MODIFICATION OF SEGMENT EQUILIBRIUM METHOD THROUGH CONSIDERING TENSILE MEMBRANE EFFECTS AND ITS APPLICATION IN TWO-WAY CONCRETE SLABS

Tensile membrane effects commonly appear when steel reinforced concrete (RC) slabs at large deflections. Based on classical yield line theory, tensile membrane effects cannot be well taken accounted by a segment equilibrium method. To solve this problem, a modified segment equilibrium method is presented for considering tensile membrane effects. The full response of RC slabs under static loading is divided into two stages as that before and after yielding. RC slabs are assumed to stay elastic before yielding, and yielding deflection and load-carrying capacity are determined by Navier method and segment equilibrium method respectively. For a post-yielding stage, the tensile membrane effect is assumed to be provided by the vertical component of forces in steel bars along the plastic hinge sections, and the horizontal component of steel forces and the compressive forces of concrete form a section resistant couple. Due to above modification, the entire load-deflection curves that incorporate tensile membrane effects can be generated. To validate the presented method, four two-way RC slabs are selected as study cases. It is shown that the analytical results agree well with the experiment data, which confirms the validation of the modified segment equilibrium method.