轻质高强方钢管轻骨料混凝土...劲X形节点构造和承载力研究_金晖.pdf

Industrial Construction Vol.53,No.4,2023工业建筑2023 年第 53 卷第 4 期125 轻质高强方钢管轻骨料混凝土加劲 X 形节点构造和承载力研究 金晖1郭立湘2赵伟3王万祯4(1.浙江树人学院城建学院,杭州310015;2.浙江中南绿建科技集团有限公司,杭州310052;3.浙江交通职业技术学院钢桥中心,杭州311112;4.宁波大学土木工程与地理环境学院,浙江宁波315211)摘要:为研制轻质高强桁架节点构造及其承载力,对 Q345B 方钢管轻骨料混凝土加劲 X 形节点和基本型节点进行了静力加载试验,考察了支主管间设置加劲板和支主管内浇灌轻骨料混凝土对节点破坏模式和承载力的影响。试验结果表明:加劲节点的破坏模式有加劲板与剪压支管焊缝开裂、剪压支管翼板被加劲板拉开、剪压支管在靠近加劲板外端截面剪压破坏;基本型节点的破坏模式为支主管焊缝开裂;支主管间设置的加劲板明显推迟了节点的屈服和断裂进程,支主管内浇灌轻骨料混凝土有效防止了方钢管屈曲,显著提高了节点承载力,加劲节点的焊缝开裂荷载和极限承载力较基本型节点分别提高 63.3%和 18.3%。根据加劲 X 形节点试验破坏模式,推导了考虑加劲板应力传递和扩散效应的方钢管轻骨料混凝土加劲 X 形节点的加劲板与剪压支管焊缝开裂、剪压支管翼板拉开、剪压支管剪压破坏的力学计算模型和承载力计算式。建议的加劲 X 形节点的承载力计算式的计算误差为-27.8%+3.7%。关键词:方钢管;加劲 X 形节点;轻骨料混凝土;试验;破坏模式;承载力 DOI:10.13204/j.gyjzG23010601浙江省基础公益研究计划项目(LGG21E080001);宁波市社会投资建设科研计划项目(202238)。第一作者:金晖,男,1988 年出生,硕士,工程师。通信作者:赵伟:zhaowei7811 。收稿日期:2023-01-06Research on Structure and Bearing Capacity of Stiffened X-Joints of LightweightAggregate Concrete-Filled High-Strength Square Steel TubesJIN Hui1GUO Lixiang2ZHAO Wei3WANG Wanzhen4(1.College of Urban Construction,Shuren University,Hangzhou 310015,China;2.Zhejiang Zhongnan Green ConstructionTechnology Group,Hangzhou 310052,China;3.Center of Steel Bridge,Zhejiang Institute of Communications,Hangzhou311112,China;4.School of Civil and Environmental Engineering,Ningbo University,Ningbo 315211,China)Abstract:In order to study the structure and bearing capacity of lightweight high-strength truss joints,static loading tests were carried out on X-joints with stiffened plates and basic X-joints of lightweight aggregate(LWA)concrete-filled Q345B steel square tubes.The effects of the stiffened plates between braces and chords and the LWA concrete poured into braces and chords on the failure mode and bearing capacity of X-joints were studied.Tests results showed that the failure modes of stiffened X-joints were weld cracking between stiffened plates and braces under shear and compression,tension failure of brace flange under shear and compression by stiffened plates,and shear and compression failure at sections of braces under shear and compression near stiffened plate outer edge.The failure mode of the basic X-joints was weld cracking between braces and chords.The yield and fracture process of X-joints were delayed and the bearing capacity of X-joints increased significantly due to the stiffened plates between braces and chords.Pouring LWA concrete into braces and chords could effectively prevent buckling of square steel tubes.The weld cracking load and the bearing capacity of stiffened X-joints were 63.3%and 18.3%,respectively,which were higher than those of the basic X-joints.According to the failure modes of stiffened X-joints,the calculation models were established and the bearing capacity calculation formulas were derived considering the effects of stress transfer and diffusion of stiffened plates for fracture of fillets between stiffened plates and braces under shear and compression,flange pulling of shear-pressure braces,shear-compression failure of shear-pressure braces of stiffened X-joints of lightweight aggregate concrete-filled high-strength square steel tubes.The calculation error of the suggested bearing capacity formula for stiffened X-joints was-27.8%to+3.7%.Keywords:square steel tube;stiffened X-joint;LWA concrete;test;failure mode;bearing capacity 0引言钢管桁架结构受力合理、构造简单,在大跨结构中有广阔的应用前景,受到广泛关注1-7。为提高桁架节点承载力,又不过多增加结构自126 工业建筑2023 年第 53 卷第 4 期重,常在支主管内灌注混凝土,以避免中空支主管屈曲和失稳,或在节点区设置加劲板,推迟节点区焊缝断裂进程。Li 等对方钢管加劲 X 形节点进行了试验研究,结果表明,加劲板能延缓钢管局部屈曲,提高节点极限承载力和稳定性1;Xie 等对主管浇灌混凝土的K 型节点的试验结果显示,节点的典型破坏模式有受压支管局部屈曲、受拉支管焊缝开裂2;Chen 等对主管浇筑混凝土的圆钢管 K 型节点进行了试验和数值分析,结果显示,节点的典型失效模式为主管核心区冲剪破坏、主管壁屈服受压和支管局部屈曲3;Idris 等对主管浇灌混凝土的 X 形节点进行了对比试验,结果表明,支管内灌混凝土节点的极限强度大于空心支管节点,圆支管混凝土节点的极限强度大于矩形支管混凝土节点4;陈誉等对主管灌混凝土的 X 形节点和支管灌混凝土的十字形节点的试验结果显示:主管灌混凝土的 X 形节点,支管根部进入塑性,支管灌混凝土的十字形节点,主管进入塑性,支管部分进入塑性5-6;赵必大等考察了支主管夹角对圆钢管 X 形节点平面外抗弯性能的影响,发现主支管夹角较小时,节点域主管壁塑性分布更均匀,节点抗弯性能更好7。以往的研究表明,仅在主管浇灌混凝土的桁架节点,过早发生支管屈曲和失稳、支主管焊缝开裂过早等破坏现象,降低了桁架节点的受力性能。本文研制了支主管间设置加劲板、支主管内均浇灌质量较轻的轻骨料混凝土的 Q345B 方钢管 X形节点构造,对其进行了静力加载试验,考察了加劲板和支主管内浇灌轻骨料混凝土对 X 形节点破坏模式和承载力的影响,推导了方钢管轻骨料混凝土加劲 X 形节点不同破坏模式下的承载力计算式,经与试验值比较,验证了建议的节点承载力计算式的精度。1X 形节点试验概况1.1试验试件设计参照文献8,设计了图 1 所示的高强方钢管轻骨料混凝土桁架基本型 X 形节点试件 BX,用于对比试验。同时衍生设计了图 2 和表 1 所示的支主管间设置加劲板的 X 形节点试件 SX1 SX3,用于考察加劲板构造对高强方钢管轻骨料混凝土 X 形节点受力性能的影响。4 个节点试件均采用 Q345B 钢和 E50 型焊条手工焊接加工,两根壁厚为 4 mm 的方支管沿 45夹角反对称焊接于截面为 200 mm200 mm6 mm 的方主管上;加劲节点中,在距支主管焊缝 40 mm 处焊接厚度为 6 mm 的等腰梯形加劲板。a正立面;b侧立面;c俯视图。图 1基本型 X 形节点试件 BX 的细部构造mmFig.1Details of the basic X-joint specimen BX支主管内浇灌陶粒轻骨料混凝土,配合比为:水 砂 水泥 陶粒=1 3 2.5 3,采用 42.5R级普通硅酸盐水泥,粗、细骨料分别为黏土煅烧陶粒和河砂。支主管内轻骨料混凝土和标准立方体试块均按文献9的规定养护 28 d。a正立面;b侧立面。图 2加劲 X 形节点试件 SX1 SX3 的细部构造mmFig.2Details of stiffened X-joint specimen SX1 SX3表 1各试件的构造参数Table 1Parameters of specimensmm试件参数BXSX1SX2SX3方支管边长801008060加劲板长底边长 1119778加劲板短底边长303030加劲板斜边长10887651.2试验加载方案图 3 为 X 形节点试验加载照片和加载示意,可见:两支管通过端板螺栓连接于铰支座,铰支座采用高强螺栓固接于 H 型钢反力架上,H 型钢反力架固轻质高强方钢管轻骨料混凝土加劲 X 形节点构造和承载力研究 金晖,等127 定于混凝土反力墙上。采用液压千斤顶对主管下端施加轴压力,两支管被动受剪拉和剪压。a加载照片;b加载示意。图 3X 形节点试验加载照片和示意Fig.3Loading picture and sche