improving the punching strength prediction relation of aci for r/c bridge deck slabs

some problems arise in designing of r/c structures are due to lack of information on shear behavior and yield-shear(shear-flexure) of slabs. two types of shear failure modes are possible in two-way slabs, each of which should be controlled separately. the direction of principle shear flow is extremely variable and circular cracks are developed around concentrated loads in two-way slabs. parallel shear flow occurs in one way shear around supports, whereas tow-way shear is more possible. in this paper, the behavior of the deck slab under concentrated load studied numerical using atena software which was tested by rodrigues. the result shows that the modes of slab failures can be observed somewhere between one-way shear and punching shear. in this failure, the shear cracks are a combination of radial and tangential cracks. although, developed for some form developed for one-way and two-way failure load prediction, yield-shear (shear-flexure) have not been completely covered in codes. in this study, adding factor for the critical perimeter has been modified in order to calculate such failure in the aci code. results show that yield-shear (shear-flexure) can be estimated by adding modification factor considered in aci.