螺锁式预应力混凝土异型方桩连接接头受弯性能研究

Study on flexural behavior of prestressed concrete special-shaped square pile connection joint with bolt-shackle

为实现桩体内受力主筋的有效连接,研发了一种新型螺锁式预应力混凝土异型方桩连接接头。通过3种规格异型方桩连接接头试件的足尺受弯性能试验,研究了方桩接头试件的抗裂性能、承载能力和破坏形式。试验结果表明:受弯试验测得的各螺锁式预应力混凝土异型方桩连接接头试件极限抗弯承载力均大于理论计算得到的各试件桩身极限抗弯承载力;受弯破坏发生在试件跨中连接接头部位,拼接界面底部螺锁式机械连接件因预应力钢棒或预应力钢棒镦头被拉断而失效,受压区混凝土未出现明显压碎现象。

In order to obtain the effective connection of the main reinforcements in the pile body, a new type of bolt-shackle connection joint for prestressed concrete special-shaped square piles was developed. The full-scale flexural behavior tests of three types of special-shaped square pile connection joint specimens were carried out to study the crack resistance, bearing capacity and failure modes of the square pile joint specimen. The experiment results show that the ultimate flexural bearing capacity of specimens of the prestressed concrete special-shaped square pile connection joint with bolt-shackle tested by the flexural tests is greater than the ultimate flexural bearing capacity of each sample pile that obtained by theoretical calculation. The flexural failure occurs at the connection joint of the mid-span of test specimens, and some bolt-shackle mechanical connectors at the bottom of the splicing interface are invalid due to the rupture of the prestressed steel bars or the upsetting heads of the prestressed steel bars, without obvious crushing of concrete in the compression zone.