采用UHPC连接的预制拼装桥墩构造及试验研究

Technical and experimental studies of precast bridge piers with the UHPC connection

该文以采用UHPC新型连接构造的预制拼装桥墩为背景,设计制作了一高一矮2个桥墩模型,并采用拟静力试验方法研究了模型的破坏模式、滞回特性、骨架曲线和耗能能力,比较、分析了UHPC连接高墩和矮墩的损伤情况、破坏特点和变形机理。试验结果表明,采用UHPC连接的预制拼装桥墩具有较好的耗能能力,桥墩墩底连接段未发生破坏,连接可靠。对比两个模型的试验结果可知,高墩模型具有较好的位移承载能力和较小的残余变形,模型的破坏模式为墩身标准段(非连接段)普通混凝土压溃的弯曲破坏。而矮墩模型的极限承载力更大,且矮墩受剪力影响明显,破坏模式为墩身斜裂缝发展以及墩底与承台接缝处张开,水平承载能力下降到峰值承载力的80%。基于两个模型的破坏模式,文章还分析了2个模型的变形机理,给出了相应的抗震设计建议。

To investigate the seismic performance of the precast bridge pier with a novel ultra-high performance concrete(UHPC) connection between precast columns and footings, two test models with different heights were designed and constructed.Quasi-static tests were carried out to investigate the failure modes, hysteretic characteristics, skeleton curves, and energy dissipation capacities of the two models.The damage characteristics and deformation mechanisms of the two models were compared and analyzed.The test results show that the precast bridge piers with the UHPC connection exhibit superior energy dissipation capacity, and no damage was observed around the connecting region of both two models, indicating that the connection with UHPC is reliable.By comparing the test results of the two models, the high pier model has better ultimate displacement capacity with a comparatively smaller residual displacement, and the failure mode is disclosed to be the flexural failure with crushing of core concrete above the connection region.On the other hand, the short pier model exhibits larger load resistance.Due to the shear force, the failure mode of the short pier model appears to be the development of the diagonal cracks in the column and the obvious opening of column-to-footing, and the lateral force of the short pier may drop to 80% of its peak force.Based on the failure modes, the deformation mechanisms of the two models were analyzed and the corresponding seismic design recommendations were given.