Seismic behavior of non-rectangular RC walls with inferior details subjected to loading from different direction
Date of Issue2015
School of Civil and Environmental Engineering
Non-rectangular reinforced concrete (RC) structural walls are commonly adopted in buildings. These walls are important structural elements in resisting lateral load imposed by wind or earthquake. As these walls possess significant lateral stiffness in multiple directions, they are expected to resist large lateral load in multiple directions in an earthquake event. Contrary to their popularity, experimental data regarding these walls are limited. Several problems regarding behavior of these walls remained unclear and there were no experimental data regarding behavior of these walls with inferior details. This study aims to provide experimental evidence to behavior of L-shaped and T-shaped walls with limited transverse reinforcement and to contribute to the design method of non-rectangular RC walls. This thesis comprises two parts. In the first part, the experimental investigations conducted in Nanyang Technological University were reported. The experimental investigations include testing of 8 L-shaped walls and 6 T-shaped walls. These walls were designed for moderate ductility and went through an axial load together with cyclic lateral loads simulating the earthquake loading. The variables of interest included the axial load ratio and the loading directions. The setup of the experimental programs was given and discussed. The experimental results were presented. The specimen performances were analyzed and discussed in terms of failure mechanisms, cracking patterns, hysteretic responses, curvature distributions, displacement components and strain profiles. In addition, the experimental results were compared with the estimates of various existing design tools and methods. The second part of the study addressed the two problems associated with current design methods exhibited in the experimental study. First, a new method was developed for considerations of the shear lag effect in tension flange of non-rectangular RC walls. The method was deduced based on the truss analogy. For validation of the method, predictions of the proposed method for numerous non-rectangular RC walls with different design parameters were compared with the analytical results of sophisticated finite element (FE) models of these walls. These comparisons demonstrated that the proposed method is capable of predicting the influences of the shear lag effect in tension flange of non-rectangular RC walls with common design parameters. Comparisons of the proposed and current method demonstrated that the proposed method possess significant improved accuracy. In addition, discussions and validations were given regarding the applicability and the conservatism of the proposed method. Second, a solution based on Timoshenko’s beam theory was given to explain the out-of-plane curvature observed in the specimens loaded in the non-symmetrical loading directions. The solution indicated that for RC walls expected to bend around the non-principal axes, the out-of-plane curvatures and deflections can be quite significant depending on the shear deformations of the wall in different principal loading directions.
DRNTU::Engineering::Civil engineering::Structures and design