Strengthening Methodology for Lightly Reinforced Concrete Frames

摘要

To develop an analytical tool for assessing seismic performance of strengthened lightly reinforced concrete (LRC) frames, hysteresis failure models were developed and incorporated into computer program IDARC for dynamic analysis of LRC frames. The models were developed by, first, using the system identification techniques to characterize the load-deformation histories of LRC frame tests in terms of the stiffness degradation alpha, the strength degradation parameter beta, and the pinching parameter gamma. Next, multi-variable regressions were performed to relate alpha, beta, gamma as functions of the specimen's material and geometric properties and reinforcement parameters. The empirical expressions resulting from these regression analyses are the hysteresis failure models. The models were validated against experimental results and used in a parametric study to evaluate the influence of certain variables to the behavior of infilled LRC frames. The variables included the thickness of infilled wall, the amount of reinforcement in infilled walls, and the area of anchors which connects the infilled wall to the fame. General design guidelines are proposed.