Chen Xiaoying, Yang Gang, Zhuo Jing, Zhang Yonghui, Ren Changrui, Qi Longsheng, Du Hanchen, Bu Changming
School of Civil Engineering and Architecture, Chongqing University of Science & Technology, Chongqing 401331, China.
Key Laboratory of Transport Industry of Highway Engineering Technology in Arid Desert Areas, Xin jiang Transportation Science Research Institute Co., Ltd, Xinjiang, 830000, China.
Heliyon. 2024 Mar 14;10(6):e26995. doi: 10.1016/j.heliyon.2024.e26995. eCollection 2024 Mar 30.
There have been many research reports on the reinforcement of small-sized square columns with a cross-section of 200mm-300mm using prestressed carbon fiber-reinforced polymer (CFRP) materials, while there are few studies on piers in bridge and tower columns in cable-stayed bridges with a cross-section of several meters or even tens of meters. The horizontal prestressed steel tendons in the anchorage zone of tower columns in cable-stayed bridge replaced by prestressed CFRP sheets can not only facilitate construction and maintenance, but also have good fatigue resistance. The prestressed CFRP plate is used to reinforce the large-sized tower columns by using a specific device to tension the CFRP plate wrapped around the surface of the members. The tensioning device and test pedestal based on WSGG (wave-shaped-gear-grip) anchor clamping of CFRP plate have been developed in this paper, and the CFRP plate circumferential tensioning tests on the pedestal have been conducted. The test results are as follows: (1) the developed device can achieve circumferential tensioning of single-layer CFRP plate to 0.5ftk of the material, reaching a tensile force of 60kN, and generate effective restraint pressure on a 2-m long composite compression component; (2)The calculation formula for the constraint pressure generated by the circumferential prestressed CFRP sheet on the component has been derived and verified, and the maximum error between the calculated value and the experimental value is within 5%; (3) When iron sheet serves as the interface medium between CFRP plate and compression components, the prestress loss of the CFRP plate tensioned at one end is about 84% and 58%-60% when tensioned at both ends. It can be seen that the effective prestress of the CFRP plate with iron sheet as the interface medium is relatively small. Meanwhile, based on the distribution of compressive stress in the components and the effective pre tension value of CFRP plate, it can be seen that two end tensioning is better than one end tensioning; (4) The tensile stress of CFRP plate along the member is a cubic function when the tension force is 60kN, so it is deduced that the constrained compressive stress generated by CFRP plate on the member is a quadratic function distribution.
关于使用预应力碳纤维增强聚合物（CFRP）材料对横截面为200毫米至300毫米的小型方柱进行加固，已有许多研究报告，而对于桥梁中的桥墩以及斜拉桥中横截面达数米甚至数十米的塔柱，相关研究却很少。用预应力CFRP板替换斜拉桥塔柱锚固区的水平预应力钢绞线，不仅便于施工和维护，而且具有良好的抗疲劳性能。通过使用特定装置对缠绕在构件表面的CFRP板进行张拉，采用预应力CFRP板对大型塔柱进行加固。本文研制了基于WSGG（波形齿夹具）锚固夹紧CFRP板的张拉装置和试验台座，并在试验台座上进行了CFRP板环向张拉试验。试验结果如下：（1）所研制的装置能够实现单层CFRP板环向张拉至材料极限抗拉强度标准值的0.5倍，达到60kN的拉力，并在2米长的复合受压构件上产生有效的约束压力；（2）推导并验证了环向预应力CFRP板对构件产生的约束压力计算公式，计算值与试验值的最大误差在5%以内；（3）当铁皮作为CFRP板与受压构件之间的界面介质时，一端张拉时CFRP板的预应力损失约为84%，两端张拉时为58% - 60%。可见，以铁皮作为界面介质的CFRP板有效预应力相对较小。同时，根据构件中压应力分布和CFRP板有效预拉力值可知，两端张拉优于一端张拉；（4）当拉力为60kN时，CFRP板沿构件的拉应力呈三次函数关系，由此推断CFRP板对构件产生的约束压应力呈二次函数分布。
