整体式桥台-H形钢桩-土体系抗震性能试验

整体桥因其全周期寿命长、整体性好和养护费用低等特点，得到了广泛应用，但对其在地震荷载作用下的受力特点和变形规律还缺乏深入研究。基于此，以某整体桥为背景，制作桥台-H形钢桩试验模型，开展整体式桥台-H形钢桩-土体系抗震性能拟静力试验研究，分析桥台-H形钢桩的破坏模式、滞回性能、骨架曲线、水平变形和桥台转角等变化规律。试验结果表明：H形钢桩出现较大的负向残余变形，但负向加载下H形钢桩未出现破坏；台后、台底及桩顶土体均出现大范围脱空；试件的等效黏滞阻尼比约为0.35，具有良好的耗能能力；正向加载下试件的弹性抗弯刚度是负向的12.6倍，最大承载力是负向的3.85倍，台后土对试件的刚度和承载力影响显著；破坏时试件刚度减小至初始刚度的33%，退化不显著；相比位移延性和割线刚度，采用环线刚度分析其抗震性能更为合适，改进后的割线刚度能更准确地反映试件的刚度退化；考虑整体和局部累积变形的影响，大加载位移作用下，桩身出现较大的负向整体累积变形，且桩身沿深度方向多处出现局部累积变形；加载过程桥台仅发生刚体位移，正向转角逐渐增大，负向转角先增大后减小再转为正向倾斜。研究发现整体式桥台-H形钢桩-土体系拥有优越的抗震性能。

Experimental on Seismic Performance of Integral Abutment-steel H-pile-soil System

The integral abutment jointless bridge (IAJB) has been widely applied in bridge engineering for its advantages such as long service life, good integrity, and low maintenance cost. However, its mechanical characteristics and deformation law under earthquake loads lack thorough investigations. In this study, a practical engineering of IAJB was adopted as a sample, and an abutment-steel H-pile structural model was manufactured to conduct on the seismic performance of integral abutment-steel H-pile-soil system under cycle quasi-static test. Some significant results were obtained, including the failure mode, hysteretic behavior, skeleton curve, horizontal deformation law, and abutment rotation angle law. The results indicate that steel H-pile carries a large negative residual deformation but does not damage under negative loading. Behind and at the bottom of the abutment and at the top of the pile, some large-scale voids are observed. The equivalent damping ratio of the abutment and pile is about 0.35, which indicates a good energy dissipation capacity. Furthermore, the elastic bending stiffness of the specimen under positive loading is 12.6 times that under negative loading, and the maximum bearing capacity is 3.85 times that under negative loading. Additionally, the backfill has a significant influence on the stiffness and bearing capacity of the specimen. After the test, the stiffness of the specimen reduced by 33%, which is relatively unremarkable. Compared to the displacement ductility and secant stiffness, the loop stiffness is more appropriate for analyzing the seismic performance of the specimen, and the improved secant stiffness can more accurately reflect the stiffness degradation of the specimen. Considering the effect of full and local accumulative deformation, under the large displacement load, the steel H-pile appears to have a larger negative, full accumulative deformation, and there are many local accumulative deformations along the depth direction. During the loading process, the abutment only exhibits rigid body displacement, and the positive angle gradually increases. Moreover, the negative angle of abutment increases and decreases before finally turning to the positive angle. These results show that the integral abutment-steel H-pile-soil system exhibits excellent seismic performance.