考虑地震动随机性的隔震曲线连续梁桥动力响应分析

Seismic response analysis of the isolated curved girder bridge considering the randomness of ground motions

隔震曲线梁桥因结构形式的复杂性与独特性,其地震响应相较于隔震直线梁桥更为复杂。为了研究地震动随机性对隔震曲线梁桥动力响应的影响,建立了某三跨隔震曲线梁桥有限元模型,对不同地震动入射角及不同地震动强度下的隔震曲线梁桥进行了非线性时程分析,同时考虑了曲线梁桥圆心角及隔震支座非线性的影响。以典型地震波为例,研究了隔震支座位移、中墩墩底剪力随地震动入射角、地震动强度及曲线梁桥圆心角的变化规律。结果表明:地震动入射角的随机性对隔震曲线梁桥切向及径向的地震响应有显著影响。切向响应与径向响应最大值所对应的最不利入射角相差约90°;相较于中墩支座,边墩支座的位移响应受曲线梁桥圆心角的影响更大;与中墩径向剪力相比,其切向剪力对圆心角的变化更加敏感;相同地震动入射角下,圆心角的增大使得隔震曲线梁桥中墩受力更加不均衡;当地震动沿着最不利入射角输入时,在同一峰值加速度的地震动作用下,不同圆心角的隔震曲线梁桥的动力响应基本一致。

Due to the complexity and uniqueness of the structural type,the seismic response of the isolated curved girder bridge is more complicated than the isolated girder bridge.A finite element model of a three-span isolated curved girder bridge is established to investigate the influence of randomness of ground motions on seismic response.Nonlinear time history analyses are conducted with consideration of different angles of seismic incidence and seismic intensity.The displacement of isolated bearings and shear force of piers of the bridge under the selected ground motions are studied.Results show that the randomness of angle of seismic incidence has a significant effect on tangential and radial seismic responses of the isolated curved girder bridge.The difference value of the critical angles of seismic incidence corresponding to the maximum tangential and radial responses is near to 90 degrees.Compared with the middle bearings,the displacement responses of the side bearings are greatly influenced by center angle.The tangential shear force of the middle pier is more sensitive to the change of the center angle than the radial shear force.The internal force of the middle pier is more unbalanced with the increase of center angle under the same angle of seismic incidence.When ground motion is input along critical angles of seismic incidence,the seismic responses of the isolated curved girder bridge with different central angles are basically same under the same peak acceleration of ground motion.