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为研究场地效应对高墩桥梁随机地震响应的影响规律,基于随机振动理论,研究了不同墩高和墩高差时场地效应对山区高墩桥梁在强地震作用下多点激励随机响应规律。对基于ANSYS的随机振动计算理论进行推导并建立三维数值有限元模型,对不同墩高和墩高差的山区高墩桥梁进行不同场地条件下的多点激励随机地震分析。研究表明:场地效应对高墩桥梁地震响应影响显著。软场地条件下,桥墩位移和主梁轴力均较硬、中场地时大;随着墩高的增加,硬、中、软场地效应对主梁轴力影响先增大后减小;随着墩高差的增加,主梁轴力变化规律性不强,成波动性变化;主梁横桥向弯矩对场地效应敏感,软场地时响应是硬、中场地时的5～12倍,靠近高墩处的边跨反应比矮墩处边跨明显;随着墩高差的增加,软场地对主梁弯矩响应放大作用也随之增加。
In order to study the effect of site effect on random seismic response of high pier bridge, the random response of multi-site excitations to high pier bridge in mountainous area under strong earthquake was studied based on stochastic vibration theory with field effect of different pier height and pier height difference. The theory of stochastic vibration based on ANSYS is deduced and a three-dimensional numerical finite element model is established. Stochastic seismic analysis of multi-point excitations under different site conditions is carried out for high-pier bridges in mountainous areas with different piers height and pier height difference. The research shows that the site effect has a significant influence on the seismic response of high pier. Under the condition of soft ground, the displacements of the pier and the axial force of the main girder are both hard and the midfielder time is large. With the increase of pier height, the influence of the hard, medium and soft ground effect on the axial force of the main girder first increases and then decreases; The variation of pier height, the regularity of the axial force of the main girder is not strong and the variation of the axial force of the main girder is fluctuating. The transverse girder bending moment of the main girder is sensitive to the site effect. When the soft ground response is 5 ~ 12 times of the hard and medium field, The side span response at high pier is more obvious than that at short pier. With the increase of pier height difference, the amplifying effect of soft ground on the bending moment of main girder also increases.