碰撞对高铁简支桥梁横向地震响应影响的振动台试验研究

地震所导致的碰撞是影响桥梁结构地震响应的一个重要因素。该文以32 m标准跨径高铁简支梁桥为研究对象，按1/6缩尺比设计及制作了单跨桥梁振动台试验模型，并针对以往点-面接触碰撞测力装置不能真实反映原型结构碰撞接触形式的不足，设计了一种新型面-面接触的碰撞测力装置。通过振动台试验研究了桥梁模型在地震激励下的横向碰撞效应，并通过快速傅里叶变换（FFT）从频域角度分析了碰撞对桥梁结构横向地震响应的影响。结果表明：新型测力装置能够较为准确地测得挡块与垫石之间的碰撞力时程；挡块与垫石间的碰撞限制了墩梁间的横向相对位移的发展，但会放大桥墩墩底弯矩响应和梁体加速度响应。在不考虑挡块时，桥梁结构的地震响应功率谱在低频区（结构基频附近）具有较高的幅值，即地震响应主要受结构基频控制；而在设置挡块后，碰撞改变了地震响应的频率分布，在高频区的功率谱幅值明显增大。

SHAKE-TABLE TESTS ON THE INFLUENCE OF THE POUNDING ON TRANSVERSE SEISMIC RESPONSES OF HIGH-SPEED RAILWAY SIMPLY-SUPPORTED BRIDGES

Earthquake-induced pounding is a critical factor affecting seismic responses of bridges.A high-speed railway simply-supported girder bridge with a standard span of 32 m was studied.A single-span bridge model was designed and manufactured at a scale of 1/6.A new surface-surface contact device for measuring the pounding force was proposed to overcome the shortcoming of previous point-surface devices that cannot model the actual contact form of the structures.A series of shake-table tests were conducted to investigate the transverse pounding effect of the bridge model,and the influence of the pounding on transverse seismic responses of the bridge was analyzed in the frequency domain by the fast Fourier transform(FFT).The results showed that:1)the new force measuring device could accurately measure the time history of the pounding force;2)the pounding between the shear keys and the bearing bases restricted the development of the relative transverse displacement between the superstructure and the substructure,but it amplified the girder acceleration and the bending moment near the base of the pier;3)when the shear keys were not installed,the power spectra of the seismic responses had higher amplitudes in the low-frequency region(near the fundamental frequency of the bridge model),i.e.the seismic responses were dominated by the fundamental frequency of the structure when the pounding was not considered.However,after the shear keys were installed,the pounding altered the frequency content of the seismic responses,and the amplitudes of power spectra were increased significantly in the high-frequency region.