Shaking table test of a steel frame with replaceable curved knee braces

In order to realize the rapid post-earthquake repair of steel frame structures, a moment-resisting frame with replaceable curved knee braces and high strength steel components was proposed. Under the target earthquake, the plastic deformation of the structure is concentrated on the curved knee braces, and the high-strength steel components remain essentially elastic to reduce the post-earthquake residual deformation. After the earthquake, the structure can be quickly repaired by replacing the curved knee braces. In order to investigate the seismic performance of the proposed structure and the practicability of replacing the curved knee braces, a 1 / 2 scale test model with concrete floor slabs was designed for shaking table test. The test results show that the test model realizes the predetermined damage control mechanism and can meet the maximum inter-story drift ratio requirements in GB 50011—2010 ‘Code for seismic design of buildings’. As the test model can maintain a large post-yield stiffness under the earthquakes exceeding the rare level, the residual inter-story drift is very small(less than 0. 028%), and the curved knee braces are readily replaced. After replacing the curved knee braces, the test model is repaired to a certain extent, but the stiffness of test model is not fully restored because of the cracking of concrete floor slabs. Under repeated strong earthquakes, the maximum inter-story drift ratio of the test model does not change significantly. Curved knee braces dissipate energy stably, but the maximum deformation of some curved knee braces increases, and the damage shows an uneven development trend in various parts of the test model. © 2022 Science Press. All rights reserved.