预应力混凝土空心方桩承台节点抗震性能试验研究

Quasi-static Tests of Pile-cap Connections for the Prestressed Spun Concrete Square Piles

对预应力混凝土空心方桩-承台节点进行了6组足尺试件的拟静力试验,分别讨论轴压力、桩身配筋量、桩头嵌固深度和加载方向等4个因素对节点抗震性能的影响。研究表明:对于HKFZ400(210)桩型,在1 700kN及以上的轴压作用下,主要的破坏模式为近节点区桩身压弯破坏,破坏性质均为小偏心破坏;轴向荷载使得预应力混凝土空心方桩承台节点极限抗弯承载力增强,却削弱其变形能力,在1 700kN轴压作用下节点表现出了较好的变形能力;对角线加载方向是构件的静力弱方向,其极限承载力略低于正截面加载,但却有更大的变形能力;在50mm嵌固深度条件下,节点区没有发生锚固失效,反而表现出了更大的变形能力,但在破坏状态下的等效粘滞阻尼系数有所降低。

Quasi-static tests of six full-scale prestressed spun concrete square piles-cap connections were conducted to investigate the influence of 4 parameters on the seismic behavior of the connection.The results and findings indicate：①With axial load larger than 1 700 kN,failures governed by concrete compression take place in the connected part of the piles due to small eccentricity.②Axial load increases the loading capacity for the connection but on the other hand decreases its deformation capacity.The connection shows considerable deformation capacity under axial load of 1 700 kN.③Connection under diagonal loading condition is statically weaker,while showing better deformation capacity.④With a 50 mm dowel depth into the cap,the connection functions well and is capable of larger deformation.But the corresponding equivalent viscous damping coefficient is lower at failure.