composite slab in Hunan University, the thesis putsforward the large span new prestressed concrete composite hollow slab and six testspecimens are taken for the shear failure tests. The load-deflection curve and theload-strain curve are obtained based on test phenomenon and test data. Meanwhile,the diagonal cracking load,shear capacity and the relevant strain of stirrup aremeasured. Afterward, the influences of the following parameters, such as, the width oflongitudinal rib in the slab, the diameter of the inner core, the width of transverse rib,the arrangement type of pipes, the combined interface, the pouring way and thestirrup on the ultimate shear-resistant capacity and shear ductility are analyzed indetail. Three main failure modes exist in the test, that is,bending shear failure,diagonal tension failure and shear failure.Eventually on the basis of experimental statistics, the calculating formula s of theultimate shear-resistant capacity of the large span new prestressed concrete compositehollow slab are obtained according to the existing shear stress model of hollow floorstrip. In the light of the formula, the shear capacity of test specimens closely meetsthe experimental result. Therefore, It can be regarded as the prediction formula for theshear capacity of the large span new prestressed concrete composite hollow slab.