| 基于热点应力法的矩形钢管混凝土组合桁梁桥节点疲劳评估 |
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| 引用本文： | 姜磊,刘永健,龙辛,王文帅,马印平.基于热点应力法的矩形钢管混凝土组合桁梁桥节点疲劳评估[J].交通运输工程学报,2020,20(6):104-116. |
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| 作者姓名： | 姜磊 刘永健 龙辛 王文帅 马印平 |
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| 作者单位： | 1.长安大学 公路学院, 陕西 西安 7100642.女王大学 土木工程系, 安大略 金斯顿 K7L3N6 |
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| 基金项目： | 国家自然科学基金;中央高校基本科研业务费专项 |
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| 摘 要： | 为准确评估矩形钢管混凝土组合桁梁桥节点疲劳性能, 引入热点应力法, 可通过平面杆系模型、空间杆系模型和三维实体模型计算节点焊趾处的热点应力幅, 并通过对52个节点疲劳试验数据回归分析, 拟合得到热点应力幅-循环次数曲线; 选取陕西黄延高速一座矩形钢管混凝土组合桁梁桥为典型案例进行节点疲劳评估, 并对原有节点设计方案的构造进行优化。研究结果表明: 相比于墩顶矩形钢管混凝土节点, 跨中矩形钢管节点热点应力幅更大, 为60.1 MPa, 发生在主管表面, 但是小于欧洲规范Eurcode中的容许疲劳强度71 MPa, 满足疲劳设计要求; 对跨中疲劳易损节点进行设计构造优化, 原设计矩形钢管节点变为矩形钢管混凝土节点后, 管内混凝土改变了节点局部刚度, 使相贯线焊趾处应力分布均匀, 支、主管表面热点应力幅平均降低25.1%, 对原设计节点进行焊缝后处理, 可有效消除焊接初始拉应力, 改善节点疲劳性能, 支、主管表面热点应力幅平均降低14.9%;采用空间杆系模型对优化后的跨中矩形钢管混凝土节点进行疲劳评估, 支、主管表面最大热点应力幅分别为58.9、54.1 MPa, 大于三维实体模型计算得到的支管和主管表面最大热点应力幅45.2、47.1 MPa, 空间杆系模型计算结果偏保守, 且无法像三维实体模型一样准确计算不同热点位置的疲劳效应, 也无法准确判断疲劳开裂起始位置。
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| 关 键 词： | 桥梁工程 矩形钢管混凝土 组合桁梁桥 节点 热点应力法 疲劳评估 |
| 收稿时间： | 2020-08-10 |
Fatigue assessment of joints in concrete-filled rectangular hollow section composite truss bridges based on hot spot stress method |
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| JIANG Lei,LIU Yong-jian,LONG Xin,WANG Wen-shuai,MA Yin-ping.Fatigue assessment of joints in concrete-filled rectangular hollow section composite truss bridges based on hot spot stress method[J].Journal of Traffic and Transportation Engineering,2020,20(6):104-116. |
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| Authors: | JIANG Lei LIU Yong-jian LONG Xin WANG Wen-shuai MA Yin-ping |
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| Affiliation: | 1.School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China2.Department of Civil Engineering, Queen's University, Kingston K7L3N6, Ontario, Canada |
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| Abstract: | In order to accurately assess the fatigue behaviour of joints in concrete-filled rectangular hollow section steel tubular composite truss bridges, the hot spot stress method was introduced. The hot spot stress range at the weld toe can be determined by the planar frame model, spatial frame model, and three-dimensional solid model. Based on 52 fatigue test data of joints, the hot spot stress range-cycle number curves were obtained through the regression analysis. A concrete-filled rectangular hollow section steel tubular composite truss bridge located at the Huangyan highway was selected as the typical case, the fatigue behaviour of the joint was assessed, and original design details were optimized. Research results show that compared with the concrete-filled rectangular hollow section steel tubular joint on the top of the pier, the hot spot stress range in the rectangular hollow section joint at mid-span is higher, which equals to 60.1 MPa, and occurs on the main surface of the chord. However, it is less than the allowable value of 71 MPa determined according to Eurcode, thereby the design of the joints met the requirements. The optimization of design details on the fatigue vulnerable joint at mid-span is carried out. After filling the hollow section with concrete, the local joint stiffness changed, resulting in a more uniform stress distribution at the weld toe intersection. The hot spot stress ranges of brace and chord surface decrease by 25.1% on average. The post-weld treatment of the original designed joint can effectively eliminate the initial tensile stress of the welding and improve the fatigue performance of the joint. The hot spot stress ranges in the brace and chord surface decreased by 14.9% on average. Using spatial frame model to assess the fatigue behaviour of optimized joint at mid-span, the maximum hot spot stress ranges on the brace and chord are 58.9 and 54.1 MPa, respectively, both less than the results of 45.2 and 47.1 MPa calculated by using the three-dimensional solid model. It demonstrats that the result obtained by using the spatial frame model is more conservative, and the fatigue effects of different hot spots can not be calculated as accurately as the three-dimensional solid model, nor can the initial position of fatigue cracking be judged accurately. |
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