火灾后高强螺栓连接预拉力松弛试验  

Experiment on pretension force relaxation of high-strength bolt connections after fire

作　　者：陈建锋[1] 周天华[1] 

机构地区：[1]长安大学建筑工程学院,陕西西安710061

出　　处：《长安大学学报（自然科学版）》2014年第3期86-91,共6页Journal of Chang’an University(Natural Science Edition)

基　　金：中国博士后科学基金资助项目(2011M501428)

摘　　要：针对火灾后高强螺栓预拉力松弛现象,通过对81个受力状态下的高强螺栓试件模拟过火试验,分别加热至不同高温,再经不同方式冷却后测定螺栓预拉力。研究了高温冷却后高强螺栓预拉力松弛变化规律。基于试验数据分析,提出了经高温自然冷却以及消防喷水冷却至常温后,高强螺栓预拉力松弛系数计算公式。研究结果表明：高强螺栓经历300℃高温冷却后预拉力损失大约15%~40%,500℃高温后高强螺栓预拉力损失大约90%;自然冷却后螺栓比喷水冷却螺栓预拉力松弛程度大,且随螺栓杆径的增大这种差距越大;螺栓型号的不同,对自然冷却后高强螺栓预拉力松弛影响不明显,对高温喷水冷却后高强螺栓预拉力松弛影响表现为螺栓杆直径越小,高温喷水冷却后预拉力损失越大。Aimed at pretension force relaxation phenomenon of high-strength bolt after fire,81specimens under pretension state were heated to different temperatures respectively and cooled down to room temperature by different ways to test their pretension forces and study the change regulations of pretension force relaxation.Based on the analysis of experiment results,the formula for pretension force relaxation coefficient after high temperature was put forward.The results indicate that pretension force of high-strength bolt loses about 15%~40% after heated to300℃and cooled and 90%after heated to 500℃and cooled;Pretension force relaxation degree of high-strength bolt after natural cooled is larger than that of injecting water cooling.With the increase of bolt rod diameter,this gap is bigger.Different bolts have not obvious difference on pretension force relaxation for natural cooling,instead,for injecting water cooling the smaller the bolt diameter,the more the pretension force relaxation.

关 键 词：桥梁工程 高强螺栓连接 火灾后 预拉力松弛 实用计算公式 

分 类 号：U448.36[建筑科学—桥梁与隧道工程]