三层足尺分层装配支撑钢框架结构的振动台试验研究

Full-scale shaking table test of a three-story floor-by-floor assembled steel braced frame

为探究分层装配支撑钢框架体系在真实地震动力作用下的响应与性能,以某3层足尺房屋钢框架结构为研究对象,输入不同水准下的3条地震波进行振动台试验,分析了结构动力分步损伤行为、主（余）震层间变形、残余位移响应及其柔性支撑的可修复性。研究结果表明,结构满足我国规范对于抗震安全性的要求。在罕遇地震作用下,结构损伤集中于柔性支撑而主框架基本保持弹性,表现出损伤控制的特征,且震后基本无残余位移。未对支撑进行修复的结构在余震作用下的位移响应有所放大,但对支撑进行简易修复之后,结构抗震性能基本完全恢复。在超大地震作用下,主框架作为第二道抗震防线发展局部塑性变形,但震后残余位移仍然很小。柔性支撑初始是否张紧对结构初始刚度和层间位移分布有较大影响。支撑在动力作用下的突然张紧对结构产生了冲击效应,而支撑的延性可有效缓解此效应的影响。研究总体表明分层装配支撑钢框架体系应用于低多层建筑时具有优良的抗震性能与震后可恢复性。

For investigating the seismic performance of floor-by-floor assembled steel braced frame, full-scale shaking table tests were conducted on a three-story steel frame structural model using three ground motions in different seismic hazard levels. The structural dynamic stepwise damage behavior, inter-story drift distribution, residual displacement response and the resilience of the tension-only braces were analyzed. The test results show that the seismic performance of the tested structure meets the requirement of current design code. Under the maximum considered earthquake, the damage is concentrated in the braces while the main frame remains elastic which demonstrates damage-control behavior. The residual displacement is near zero in this situation. Under the aftershock at the same intensity level, the inter-story drift response of the damaged structure is enlarged because of the slackness of the tension-only braces. The seismic performance is restored after the braces are retightened. Under extremely strong earthquake, the main frame undergoes local plastic deformation acting as the second seismic defense. The residual inter-story drift is still very small. Whether the tension-only braces are tensioned has a great influence on the initial stiffness of the structure and the inter-story drift distribution. Dynamic impact is induced by the sudden tension of the braces and its effect is effectively controlled because of the high ductility of the braces, In conclusion, the tension-only concentrically braced beam-through frame demonstrates outstanding seismic performance and post-earthquake resilience when applying to low-to-medium rise buildings.