锈蚀高铁简支箱梁抗弯性能试验研究

Experimental study on flexural behavior of corroded high-speed railway box girder

预应力混凝土简支箱梁广泛运用于我国高速铁路桥梁建设。在侵蚀环境长期作用下,梁体预应力筋会因锈蚀而导致其性能劣化,进而影响梁的抗弯性能。为研究锈蚀高铁简支箱梁的抗弯性能,现制作了5片T型缩尺模型梁,其中4片梁进行通电加速锈蚀,然后依次对每片梁进行三分点静载试验。试验研究表明:预应力筋锈蚀率超过10%以后,试验梁抗弯性能随预应力筋锈蚀劣化趋势明显;锈蚀率为13.53%时,开裂弯矩与极限弯矩分别下降21.6%和30.7%,极限挠度仅为未锈蚀梁的32.5%,梁脆性破坏特征明显。通过考虑锈蚀预应力筋坑蚀引起的力学性能退化与有效截面面积减小,提出了锈蚀预应力梁剩余抗弯承载力计算经验公式。对比发现,该公式可以较好地预测锈蚀预应力梁的抗弯承载力。

Prestressed concrete simply supported box girder is widely used in the construction of high-speed railway bridges in China.Under the long-term harsh environment,the performance of the prestressed strands of beams will deteriorate due to corrosion,which in turn leads to the decline of the beams’flexural performance.In order to investigate the flexural performance of the corroded high-speed rail simply supported box girder,five T-shaped reduced-scale model beams have been made,four of which were energized to accelerate corrosion,and then each beam was subjected to a threepoint static load test in turn.Experimental research shows that the flexural performance of the test beams deteriorates with the increase of prestressed tendon corrosion when the corrosion rate of prestressed strands exceeds 10%.When the corrosion rate is 13.53%,the cracking moment and the ultimate bending moment are reduced by 21.6%and 30.7%,respectively,meanwhile,the ultimate deflection is only 32.5%of the uncorroded beam,all of which typify the brittle feature of the corroded beams.By considering the degradation of mechanical properties and the reduction of effective cross-sectional area caused by pitting of corroded prestressed strands,an empirical formula for calculating the residual flexural capacity of corroded prestressed beams is proposed.By comparison,it is found that this formula can predict the flexural capacity of corroded prestressed beams well.