Multi-bay and pinned connection steel infilled frames; an experimental and numerical study

Abstract

The equivalent diagonal strut is one of the most prevalent approaches to model the infill panels recommended by many seismic guidelines. Previous studies have revealed that the rigidity of frame connections affects the behavior of the infill frames, but this matter is not considered in the macro modeling of the infill panels. Further, use of the same equivalent struts in the multi-bay infilled frame is questionable, while, the previous researches have suggested that the strength and stiffness of double-bay infill panels are not twice as large as those of a single-bay one. Here, an experimental program has been conducted to explore the effect of connection rigidity and number of bays on the behavior of infilled steel frames. Five specimens including one bare frame, two infilled rigid connection frames, and two infilled pinned connection frames were tested under in-plane lateral loading excitation. Considering the results of experimental tests, a series of parametric analyses have been conducted on the finite element models. The results indicated that the strength and stiffness of the infill panel in the pinned connection frames were less than those in the rigid connection frames. Therefore, a new equivalent strut model was proposed to model the infills in the pinned connection frames. In addition, it was observed that the influence of infill panels in the multi-bay infill frames had a direct relationship with the number of bays. In other words, the properties of equivalent struts do not vary with the increase in the bay numbers in the infilled frames.