In this paper, the verticalseismic effects on tunnels are studied based on a classic mass–damper–spring model. An analyticaldiscrete modelof urban underground tunnels subjected to verticalearthquake excitations is p...In this paper, the verticalseismic effects on tunnels are studied based on a classic mass–damper–spring model. An analyticaldiscrete modelof urban underground tunnels subjected to verticalearthquake excitations is proposed by considering the first verticalvibration mode. Taking a light railproject in Tianjin as an example, this study uses the proposed discrete modelto analyze the displacements of tunneland soilunder verticalearthquake excitations. The soildisplacement responses at different tunnellocations are analyzed with linear random vibration theory.The computationalcost is greatly reduced using the proposed model. It can be seen that different from the case of horizontalearthquakes, the displacement responses under verticalearthquake excitations keep growing after seismic acceleration reaches its peak for a short duration, and then,they begin to decay. The soils at different positions around the tunnels have large relative displacement under verticalearthquake excitations. Moreover, a finite-element modelis also established for displacement responses using ABAQUS.The comparison with the results of the finite-element modelshows that the results of the proposed discrete modelare available.展开更多
针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的...针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的恢复力计算公式,进行拟静力试验,设计装置在隔震桥梁中的布置方式,给出了在SAP2000中实现RMFD装置恢复力模型的方法,利用MATLAB和SAP2000对同一单自由度结构的响应进行对比,验证了方法的有效性。进而以某一6跨连续摩擦摆隔震桥梁为研究对象,利用SAP2000软件对比分析大震下非隔震桥梁、摩擦摆隔震桥梁以及RMFD限位摩擦摆隔震桥梁的地震响应、减震率、支座位移控制效果,以及等效摩擦力变化时墩柱响应峰值、减震率及墩柱损伤状态的变化情况。结果表明:RMFD作为桥梁隔震限位装置,仅需要较小的螺栓预紧力即可获得较大的RMFD阻尼器出力,位移行程大、耗能能力强,能够有效地将隔震层的位移控制在允许范围之内,避免支座位移超限引起的落梁、碰撞等震害的发生;同时,桥墩的墩底剪力、墩顶位移等地震反应稍有增大,减震率有所降低,但降幅均在10%以内,隔震桥梁仍具有良好的减震效果;随着等效摩擦力的增大,墩顶位移、墩底剪力、墩底弯矩最大值均不断增大,但支座的位移逐渐减小,说明螺栓预紧力越大,隔震层的位移控制效果越好,但其余地震响应的控制效果变差,桥墩损坏程度会加大,因此应合理设计预紧力的大小以取得理想的减震效果。展开更多
基金supported by the National Natural Science Foundation of China (No. 51478311)the Natural Science Foundation of Tianjin, China (No. 14JCQNJC07400)
文摘In this paper, the verticalseismic effects on tunnels are studied based on a classic mass–damper–spring model. An analyticaldiscrete modelof urban underground tunnels subjected to verticalearthquake excitations is proposed by considering the first verticalvibration mode. Taking a light railproject in Tianjin as an example, this study uses the proposed discrete modelto analyze the displacements of tunneland soilunder verticalearthquake excitations. The soildisplacement responses at different tunnellocations are analyzed with linear random vibration theory.The computationalcost is greatly reduced using the proposed model. It can be seen that different from the case of horizontalearthquakes, the displacement responses under verticalearthquake excitations keep growing after seismic acceleration reaches its peak for a short duration, and then,they begin to decay. The soils at different positions around the tunnels have large relative displacement under verticalearthquake excitations. Moreover, a finite-element modelis also established for displacement responses using ABAQUS.The comparison with the results of the finite-element modelshows that the results of the proposed discrete modelare available.
文摘针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的恢复力计算公式,进行拟静力试验,设计装置在隔震桥梁中的布置方式,给出了在SAP2000中实现RMFD装置恢复力模型的方法,利用MATLAB和SAP2000对同一单自由度结构的响应进行对比,验证了方法的有效性。进而以某一6跨连续摩擦摆隔震桥梁为研究对象,利用SAP2000软件对比分析大震下非隔震桥梁、摩擦摆隔震桥梁以及RMFD限位摩擦摆隔震桥梁的地震响应、减震率、支座位移控制效果,以及等效摩擦力变化时墩柱响应峰值、减震率及墩柱损伤状态的变化情况。结果表明:RMFD作为桥梁隔震限位装置,仅需要较小的螺栓预紧力即可获得较大的RMFD阻尼器出力,位移行程大、耗能能力强,能够有效地将隔震层的位移控制在允许范围之内,避免支座位移超限引起的落梁、碰撞等震害的发生;同时,桥墩的墩底剪力、墩顶位移等地震反应稍有增大,减震率有所降低,但降幅均在10%以内,隔震桥梁仍具有良好的减震效果;随着等效摩擦力的增大,墩顶位移、墩底剪力、墩底弯矩最大值均不断增大,但支座的位移逐渐减小,说明螺栓预紧力越大,隔震层的位移控制效果越好,但其余地震响应的控制效果变差,桥墩损坏程度会加大,因此应合理设计预紧力的大小以取得理想的减震效果。
