In-plane shake table testing of gravity load designed reinforced concrete frames with unreinforced masonry infill walls

A large number of existing buildings, particularly those constructed prior to the enforcement of ductile design philosophy of 1970’s, were primarily designed and detailed to resist gravity loads. Structures of this type do not have the current reinforcement detailing required by modern codes in high and medium seismic zones and, hence, they are considered potential life–safety hazards. In addition, the presence of masonry infill walls was often ignored by engineers since they are normally considered as architectural elements. However, lessons learned from past earthquakes and from several tests performed have shown that those walls tend to interact with the bounding frame when the structural system is subjected to moderate or severe earthquake ground motions and that such interaction may or may not be beneficial to the performance of the structure. This paper presents the first part of an experimental testing program carried out at the University of British Columbia (UBC) in Vancouver, Canada testing the performance of 1/2 scale Gravity Load Designed Reinforced Concrete (GLDRC) frames with Unreinforced Masonry Walls. The first part of this testing program consisted of one monotonic loading test on an Infilled frame and two series of shake table tests, one on an Infilled frame and one on a Bare frame with the UBC Earthquake Engineering Research Facility (EERF) unidirectional shake table.