基于能量法的悬索桥主索鞍顶推计算方法

Calculation Method of Saddle Pushing of Suspension Bridge Based on Energy Method

为了确保悬索桥的主塔在加劲梁吊装过程中始终处于安全受力状态,合理确定主索鞍顶推量和顶推阶段至关重要.基于能量原理,应用Rayleigh-Ritz法推导了主塔最大容许偏位计算公式.从主塔塔顶偏位和塔底应力2个角度提出优化主索鞍的顶推方法,最后通过有限元法验证近似公式的精度.研究结果表明:推导的公式计算结果与有限元计算结果相差3.4%,考虑P-Δ比不考虑P-Δ效应的塔顶偏位相差为4.6%,主塔的最大容许偏位随着加劲梁的不断吊装而逐渐增大,增幅可以达到19.9%,同时,可增加主索鞍顶推量和顶推时间间隔,减小顶推次数,从而解决悬索桥主索鞍顶推问题,使得主塔受力处于最优状态.

In order to ensure that the main tower is in the safe state during lifting of stiffening girders of suspension bridge, it is essential to determine the pushing values and pushing stages. A formula for the maximum allowable displacement of main tower was derived with Rayleigh-Ritz method based on energy principle. The pushing method of the main cable saddle was optimized from the perspective of both displacement of main tower top and stress at tower bottom. Finally, accuracy of the proposed formula was verified by the finite element method ( FEM ) . The results show that the error between the result from proposed formula and that from FEM is 3. 4%, and the error from processes considering and without considering the effects of P-△ on the main tower is 4. 6%. The maximum allowable displacement of the tower keeps increasing with the lifting of stiffening girders, and the increase amplitude can reach 19. 9%. Meanwhile, the pushing values and time interval should be gradually increased and pushing times should be reduced, which resolves the problem of saddle pushing of suspension bridge and optimizes stress state of the main tower.