Numerical Study of Masonry-Infilled RC Frames Retrofitted with ECC Overlays

摘要

This paper presents a nonlinear finite-element modeling method to evaluate the seismic performance of reinforced concrete (RC) frames that have unreinforced masonry infill walls retrofitted with engineered cementitious composite (ECC) overlays. The method has been validated by results of shake-table tests conducted on a 2/3-scale, three-story, two-bay, infilled frame. Results of a numerical study conducted with the validated model have provided further insight into the performance of a structure retrofitted with this technique. A simplified analytical method to assess the shear capacity of an ECC overlay and determine the number and size of shear dowels required to prevent dowel failure has been proposed to ensure a more ductile behavior of the retrofitted structure. Results have shown that the performance of a retrofitted system can be greatly improved by preventing dowel failure so that the benefit of the ductile inelastic behavior of the ECC can be fully exploited. Furthermore, methods to estimate and account for the influence of the construction sequence and material creep on the distribution of gravity loads between the RC columns and infill walls in a finite-element model are presented.