九度地震区高铁组合减隔震体系桥梁振动台试验研究

Shaking table test on high speed railway bridge using combined seismic isolation system in nine-degree seismic regions

为研究一种组合减隔震体系在九度地震区高铁简支梁桥中的可行性及适应性,以某九度强震区高铁典型32 m简支箱梁为原型,开展了1∶10缩尺模型的3跨简支梁全桥振动台试验。采用15组近断层地震波按多遇、设计、罕遇地震强度进行纵向+竖向、横向+竖向联合输入,采集试验过程中桥梁关键构件地震位移、加速度、钢筋应变等响应数据,观测各地震输入工况后桥梁损伤情况,综合分析试验现象和实测数据。结果表明:采用双曲面减隔震支座+榫形金属减震限位装置+钢防落梁组合减隔震体系后,多遇地震下,桥墩保持弹性状态,墩梁相对位移较小,主梁横向和竖向加速度分别控制在0.3 g和0.5 g以内,保障了行车安全;设计地震作用下,组合减隔震体系发挥了良好的减隔震效果,耗散了地震能量,墩梁相对位移控制在20 mm以下,桥墩发生轻微损伤,其位移延性比小于1.2;罕遇地震作用下,组合减隔震体系稳定工作,保证了主梁不发生落梁震害和跳梁风险,桥墩发生中等损伤,其位移延性比控制在2.2以下,没有倒塌风险。组合减隔震体系实现了9度地震区高铁32 m跨简支箱梁各项抗震性能目标,可为今后9度地震区高铁简支梁桥减隔震设计提供试验依据。

To investigate feasibility and applicability of high-speed railway simply supported beam with a combined seismic isolation system in nine-degree seismic regions,taking the type high-speed railway 32 m simply supported beam as a prototype,and the shaking table tests of a 1/10 scale 3 span bridge model were conducted.Fifteen typical near-field ground motion records were selected as the input excitations,and the vertical+vertical and horizontal+vertical were combined input.The seismic displacement,acceleration,reinforcement strain and other response data of key components of the bridge were collected during the test,the damage of the bridge after each earthquake input condition were observed,and the experimental phenomena and measured data were analyzed comprehensively.The results show that the pier remains elastic under earthquakes,and the relative displacement of pier and beam becomes smaller,the transverse and vertical acceleration of the main beam is controlled within 0.3 g and 0.5 g,respectively,which ensures the driving safety after the bridge adopts the hyperboloid bearing+metal damping limit device+steel anti-falling beam combined damping.The combined seismic isolation system has played a good effect of damping and isolation under the designed seismic action,and dissipated earthquake energy.The relative displacement of pier and beam is controlled below 20 mm,the pier is slight damage,and its displacement ductility ratio is less than 1.2.The combined seismic isolation system works stably to ensure that the main beam does not suffer from falling earthquake and girder hopping risk under the rare action of earthquake,and the pier is moderate damage,and its displacement ductility ratio is controlled below 2.2,without collapse risk.The combined seismic isolation system has achieved the seismic performance targets of 32 m span simply supported beam of high-speed railway in nine-degree seismic regions.