正对称Pratt桁架直腹杆受压大偏心N型圆钢管节点静力性能实验研究  

EXPERIMENTAL RESEARCH ON STATIC BEHAVIOR OF BIG ECCENTRIC CIRCULAR HOLLOW SECTION N-JOINTS WITH VERTICAL BRACE UNDER COMPRESSION IN SYMMETRICAL PRATT TURSS

作　　者：陈誉[1] 刘飞飞[1] 

机构地区：[1]华侨大学土木工程学院,福建泉州362021

出　　处：《工程力学》2011年第11期170-177,共8页Engineering Mechanics

基　　金：国家自然科学基金项目(51008133);福建省自然科学基金计划项目(2010J01299);大连理工大学海岸和近海工程国家重点实验室基金项目(LP0705);桥梁结构工程交通行业重点实验室开放基金项目(CQSLBF-Z07-1);泉州市第一批技术研究与开发项目(重点项目)(2009Z48)

摘　　要：对在正对称Pratt桁架中出现的直腹杆受压大偏心N型圆钢管节点的静力性能进行了单调加载的实验研究。实施了4个负向大偏心、4个正向大偏心和1个无偏心直腹杆受压N型圆钢管节点实验。该文介绍了节点实验方案,考察了直腹杆受压大偏心圆钢管节点破坏现象,给出了竖向荷载-端位移曲线以及应变强度分布曲线,并将偏心率对节点极限承载力、刚度和延性的影响进行了讨论。实验研究结果表明:节点实验值基本接近刚接理论值,节点可以按照刚接节点处理;节点由负向大偏心过渡到正向大偏心率为0.25过程中,随着偏心率的增大极限承载力逐渐增大,在偏心率为0.25时节点的极限承载力达到最大,随着节点偏心率从0.25增加到1.00,节点极限承载力又逐渐减小;不论中国还是欧洲规范在负向大偏心时计算值均为一固定值与实验结果完全不符,且其计算结果偏于不安全;节点变为正向大偏心后由于两腹杆之间间隙较大,N型节点就逐步过渡到单独的两个Y型节点,节点形式的彻底变化导致两规范值小于实验值。To study the static behavior of big eccentric circular hollow section N-joints with vertical bracesunder compression in a symmetrical Pratt truss, four big negative eccentric specimens, four big positive eccentric specimens and one non-eccentric specimen were tested under monotonic loading. The test procedure, joint failure phenomenon, vertical jacket load-displacement curves and strain distribution curves were presented in the paper. The effect of eccentricity on ultimate capacity, stiffness and ductility of the joints was also studied. A comparison between experimental and theoretical results shows that big eccentric CHS N-joints can be regarded as rigid connection. When joint eccentricity is negative or is less than 0.25, the ultimate capacity of joints increases with the eccentricity, then it decreases when the eccentricity is between 0.25 and 1.0. As for the ultimate capacity of joints with large negative eccentricity, neither Chinese code nor Euro code yields results agreeing well withexperimental results and neither is conservative. For the N-joint where the two diagonal bars are well apart, it can be treated as two Y-joints.

关 键 词：正对称Pratt桁架 直腹杆受压 大偏心N型圆钢管节点 静力性能 实验研究 极限承载力 

分 类 号：TU392.3[建筑科学—结构工程]