不同轴压比下聚丙烯纤维增强混凝土墩抗震性能试验研究

Experimental Study on Seismic Performance of Polypropylene Fiber Reinforced Concrete Piers with Different Axial Load Ratios

为研究塑性铰区采用聚丙烯纤维混凝土(PP-ECC)桥墩的抗震性能,在不同轴压比(n=0.1、0.3)下对4个局部采用PP-ECC桥墩的试件进行低周反复荷载试验,分析桥墩试件的试验轴压比和PP-ECC区高度等设计参数对滞回特性、强度衰减、刚度退化、位移延性及滞回耗能等抗震性能的影响。结果表明:4个试件的破坏过程和破坏形态相似,最终破坏时纵向钢筋受压屈曲,PP-ECC保护层未剥落,核心PP-ECC保持良好;轴压比越大,强度衰减越快,刚度退化越严重,试件整体稳定性越差;PP-ECC桥墩的位移延性和极限位移转角随着轴压比的增加而降低,轴压比越小的试件变形能力越强;随着轴压比的增加,试件的耗能能力、承载能力和初始刚度都有一定的提高。

To evaluate the seismic performance of piers with polypropylene-engineered cementitious composite(PP-ECC) in the plastic hinge region, four PP-ECC piers with axial compression ratio of 0.1 and 0.3 were tested under low-cycle repeated loading. Then the impact of design parameters such as test axial compression ratio and PP-ECC zone height on hysteretic characteristics, strength attenuation, stiffness degradation, displacement ductility, hysteretic energy dissipation and other seismic performance was analyzed. The experimental results show that the failure process and modes of the four specimens are similar. During the ultimate failure phrase, the longitudinal reinforcement yields. However, the PP-ECC cover does not peel off, and the core PP-ECC still maintains in good working condition. The strength attenuation grows faster with the increase of the axial compression ratio. Greater axial compression ratio causes severe stiffness degradation and worse stability of the specimen. The displacement ductility and ultimate displacement angle decrease with the increase of axial compression ratio. The specimens with lower axial compression ratio have stronger deformability. The energy dissipation capacity, bearing capacity and initial stiffness of the specimens improve with the increase of axial compression ratio.