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针对连续变截面桥墩,应用能量法推导了失稳特征值的通用计算公式。应用有限元软件SAP2000,对一座5跨预应力连续刚构桥进行了全过程特征值稳定性分析。分析表明,3#墩最大悬臂施工状态失稳特征值最小,为桥梁的最危险状态。针对3#墩,应用通用公式计算了各个施工工况的失稳特征值,并与数值模拟值进行对比。结果显示,理论计算结果约为数值模拟计算结果的1.7倍,主要是由于连续变截面桥墩的刚度沿墩高变化较大,失稳时的变形不宜采用一阶正弦曲线模拟,但高阶项的引入,导致计算难以实现。因此建议在工程应用中,可由能量法初步估算其稳定性,完成截面初选,在桥梁的施工图设计阶段,采用数值模拟的方法进一步验算其稳定性。
For the continuous variable cross-section piers, the general formula of the instability eigenvalues is deduced by energy method. The finite element software SAP2000 is used to analyze the eigenvalue stability of a 5-span prestressed continuous rigid frame bridge. The analysis shows that the characteristic value of the maximum cantilever construction instability of No.3 Pier is the smallest, which is the most dangerous condition of the bridge. According to the 3 # pier, the instability characteristics of each construction condition are calculated by general formula and compared with the numerical simulation value. The results show that the theoretical calculation is about 1.7 times as much as the numerical simulation. This is mainly due to the fact that the rigidity of pier with continuous variable cross section varies greatly along the pier height, and the first-order sinusoidal simulation is not suitable for the deformation under instability. However, The introduction led to computations difficult to achieve. Therefore, it is suggested that in the engineering application, the stability can be estimated initially by the energy method and the primary section selection is completed. The stability of the bridge is verified by numerical simulation in the design stage of the bridge construction.