基于差值法的荷载试验分析研究

Analysis and Study of Load Test Based on Difference Value Method

荷载试验是检验桥梁结构实际承载能力最直接有效的方法,但是在对钢便桥及部分钢桁架桥梁进行试验时发现其挠度实测值往往大于理论值,且应变分布不规律,其原因为该类桥梁构件间连接不紧密且构件可能存在较大的尺寸误差,使结构在承受较小荷载的作用下出现严重下挠和局部不受力状况。为了精确评价该类桥梁的实际承载能力,提出差值荷载试验分析法。荷载试验中每个工况均分多级加载,其中第一级加载能使结构完全进入工作状态。对荷载试验结果进行分析时,每一级试验结果均减去第一级或前一级试验结果,从而消除结构因连接不紧密和尺寸误差引起的大部分误差。再对实测的差值结果与理论的差值结果进行比较分析,从而间接评判该桥的实际承载能力。研究结果表明,差值荷载试验分析法可以有效解决荷载试验无法准确评价钢便桥及部分连接不紧密的钢桁架桥梁承载能力的问题。

The load test is the most direct and efficient method to inspect the actual carrying capacity of bridge structure.But it is found that its defection measured value is often larger than the theoretical value during the test of steel temporary bridges and the partial steel truss bridges,and the strain distribution is irregularite.Its causes are the loose connection among the components of this bridge and the larger dimension error possibly existing in the components,which make the structure have the serious down deflection and partial no-stress state under the function of bearing the smaller load.In order to exactly evaluate the practical carrying capacity of this bridge,the difference value load test analysis method is proposed.Each working condition is all divided into the multistage loading in the load test,in which the first-stage loading can make the structure completely enter the working state.The test result of each stage is all subtracted from the first-stage or the former-stage test result during the analysis of load test result so as to eliminate the most error caused by the loose connection and dimension error of structure.The measured difference value result and the theoretical difference value result are compared and analyzed again so as to indirectly judge the actual carrying capacity of this bridge.The study result shows that the difference value load test analysis method can effectively solve the problem of the load test hard to exactly evaluate the carrying capacities of the steel temporary bridges and some loose connection steel truss bridges.