Experimental and theoretical research of the punching shear performance of steel-normal concrete-UHPC composite slabs

The use of UHPC enables reducing the height of composite slabs, which may decrease the punching shear capacity. This paper investigates the punching shear behavior of steel-normal concrete-UHPC composite slabs with experiments and theoretical analyses. Results indicated that a 50 mm UHPC layer makes the nominal punching shear strength increase by 24.91%. Utilizing UHPC and increasing loading area can effectively enhance the punching shear capacity. Besides, theoretical punching shear model proposed based on rigid-plastic theory can reliably predict the punching shear capacity of composite slabs. The punching shear angle derived from strength theory closely matches the experimental values.