基于横张增量法的PC梁桥现存应力测试与评估

Detection and assessment on existing stress of PC girder bridge based on horizontal tension-increment method

针对目前预应力混凝土桥梁由于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张力测试,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应力,并与规范中理论设计值进行对比分析,确定在役桥梁预应力储备状况。研究结果表明:实测箱梁跨中8根正弯矩束中,有3根钢束有效预应力实测值小于设计值13.36%～23.7%,墩顶4根负弯矩束实测值较设计值大16.86%～24.59%,由此说明,PC箱梁预应力损失较严重,主梁刚度有所下降。

Aimed at the prestress loss on present prestressed concrete bridges,based on the principle of static equilibrium,a real bridge pre-tension was detected by horizontal tension-increment method,the intersecondary incremental way on linear condition was used to eliminate the errors.The existing stress value of target steel beam of service bridge was worked out and compared with the standard theoretical value.The results show that the effective prestress values of 3 beams among 8 positive moment beams in the measured box girder are less than the theoretical values from 13.36% to 23.7%,the measured values of 4 negative moment beams at pier top are bigger than the theoretical values from 16.86% to 24.59%,that indicates the prestress loss of PC girder bridge is more serious,the girder stiffness is declined.6 tabs,2 figs,9 refs.