五层梁柱式胶合木结构振动台试验研究

Shaking table test on a five-story post-and-beam glulam structure

为研究多层胶合木结构的抗震性能,设计制作了一个1:2缩尺的五层梁柱式胶合木结构模型,并对增设屈曲约束支撑和木支撑前后的结构模型开展了振动台试验。试验结果表明:纯框架模型抗侧刚度过低,在7度多遇地震作用下纵、横向的最大层间位移角分别达到1/145和1/175,不宜在地震区采用;增设支撑后,模型的基频大幅提高、位移响应显著降低,在7度多遇、基本和罕遇地震作用下的层间位移均满足《多高层木结构建筑技术标准》(GB/T 51226—2017)中弹性和弹塑性位移角限值要求;增设木支撑的横向框架在8度罕遇地震作用下,绝大多数木支撑发生断裂破坏,最大层间位移角达到1/11,但结构并未发生倒塌且梁、柱及节点无明显损伤;增设屈曲约束支撑的纵向框架在8度罕遇地震作用下主体结构无明显损伤,仅在支撑连接板处出现了少量局部的平面外屈曲。屈曲约束支撑和木支撑起到了第一道抗震防线的作用,有效保证了胶合木结构主体框架的安全;在合理设计的基础上,梁柱-木支撑和梁柱-屈曲约束支撑的梁柱式胶合木结构体系均可满足8度区抗震设防要求。

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.