薄壁钢箱混凝土短柱的弱约束效应  

Weak confinement effect of concrete-filled thin-walled steel box short column

作　　者：王欢 康玲 陈明 邹圻 牟廷敏 WANG Huan;KANG Ling;CHEN Ming;ZOU Qi;MU Tingmin(Sichuan Highway Planning,Survey,Design and Research Institute Ltd.,Chengdu 610041,China;Bridge and Structural Engineering Laboratory of Sichuan Province,Chengdu 610041,China)

机构地区：[1]四川省公路规划勘察设计研究院有限公司,成都610041 [2]四川省桥梁与结构工程实验室,成都610041

出　　处：《哈尔滨工业大学学报》2024年第11期162-170,共9页Journal of Harbin Institute of Technology

基　　金：四川省交通运输科技项目(2022-ZL-07,2022-ZL-08);四川省科技计划资助项目(2023YFG0376);企业级横向科研项目([2022]94号)。

摘　　要：为研究薄壁钢箱混凝土的弱约束效应,开展了9个薄壁钢箱混凝土短柱轴压试验和6个圆形钢管混凝土、普通钢筋混凝土短柱对照组试验,获得了构件破坏模式、荷载-位移曲线、极限承载能力、组合强度、轴压刚度、截面应变分布等力学行为。与圆形钢管混凝土、普通钢筋混凝土构件进行对比分析,系统阐明了薄壁钢箱对混凝土的弱约束效应、薄壁钢箱与混凝土的变形协调关系。基于薄壁钢箱对混凝土强度的提升贡献,建立了考虑弱约束效应的薄壁钢箱混凝土短柱轴压承载力计算方法。结果表明:极限承载力和轴压刚度随含钢率、约束效应系数的增大而增大,随钢板宽厚比的增大而减小;弱约束效应下,薄壁钢箱在30%~40%极限荷载时局部鼓曲,此后钢箱与混凝土出现变形不协调现象,混凝土达到极限状态时呈脆性压溃,截面有效承压面积减小、下降段陡峭、承载力下降迅速,但后期依靠钢箱维持承载而延性较好;矩形钢箱混凝土和圆形钢管混凝土在小含钢率情况下,弹性、弹塑性阶段的力学行为相似、极限承载力和轴压刚度相近,但圆形截面呈延性破坏且下降段约束效应优于矩形截面;薄壁钢箱混凝土比普通钢筋混凝土承载能力提升约15%、轴压刚度提升约5%,且施工无需绑扎钢筋和安拆模板,在结构方案设计时具备竞争优势与潜力。所提承载力计算方法经验证精度可靠,可为薄壁钢箱混凝土结构设计提供指导。To investigate the weak confinement effect of concrete-filled thin-walled steel box(CFTSB),the axial compression tests of 9 CFTSB short columns and 6 control group tests of circular concrete-filled steel tube(CFST)and ordinary reinforced concrete(RC)short columns are carried out.The mechanical behaviors such as failure mode,load-displacement curve,ultimate bearing capacity,composite strength,axial compression stiffness,and sectional strain distribution were obtained,and the weak confinement effect of CFTSB and the deformation coordination relationship between thin-walled steel box and concrete are described in detail by comparing with circular CFST and ordinary RC components.Based on the contribution of thin-walled steel box to the strength improvement of concrete,an axial compressive capacity calculating method of CFTSB short column with weak confinement effect is established.The results show that the ultimate bearing capacity and axial compression stiffness increase with the increase of steel ratio and confinement coefficient,but decrease with the increase of width-to-thickness ratio.Under the weak confinement effect,the thin-walled steel box partially buckled at 30%-40%of the ultimate load,and then the deformation of the steel box and concrete appeared uncoordinated phenomenon.The concrete is crushed when it reached ultimate state,and the bearing capacity declined rapidly because of the decrease of effective bearing area,but the ductility during later period is better maintained by the steel box.In the case of small steel ratio,the mechanical behavior of CFTSB and CEST is similar in elastic and elastic-plastic stage as well as similar ultimate bearing capacity and axial compressive stiffness,but the circular section shows ductile failure and the constraint effect of falling stage is better than that of the rectangular section.The bearing capacity and stiffness of CFTSB are about 15%and 5%higher than that of ordinary RC,respectively,and the construction does not need to tie steel bars and install and disassembl

关 键 词：薄壁钢箱混凝土 组合结构 弱约束效应 变形协调关系 轴压试验 

分 类 号：TU398.9[建筑科学—结构工程] TU317.1