3rd Croatian Conference on Earthquake Engineering 3CroCEE

For high-rise buildings, reinforced concrete (RC) shear walls have emerged as a preferred structural element due to their significant contributions to global lateral strength, stiffness, and ductility. The lateral stiffness RC structural walls provide to the building system effectively mitigates structural and non-structural damage by limiting excessive deformation. Therefore, accurately estimating the effective stiffness of structural components under design basis earthquake is crucial for determining the design forces on various structural elements and for assessing the global drift of the building system. Under design basis earthquake the concrete will crack over a significant portion of the shear walls and the reinforcement will yield in concentrated locations, and thereby there is a reduction of the initial uncracked stiffness. Various international standards and design codes have prescribed effective stiffness of the RC structural wall as a constant reduction factor to the gross moment of inertia of the wall section. Two major limitations of the constant reduction factor prescribed by current design codes are the lack of identification of the key parameters that influence effective stiffness and the inability to consider the geometrical shape of RC structural walls. The present study has tried to address these two major gap areas. In the current study, a flanged RC structural wall from a previous experimental study was selected, and a finite element (FE) modeling approach was employed to develop the numerical model. Displacement-controlled nonlinear static analyses were conducted, and the accuracy of the developed FE model was evaluated based on the response obtained from the numerical study and the past experimental result. From past studies on rectangular and non-rectangular RC structural walls, the major influencing parameters related to the effective stiffness of the RC structural wall were identified. Based on the determined parameters, a parametric study was conducted, and finally, an empirical equation of the effective stiffness of the L-shaped wall was presented. The accuracy of the empirical equation was assessed by estimating the coefficient of variation (COV) between the predicted effective stiffness and the FE model-derived effective stiffness.