摘要
针对焊接空间网架结构在服役期内,随使用年限增加而导致结构刚度逐渐降低,加剧结构风致疲劳损伤,提出对结构进行全寿命期风致疲劳分析,以研究结构整个服役期风致抗疲劳性能,保证结构使用安全。通过分析焊接节点与杆件之间连接刚度随裂缝损伤变化的关系,建立网架结构连接刚度可变模型;通过高周疲劳试验,获得节点与杆件之间焊材的应力-寿命(S-N)曲线及疲劳参数;对结构进行风致响应分析,得到结构杆件连接处的应力时程,利用雨流计数法对应力时程进行循环计数,采用Basquin模型的疲劳寿命估算公式和Miner线性累加损伤理论,得到杆件连接处的累积疲劳损伤值和疲劳寿命。以武汉体育中心游泳馆屋顶网架结构为背景,分析了该结构在无焊接缺陷、有10%的焊接缺陷随机分布和最不利分布三种工况下的100年使用期内,随服役期增加、结构刚度不断降低时的所有杆件疲劳损伤程度。结果表明:网架结构在服役早期,杆件连接处就出现了疲劳损伤和连接刚度降低,随使用年限增加,结构连接刚度进一步降低,疲劳损伤程度也不断加剧,发生连接疲劳破坏的杆件数量大幅增加;特别是有焊接初始缺陷时,结构刚度降低更快,发生连接疲劳破坏的杆件数量更多;即使在良态风环境下,也有杆件连接处发生了疲劳破坏。
Due to the gradual decrease of structural stiffness in service life, the wind-induced fatigue damage in welded space grid structures is aggravated, therefore, the whole-life fatigue analysis method of structures under wind load was proposed to investigate the wind-induced fatigue resistance performance of the structure during the whole life and ensure its safety. The variation of connection stiffness between the welded joints and rods with the crack length was analyzed to establish the variable stiffness model of joints in grid structures. Stress-life(S-N) curves and fatigue parameters of welding materials between joints and rods were obtained by high-cycle fatigue test. The wind-induced response of the structure was analyzed to obtain stress time history of the structural connection, whose cyclic count was calculated using the rain flow counting method. Moreover, the cumulative fatigue damage value and fatigue life of the rod connection were estimated by the Basquin evaluation model of fatigue life and Miner’s linear cumulative damage theory. Taking the roof grid structure of the natatorium of Wuhan Sports Center as engineering background, this paper analyzes the fatigue damage degree of all rods of the structure in the service life of 100 years, accounting for the gradual decrease of structural stiffness with the increase of service life and considering three working conditions: no welding defects, 10% random distributed welding defects and the most unfavorable distribution of welding defects. The results show that the fatigue damage and reduction of connection stiffness appear at the members in the early service period. With the increase of service life, the connection stiffness of structure further decreases, the fatigue damage degree also aggravates. The number of rods with connection fatigue damage increases greatly. With initial welding defects, the structural stiffness decreases rapidly, and more rods encounter joint fatigue failure. Even in good wind environment, fatigue failure may occur at some joint
作者
刘晖
倪新舟
陈世超
李浩
瞿伟廉
LIU Hui;NI Xinzhou;CHEN Shichao;LI Hao;QU Weilian(Hubei Key Laboratory of Roadway Bridge&Structure Engineering,Wuhan University of Technology,Wuhan 430070,China)
出处
《建筑结构学报》
EI
CAS
CSCD
北大核心
2021年第11期105-115,共11页
Journal of Building Structures
基金
国家自然科学基金项目(51438002,51078301)
湖北省自然科学基金项目(2018CFB645)。
关键词
网架结构
风致疲劳
全寿命期
刚度可变
焊接缺陷
grid structure
wind-induced fatigue
whole life
variable stiffness
welding defect
