邓宗才,孙 彤,李佳跃
AuthorsHTML:邓宗才，孙 彤，李佳跃
AuthorsListE:Deng Zongcai,Sun Tong,Li Jiayue
AuthorsHTMLE:Deng Zongcai，Sun Tong，Li Jiayue
Unit:城市与工程安全减灾省部共建教育部重点实验室(北京工业大学)，北京 100124
Unit_EngLish:Key Laboratory of Urban Security and Disaster Engineering (Beijing University of Technology)， Ministry of Education，Beijing 100124，China
Abstract_Chinese: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．
Abstract_English: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\u0002cle 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\u0002filled 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.
Keyword_Chinese: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
Keywords_English:high-strength steel tube；ultra-high performance concrete (UHPC)；flexural mechanical properties； reduction factor；flexural stiffness；flexural capacity

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