土木与环境工程学报  2019, Vol. 42 Issue (4): 104-111   PDF
 Article Options PDF Abstract Figures References 扩展功能 把本文推荐给朋友 Email Alert RSS RIS（文献管理工具） 本文作者相关文章 祝明桥 李志彬 王瑶 张紫薇

Tensile test of pultruded GFRP pipe connected with steel pipe
Zhu Mingqiao , Li Zhibin , Wang Yao , Zhang Ziwei
Department of Civil Engineering, Hunan University of Science and Technology, Xiangtan 411201, Hunan, P. R. China
Abstract: The reliable connection of pultrusion forming GFRP pipe joints is a prerequisite to ensure the normal operation of the components. In order to explore its tensile connection performance, two kinds of connection modes of bonding connection and bolt connection in GFRP pipe and steel pipe connector are adopted in this study to carry out the tensile test. The distribution characteristics, force mechanism, failure process and the influence of bonding length on load-bearing capacity of glue layer shear stress along the length direction were studied in the adhesive bonding test. The results show that the shear stress of the glue layer is large at both ends and small in the middle along the length direction at the initial stage of loading. As the load increased, the stress gradually shifted towards the loading end of the glue layer. The increase of bonding length can significantly improve the load-bearing capacity of the connecting parts, but when the length reaches 1.6 times of the pipe diameter, the increase of the bonding length is not sensitive to the increase of the load-bearing capacity any more. Therefore, the 1.6 times the pipe diameter can be regarded as the effective bond length of the GFRP pipe. Additionally, the influence of e/d(edge distance/bolt diameter) and bolt row number on the connection load-bearing capacity and failure mode were studied in the bolt connection experiment. The results show that when e/d is equal to 7, the load-bearing capacity reaches the maximum value and the main failure mode is extrusion failure. According to the relationship between the bolt row number and the load-bearing capacity, the corresponding reduction coefficient can be readily deduced for calculating the load-bearing capacity.
Keywords: GFRP pipe    adhesive bonding    bolt connection    tensile test

1 GFRP管材连接试验
1.1 试验材料及构件设计

 图 1 GFRP管材与钢管连接件配合连接示意图 Fig. 1 Schematic diagram of matching connection between GFRP pipe and steel pipe fittings

1.2 试件设置
1.2.1 胶接连接参数设置

 图 2 胶接连接构件实物图 Fig. 2 Sectional view of placement of fiberglass in GFRP tube

1.2.2 机械连接参数设置

 图 3 单排螺栓连接设置图 Fig. 3 Single row bolt connection setup diagram

 图 4 多螺栓连接GFRP管栓孔设置示意图 Fig. 4 Bolt setting of multiple bolted connection GFRP tube

 图 5 螺栓连接构件实物图 Fig. 5 Components of bolted connection

1.3 加载及测量指标

2 胶接实验结果与分析
2.1 荷载-拉伸变形关系及破坏模式

 图 6 不同胶接长度的荷载-拉伸变形曲线 Fig. 6 Load-tensile deformation curve of different bonding lengths

 图 7 GFRP管材胶接破坏图 Fig. 7 Debonding failure of GFRP tube

2.2 胶层剪应力分布特征

 $\tau_{i}=\frac{\left(\varepsilon_{i+1}-\varepsilon_{i}\right) E_{\mathrm{s}} A_{\mathrm{s}}}{\pi d h_{i}}$ (1)

 图 8 剪切应力在不同胶接长度上的分布 Fig. 8 Distribution of shear stress on different bonding lengths

2.3 胶接连接受力机理及破坏过程分析

 图 9 胶接连接节点处胶层变形示意图 Fig. 9 Diagram of adhesive layer deformation at joint joints

 图 10 胶接界面失效过程 Fig. 10 Failure process of bonding interface

2.4 胶接长度对承载力的影响

 图 11 胶接长度与承载力及平剪切应力的关系 Fig. 11 Relationship between bonding length ad capacity and mean shear stress

3 螺栓连接实验结果与分析
3.1 端距对单螺栓连接性能的影响

 图 12 e/d比值与承载力的关系 Fig. 12 Relationship between e/d and ultimate load

 图 13 e/d比值变化对破坏形式影响 Fig. 13 Effect of change in e/d on failure mode

3.2 螺栓排数对连接性能影响

 图 14 螺栓排数与承载力关系 Fig. 14 Relationship between row number of bolts and capacity

3.3 螺栓连接承载力计算

 \begin{aligned} \beta_{2} &=\frac{P_{2}}{n P_{\mathrm{br}}}=\frac{37.921}{2 \times 23.986}=0.79 \\ \beta_{3} &=\frac{P_{3}}{n P_{\mathrm{br}}}=\frac{52.844}{3 \times 23.986}=0.73 \\ \beta_{4}=& \frac{P_{4}}{n P_{\mathrm{br}}}=\frac{60.355}{4 \times 23.986}=0.629 \end{aligned}

 $P_{n}=2 n \sigma_{\mathrm{bn}} t d \beta_{i}$ (2)

4 结论

1) 胶接连接中胶层剪应力沿长度方向分布不均匀，随着荷载的增加，胶层剪应力峰值由胶接端朝中间段胶层转移。

2) 胶接连接中，增加胶接长度可以提高极限承载力，但胶接长度与承载力并不成线性关系。前期增加胶接长度能显著提高构件承载力，但当长度达到管径的1.6倍(68 mm)后，再增加胶接长度对承载力提升并不大，由此可考虑将1.6倍管径作为拉挤型GFRP管材的有效胶接长度。

3) 拉挤型GFRP管材螺栓连接在保证不发生拉伸破坏时，端距与栓径的比值在e/d≥7、排距与螺栓直径比值p/d≥8范围中可保证连接破坏为偏安全的破坏形式-挤压破坏。

4) 对于中等厚度(厚度为5 mm左右)的拉挤GFRP管型材两种连接方式，胶接连接效率较高，而螺栓连接效率远低于胶接连接。综合考虑连接效率和制作工艺等因素，建议选择胶接连接方式。