地震作用下斜交简支梁桥旋转机理及斜度影响研究

Study of Rotation Mechanism and Skew Degree Influence of Skewed Simply-Supported Beam Bridge Under Earthquake Excitation

为研究地震作用下斜交简支梁桥梁体转动的影响因素，利用OpenSees软件建立考虑碰撞效应的单跨斜交简支梁桥简化动力计算模型，采用模态分析法和时程分析法计算了斜交简支梁桥的动力特性以及非线性地震响应，分析了梁体旋转发生的机理以及斜度对梁体旋转反应的影响。结果表明：对于橡胶支座支承的斜交简支梁桥，当梁体与边界不发生碰撞时，地震作用下梁体的转动由旋转振型引起，最大转角随斜度的增大而增大；当梁体与边界发生碰撞时，碰撞产生的力矩是引起梁体旋转的主要因素，最大转角随斜度的增大呈先增大后减小的变化规律。横向挡块对斜交简支梁桥梁体旋转具有重要影响，忽略其作用最大转角将被高估22．9％～65．0％。

To study the factors having influences on the beam rotation of the skewed simply- supported beam bridge under earthquake excitation, the software OpenSees was used to create the simplified dynamic calculation model considering the pounding effect for the single-span skewed simply-supported beam bridge. By the modal analysis and the time-history analysis methods, the dynamic characteristics and nonlinear seismic responses o{ the bridge were calculated and the occurrence mechanism of the beam rotation and the influence of the skew degree on the beam rotation responses were analyzed. The results of the calculation and analysis indicate that for the skewed simply-supported beam bridge supported on the rubber bearings, when the beam of the bridge does not pound the boundary, the beam rotation under earthquake excitation is caused by the rotation vibration mode and the maximum rotation angle will increase with the increase of the skew degree. When the beam pounds the boundary, the moment produced by the pounding is the primary factor causing the beam rotation and the maximum rotation angle presents the changing law of increasing first and decreasing then with the increase of the skew degree. The transverse retainers have important influences on the beam rotation of the bridge and if the influences of the retainers are ignored, the maximum rotation angle will be overestimated 22.9%-65.0%.