Investigation of seismic performance for low rise RC buildings with different patterns of infill walls

Abstract

Evaluating the structural performance of low-rise RC buildings with infill walls is an essential issue in Thailand as most were not designed for lateral load resistance. The purpose of this study was to predict structural behavior and illustrate the effects of infill walls. Residential, commercial, and educational buildings were selected as representative buildings with different patterns of infill walls. Based on the results, infill walls contributed to considerable strength and stiffness, depending on the presence of infill walls. Most of the infill walls that affected the low-rise buildings were at the ground floor level. The behavior of the buildings that had a contribution of infill walls was found to be brittle until the infill walls collapsed, then became ductile. Some patterns that infill walls were placed improperly led to a torsional effect, resulting in columns in the affected extent reaching failure criteria than that without this effect. Considering the NLRHA procedure, only infill walls on the ground floor contributed to the building being subjected to a ground motion. The fully infilled frame tended to reach infill crack before other patterns. For the UMRHA procedure, only the first vibration mode was adequate to predict seismic responses, such as roof displacement and top story drift. IMPLICATION OF THESIS: Recommendations for future research 1. Frame model should account for as many as possible failure modes. For instance, shear failure should be included in the modeling of frames. This is essential when a single strut in the considered direction fails, high shear demand in the column next to that strut can be observed. As a result, the shear failure mechanism can be taken place owing to the short column effect. However, any failure mechanisms can occur. If only some failure mechanisms are considered, this might lead the frame to be stronger than the actual one. The more failure mechanisms are accounted for, the weaker the frame is and the more realistic it becomes. 2. It is interesting to allow other patterns of infill walls, especially for the interior portion. It might be possible that placing some infill walls in the interior portion will lead to strength and stiffness as high as in the exterior portion. Infill walls with openings should also be considered since they cause a reduction in strength and stiffness. 3. Tuning actual cyclic pushover curves and idealized curves is important, so other hysteretic models apart from the modified Takeda model should be considered. It is found that not only the hysteretic response in the large deformation is crucial, but also one in the small deformation. This might lead to more accurate results in terms of estimating seismic responses.