Proposed theory to determine the horizontal shear between composite precast and in situ concrete

A theory is proposed to determine the horizontal shear between the roughened interface of a composite precast member and in situ concrete. The proposed method is completely congruous with the alternative method listed in clause 17.5.3 of ACI 318-95. The horizontal shear is determined by calculating the change in the tension force across an elemental segment at the point maximum shear will occur. This approach differs from prevailing methods which base the horizontal shear as a function of the mid-span ultimate force. Equations are developed for both cracked and uncracked sections. Experiments were also performed to validate the proposed equations.