卡扣式机械连接预应力实心方桩承台节点力学性能有限元分析

Finite Element Analysis of Mechanical Properties of Pile-cap Connections for Prestressed Concrete Solid Pile Using Snap-in Mechanical Connection

介绍了一种新桩型-卡扣式机械连接预应力混凝土实心方桩,然后针对卡扣式机械连接预应力混凝土实心方桩和承台处节点试验中没有考虑的因素进行了数值模拟分析,包括预应力方桩配箍率、增加的普通钢筋配筋率以及不同有效预应力等因素,以探究这些因素对预应力方桩承台节点力学性能的影响。研究结果表明:不同箍筋间距对节点的水平最大承载能力影响较小;箍筋间距越小,对混凝土的约束能力就越大,节点水平承载力的下降段越平缓;箍筋间距越大,水平承载力的下降段越陡峭,刚度退化越快。提高有效预压应力可以提高节点处的水平承载能力;有效预应力越大,桩身会发生更大的损伤,有效预应力越小,承台会发生更大的损伤;增加普通钢筋,能有效改善预应力方桩的延性和水平承载能力;使用大直径钢筋能增加节点的锚固性能,桩身承受更多的损伤。数值模拟成果可为卡扣式机械连接混凝土实心方桩的后期改进和应用推广提供可靠的依据。

First,a new pile type-prestressed concrete solid pile with snap-in mechanical connection was introduced in this paper.Then,numerical simulation was carried out to analyze some casual factors,unconsidered in previous experiments,on the mechanical behavior of cap-pile joints,including stirrup ratio,steel reinforcement ratio,and effective prestress.Results showed that stirrup spacing had limited influence on the horizontal maximum bearing capacity of nodes.However,a smaller stirrup spacing imposed a greater constraint on the concrete,and also resulted in a gentler decline curve of horizontal bearing capacity.For a larger stirrup spacing,the decline curve of horizontal bearing capacity would be steeper.The following results were also obtained:(1)increasing the effective prestress increased the horizontal bearing capacity of nodes;(2)a higher effective prestress corresponded to greater damage to the pile body,while a lower effective prestress to the pile caps;(3)the ductility and horizontal bearing capacity were improved by using steel reinforcements;and(4)the use of large-diameter steel bars improved the anchorage performance of nodes,causing more damage to the pile body.The simulation results should provide a reliable basis for improvement and application of this type of pile.