应力等效法在单梁静载试验中的应用研究

单梁静载试验荷载的确定通常以控制弯矩的加载效率为控制目标,常规做法为“弯矩等效法”,然而单梁实际受力特性与成桥受力状态的不符合使得试验荷载计算值失真.为解决上述问题,提出一种更符合实际的“应力等效法”.通过采用MIDAS/Civil有限元软件对不同跨径的预制箱梁受力状态进行计算,并对“应力等效法”与“弯矩等效法”的计算结果进行对比分析.结果表明:以“应力等效法”,即叠加应力或以叠加应力反算出来的弯矩作为静载试验中的控制指标更接近于结构的实际受力状态.与直接采用“弯矩等效法”计算的弯矩作为控制内力的计算方式比较,“应力等效法”比其少12%左右,可减少荷载试验的误判,对类似桥梁的单梁荷载试验具有一定的指导意义.

Research on application of stress equivalent method in single beam static load test

The determination of static test load of single beam usually takes the loading efficiency of control bending moment as the control objective, and the conventional method is “moment equivalent method”. However, the actual stress characteristics of single beam do not conform to the stress state of the completed bridge, which makes the calculation value of test load distorted. In order to solve the above problem, this paper proposes a more practical “stress equivalence method”. By using MIDAS/Civil finite element software, the stress state of precast box girder with different spans is calculated, and the calculation results of “stress equivalent method” and “moment equivalent method” are compared and analyzed. The results shows that the “stress equivalent method”, that is, the superimposed stress or the bending moment calculated by the inverse superposition stress as the control index in the static load test, is closer to the actual stress state of the structure. Compared with the bending moment calculated by the “moment equivalent method” as the calculation method of controlling internal force, the “stress equivalent method” is about 12% less, which can reduce the misjudgment of load test, and has certain guiding significance for the load test of single beam of similar bridges.