Experimental study on the bending performance of assembled joints for composite circular tubes

doi:10.19936/j.cnki.2096-8000.20250328.001

Abstract

Abstract: To enable the rapid on-site assembly and construction of lightweight fiber reinforced polymer (FRP) emergency footbridge, an assembled composite tubular joint that incorporates pre-tightened toothed connection (PTTC) and metal tube threads was proposed. Four-point bending tests were conducted on two types of specimens with different local structures to compare and analyze their mechanical behaviors, such as failure modes and ultimate load-bearing capacities. The results indicate that the proposed assembled composite tubular joint not only facilitates rapid assembly but also exhibits high flexural behavior, making it suitable for composite tubular beam configuration in emergency footbridges. When the assembled joint was subjected to bending loads, the absence of a chamfer on the metal sleeve of the PTTC led to localized transverse shear failure and initial damage to the composite tube. Thereafter, compression and tension stresses were induced on the upper and lower side of the composite tube, respectively, resulting in premature longitudinal fiber failure. Adjacent composite tubes experienced typical bending-induced delamination. However, when a chamfer was introduced, there was no obvious local transverse shear failure of the composite tube at the corresponding junction of the dissimilar materials, which shows typical bending failure characteristics. Unlike with axial loading, when the joints are subjected to bending loads, optimizing the chamfer design at the metal sleeve's end is crucial. This optimization not only improves the failure mode of the assembled composite tubular joint but also enhances its bearing capacity by approximately 15%.

Key words: fiber reinforced composite, emergency pedestrian bridge, assembled structure, tubular joint, pre-tightened teeth connection, flexural behavior

CLC Number:

TB332

YUAN Shuai, ZHANG Dongdong, DUAN Jinhui, GAO Yifeng, ZHANG Yunqiang, MO Changjin. Experimental study on the bending performance of assembled joints for composite circular tubes[J]. COMPOSITES SCIENCE AND ENGINEERING, 2025, 0(3): 1-6.

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