复合配筋混凝土预制方桩轴向抗压性能研究

研发了复合配筋混凝土预制方桩,通过对3种常用桩型方桩试件的足尺轴向抗压性能试验和数值模拟分析,研究复合配筋混凝土预制方桩的裂缝分布、轴压承载力及破坏特征。结果表明:方桩试件存在两种破坏模式,一种为局部破坏,钢筋未压曲,桩端混凝土发生劈裂破坏;另一种为全截面破坏,纵筋向外压曲,箍筋拉断,混凝土压碎而破坏。数值模拟得到的桩身极限抗压承载力与全截面破坏试件的试验结果吻合较好,相差在10%以内,比局部破坏试件的试验结果大约25%。当前设计规范中桩身极限抗压承载力经验公式计算结果相互间差异较大,《混凝土结构设计规范》(GB 50010—2010)的经验公式计算值与数值模拟结果较为接近,且具有一定的安全余度。

Study on axial compression behavior of composite reinforcement concrete prefabricated square piles

The composite reinforcement concrete prefabricated square piles were developed.Full-scale experiment and numerical simulation of axial compression behavior for square pile specimens in three kinds of commonly-used pile types were carried out to investigate the crack distribution,axial compressive bearing capacity and damage characteristic of composite reinforcement concrete prefabricated square piles.The results show that there are two types of failure modes for square pile specimens;one is the partial failure of cross-section,in which the longitudinal reinforcement is not buckled,and the concrete at the pile ends produces the splitting failure;the other is the full-section failure,in which the longitudinal reinforcement is buckled outward,the stirrup is fractured,and the concrete is crushed.The numerical results of the ultimate compressive bearing capacity are in good agreement with the experimental results for full-section failure specimens,and the difference between them is less than 10%.While the numerical results are approximately 25% more than the experimental results for the partial failure specimens.There are great differences among the calculation results of empirical formulas for ultimate compressive bearing capacity of square piles in current design codes,while the calculated value of the empirical formula in the Code for design of concrete structures( GB 50010-2010) is comparatively close to the numerical result,and has enough safety margin.