在役PC梁桥现存应力测试与研究

针对目前预应力梁桥因多方面因素造成的预应力损失,基于静力平衡原理,通过横张增量法对实桥进行预应力测试,采用线性条件下二级间增量方式消除误差,得出实测桥梁的目标钢束现存预应力,并与规范中理论计算值进行对比分析,确定桥梁现存预应力储备状况。研究表明:实测箱梁跨中8根正弯矩束中,有3根钢束预应力实测值小于理论值19.66%～29.25%,墩顶4根负弯矩束实测值较理论值大9.64%～25.14%;由此说明PC箱梁预应力损失较严重,主梁刚度有所下降,结构受力不利;此检测方法及结论可为该类桥梁现存预应力测试评定及病害处置提供参考依据。

Detectionand Research of Existing Stess of PC Grider Bridge in Service

Due to several factors caused prestress loss on present PC bridges,based on the principle of static equilibrium,real bridge prestress is detected by horizontal tension-increment method,with error eliminated by intersecondary incremental way on linear condition.The real bridge value of target steel stands existing prestress is worked out,compared with standard theoretical value.As study shows,among 8 positive moment beams in the measured box girder,there are 3 beams prestess value less than theoretical value of 19.66%~29.25%,the measured value of 4 negative moment beams at pier top is bigger than theoretical value of 9.64%~25.14%;it shows that prestress loss of PC grider bridge is more serious,the girder stiffness is declined,which is adverse for the structure.This detection method and conclusion provide a reference for evaluation and solution of this sort of existing prestressed bridge.