摘要
高强钢管约束超高性能混凝土(ultra-high performance concrete,UHPC)具有自重轻、承载力及刚度高和耐火性能好的优势,在工程中具有良好的应用前景.为研究高强钢管约束UHPC构件在纯弯作用下的力学性能,对1个实心普通强度钢管约束UHPC梁、3个实心高强钢管约束UHPC梁、1个方套方中空夹层高强钢管约束UHPC梁和3个方套圆中空夹层高强钢管约束UHPC梁进行了两点弯曲试验.研究了高强钢管约束UHPC梁在纯弯荷载下的破坏形式以及含钢率、钢材屈服强度和截面组合形式对梁抗弯承载力和抗弯刚度的影响.试验结果表明:高强钢管约束UHPC梁弯矩-曲率的变化过程分为3个阶段:弹性阶段、弹塑性阶段和强化阶段,破坏时表现出良好的延性.高强钢管UHPC梁的受压区未出现局部凸起.钢管厚度为4 mm、6 mm和8 mm的实心高强钢管UHPC梁含钢率分别为0.116、0.188和0.253,相比4 mm厚的实心高强钢管UHPC梁,6 mm和8 mm厚的实心高强钢管UHPC梁抗弯承载力分别提高35.9%、58.5%;使用抗弯刚度分别提高12.9%、32.4%.相比于外钢管取6 mm厚的实心和方套方中空夹层钢管UHPC梁,方套圆中空夹层钢管UHPC梁的抗弯承载力分别提高26.8%、10.3%;使用抗弯刚度分别提高3.5%、4.5%.由于高强度微细钢纤维良好的阻裂和控裂能力,高强钢管约束UHPC梁在弹塑性变形阶段的刚度较高.受力过程中UHPC的弹性模量衰减速率低于普通混凝土,因此,基于叠加法,考虑钢纤维UHPC的控裂能力,建立了高强钢管约束UHPC梁使用阶段抗弯刚度的计算式,理论计算值与试验值吻合良好.
Ultra-high performance concrete(UHPC)for high-strength steel tubes has a good application prospect in engineering due to its advantages of light deadweight,high bearing capacity and rigidity,and good fire resistance.To study the mechanical properties of the UHPC-filled high-strength steel tube component under pure bending,a two-point bending test was conducted on eight beams.The beams included one UHPC-filled ordinary steel tube beam,three UHPC-filled high-strength steel tube beams,one UHPC-filled double-skin high-strength steel tube(UHPCFDST)beam with an inner square tube,and three UHPCFDST beams with an inner circular tube.The failure modes of the UHPC-filled high-strength steel tube beams under pure bending load and the influences of steel ratio,steel yield strength,and section combination on the flexural capacity and flexural rigidity of the beam were studied.Test results show that the bending moment-curvature changes the process of the UHPC-filled high-strength steel tube and is divided into three stages:elastic,elastic-plastic,and hardening stages.It shows good ductility during failure.Moreover,no local protrusion in the compression zone is observed.The steel ratios of the UHPC-filled high-strength steel tube beams with 4 mm,6 mm and 8 mm thicknesses of outer steel tubes are 0.116,0.188 and 0.253,respectively.Compared with the 4 mm UHPC-filled high-strength steel tubes,the flexural capacities of 6 mm and 8 mm are increased by 35.9%and 58.5%,while the flexural rigidities are increased by 12.9%and 32.4%,respectively.Compared with the UHPC-filled high-strength steel tube beams and the UHPCFDST beam with an inner square tube and a 6 mm thickness outer steel tube,the bending capacity of the UHPCFDST beams with an inner cir-cle tube is increased by 26.8%and 10.3%,respectively,and the flexural rigidity is increased by 3.5%and 4.5%,respectively.Due to the good crack resistance and crack control ability of high-strength microsteel fiber,the UHPC-filled high-strength steel tube beam has a high stiffness in the elastic-plastic deformation stage.The attenuation rate of the elastic modulus of UHPC is lower than that of ordinary concrete in the process of stress.Therefore,based on the superposition method,considering the crack control ability of steel fiber UHPC,the formula for calculating the flexural rigidity of the UHPC-filled high-strength steel tube beam in the service stage was established.The theoretical calculated value agrees well with the experimental value.
作者
邓宗才
孙彤
李佳跃
Deng Zongcai;Sun Tong;Li Jiayue(Key Laboratory of Urban Security and Disaster Engineering(Beijing University of Technology),Ministry of Education,Beijing 100124,China)
出处
《天津大学学报（自然科学与工程技术版）》
EI
CAS
CSCD
北大核心
2021年第11期1111-1120,共10页
Journal of Tianjin University：Science and Technology
基金
北京市教委科技重点资助项目(KZ201810005008).
关键词
高强钢管
超高性能混凝土
受弯力学性能
折减系数
抗弯刚度
抗弯承载力
high-strength steel tube
ultra-high performance concrete(UHPC)
flexural mechanical properties
reduction factor
flexural stiffness
flexural capacity
