Shaking table test on a five-story post-and-beam glulam structure
Xu Qingfeng1,2 Zhang Fuwen1,2 Ma Yurong3 Chen Xi1,2 Dong Jinzhi1,2
1. Shanghai Research Institute of Building Sciences, Shanghai 200032, China;
2. Shanghai Key Laboratory of Engineering Structure Safety, Shanghai 200032, China; 3. Tongji University, Shanghai 200092, China
A half scaled model of a five-story post-and-beam glulam structure was designed and manufactured to study the seismic behavior of multi-story timber buildings. Shaking table tests were conducted on the post-and-beam glulam structural model with and without buckling-restrained braces (BRBs) and timber braces, respectively. Test results showed that the lateral stiffness of the post-and-beam glulam structure without braces was quite low. Under the frequent earthquake with seismic intensity of 7 degree, the maximum inter-story drifts reached 1/145 and 1/175 in the longitudinal and transverse directions respectively, which indicated that the post-and-beam glulam structure without braces was not suitable in seismic regions. After installing the braces, the fundamental frequency of test model was greatly improved and the displacement response was reduced significantly. The inter-story drifts under the frequent, basic and rare earthquakes with seismic intensity of 7 degree can meet the requirements of the elastic and elastic-plastic limits in Technical standard for multi-story and high rise timber buildings (GB/T 51226—2017). Most of the timber braces fractured under the rare earthquake with seismic intensity of 8 degree in the transverse direction, and the maximum inter-story drift reached 1/11. However, the model did not collapse, and no obvious damage was observed in the beams, columns and joints. After installing the buckling-restrained braces, no significant damage occurred under the rare earthquake with seismic intensity of 8 degree in the longitudinal direction. Only local out-of-plane buckling appeared in the connecting plate of the BRBs. As the first seismic fortification line, the BRBs and timber braces effectively ensure the safety of the post-and-beam glulam structure. With reasonable design, the post-and-beam glulam structures with timber braces or BRBs can meet the requirements for seismic resistance in the regions with seismic fortification of 8 degree.