摘要
为准确预测钢管混凝土桁式拱桥节点疲劳寿命,提出一种基于热点应力的疲劳评估方法。该方法采用全桥多尺度三维有限元模型计算节点热点应力幅,并进行回归分析得到钢管混凝土节点的热点应力幅S~N曲线。基于该方法对一座已建成的钢管混凝土桁式拱桥进行节点疲劳评估。结果表明:疲劳易损部位位于1/4跨附近的拱肋上弦节点,起始裂纹位于节点主管表面的冠点处;采用《公路钢结构桥梁设计规范》(JTG D64—2015)中的疲劳荷载计算模型Ⅱ和疲劳荷载谱计算得到的疲劳寿命分别为20210049次和27311265次,采用疲劳荷载谱计算时多车效应纵向修正为14.9%;采用《公路钢结构桥梁设计规范》预测的节点疲劳寿命偏低,导致设计偏于保守。
For the arch bridge that has the arch composed of concrete-filled steel tubes,the fatigue life of joints assessed following the current codes is considered conservative.To address this issue,a fatigue life assessing method based on hot spot stress is presented.By which,a multi-scale finite element model of the full bridge is built up to calculate the hot spot stress range of truss joints,thereafter regression analysis is carried out to obtain the S-N curve.The method has been applied to the fatigue life assessment of an already-completed truss arch bridge of similar type.According to the study,the fatigue sensitive locations are at about the quarter points of the arch,nearing to the joints of the upper chords of the arch.The incipient cracks are observed at the crowns of the chord tube surface of the joints.The fatigue lives calculated by the fatigue load computing modelⅡin the Specifications for Highway Steel Bridge(JTG D64-2015)and calculated depending on the fatigue load spectrum are 20210049 and 27311265 cycles,respectively,as a result,the longitudinal modification factor for multiple vehicle effect reaches up to 14.9%when using fatigue load spectrum for calculation.It indicates that the fatigue life of joints assessed following the Specifications for Highway Steel Bridge is smaller,consequently,the design tends to be conservative.
作者
姜磊
刘永健
刘彬
龙辛
蒲北辰
JIANG Lei;LIU Yong-jian;LIU Bin;LONG Xin;PU Bei-chen(School of Highway,Chang′an University,Xi′an 710064,China;CSCEC AECOM Consultants Co.,Ltd.,Lanzhou 730030,China;CCCC Second Highway Consultants Co.,Ltd.,Wuhan 430056,China)
出处
《桥梁建设》
EI
CSCD
北大核心
2022年第3期69-76,共8页
Bridge Construction
基金
国家自然科学基金项目(52008026)
中国博士后科学基金面上项目(2021M692746)
陕西省自然科学基础研究计划资助项目(2021JQ-272)。
关键词
钢管混凝土桁式拱桥
节点
热点应力法
疲劳评估
疲劳寿命
应力集中系数
有限元法
concrete-filled steel tubular truss arch bridge
joint
hot spot stress method
fatigue assessment
fatigue life
stress concentration factor
finite element method