薄壁高墩连续刚构桥的稳定分析

摘要

利用 Midas civil 有限元软件，对杨家湾大桥15＃薄壁墩最高裸墩、最大悬臂阶段和成桥3种状态进行了稳定分析，给出了结构的失稳模态和荷载—位移曲线，得到了各工况下的屈曲荷载和稳定安全系数。最高裸墩、最大悬臂和成桥3状态下，最大悬臂状态的稳定值最小，第一阶特征值为15.67，最大悬臂状态为稳定控制的最不利阶段。考虑几何非线性影响时，最不利工况下各阶稳定值下降，墩底轴力和墩顶位移增大，荷载与位移呈非线性变化，特别是在最大悬臂状态变化更加明显。高墩大跨连续刚构桥梁的稳定性主要跟施工节段有关，施工时的风荷载、温度荷载对结构的稳定影响小，但挂篮跌落对结构稳定性的影响大；施工过程中一定要加强管理，防止挂篮意外跌落，避免出现梁段重量不均或者加载不均匀，确保施工安全。%By utilizing the finite element software Midascivil,the stability of the highestbare pier, the stability of the longest cantilever during construction and the stability in complete stage of the Yang Jia Wan bridge 15 #pier are analyzed,the buckling modeand the load-displacement curve are obtained, the buckling load and the stabilitysafety factor ofall conditions aredrown.In the three conditions of the highest bare pier,the longest cantilever and thecompleted bridge,the value of stability is lowest in the state of the highest bare pier,and the eigenvalue is 15.67 in the first stage.The state of the longest canti-lever is the most unfavorable stage for stability control.When considering the geometric nonlinearity,in the most unfavorable conditions,the value of stability in each stage would decrease,and the axial force on the bottom of pier and the displacement on the top of pier would increase,and the load and displacement act as nonlinear changes,especially in the longest cantilever state.The stability of the high-pier and long-span continuous rigid frame bridge is mainly related with construction segments.The wind load and tem-perature load have low influences on structure stability.However,the dropping hanging baskets have a great impact on structure stability.Therefore,management should be strengthened to prevent the falling hanging baskets during the process of construction.And in order to ensure the construction safety,uneven weight of beams or uneven loads also should be avoided.