地震波的反应谱谱形对RC梁桥结构非线性地震反应的影响

THE INFLUENCE OF RESPONSE SPECTRAL SHAPE OF EARTHQUAKE GROUND MOTIONS ON NONLINEAR SEISMIC RESPONSES OF REINFORCED CONCRETE GIRDER BRIDGE STRUCTURES

地震经验表明:各类结构的震害主要表现为强震地面运动的幅值、频谱特性和持时这3个基本要素综合影响的结果。为了将频谱与幅值、持时的影响进行解耦,采用实际地震波和匹配同一反应谱的人工波,通过IDA分析,对一座钢筋混凝土连续梁桥进行研究。对比强震地面运动的频谱特性特别是反应谱谱形与结构地震反应的相关性表明:随着地面运动强度的增加以及桥梁结构非线性程度的提高,谱形对结构非线性地震反应的影响日益显著。如果在纵桥向、横桥向存在高模态影响,则高模态效应与谱形的影响会相互耦合,从而进一步增强对于结构非线性地震反应的影响。对于具有不同动力特性的梁桥结构,反应谱不同区段的谱形对于结构非线性地震反应的影响差异显著,并对影响显著的反应谱区段进行了预计。

Earthquake experience has shown that the comprehensive influence of key characteristics of earthquake ground motions, namely amplitude, frequency content, duration, on all kinds of structures accounted for their failure and destruction in an earthquake. The incremental dynamic analysis of a six span reinforced concrete continuous girder bridge using real accelerograms and spectral matched artificial accelerograms is performed for decoupling the influence between frequency content and duration or amplitude on structural seismic responses. The comparison of correlation between frequency content of earthquake ground motions, especially response spectral shapes and nonlinear seismic responses of RC girder bridge structures reveal that the spectral shape has more and more important influence on nonlinear seismic responses with the increase of ground motion intensity measures and the extent of nonlinearity of bridge structures. If there is a higher modal effect in the longitudinal or transverse direction of bridges, the interaction of the higher modal effect and spectral shape can enhance the influence of frequency content on nonlinear seismic responses of bridge structures. Furthermore, spectral shapes in various parts of response spectra have significantly different effects on nonlinearity of responses of bridge structures of different dynamic properties and key parts of response spectra of remarkable effects on nonlinear seismic responses of RC girder bridge structures are predicted.