掺钢纤维无配筋UHPC矩形梁抗扭性能试验研究  

Experimental Study on Steel Fiber Reinforced UHPC Rectangular Beams Without Conventional Steel Reinforcement

作　　者：周聪 汪建群[1,2] 贾文博 祝明桥[1] 罗许国[1] ZHOU Cong;WANG Jian-qun;JIA Wen-bo;ZHU Ming-qiao;LUO Xu-guo(Hunan Provincial Key Laboratory of Structures for Wind Resistance and Vibration Control,Hunan University of Science and Technology,Xiangtan 411201,China;Key Laboratory of Bridge Engineering Safety Control by Department of Education,Changsha University of Science&Technology,Changsha 410114,China)

机构地区：[1]湖南科技大学结构抗风与振动控制湖南省重点实验室,湖南湘潭411201 [2]长沙理工大学桥梁工程安全控制教育部重点实验室,湖南长沙410114

出　　处：《桥梁建设》2023年第1期55-62,共8页Bridge Construction

基　　金：国家自然科学基金项目(52108140);湖南省自然科学基金项目(2021JJ40213,2020JJ4310);长沙理工大学桥梁工程安全控制教育部重点实验室开放基金项目(13KB02)。

摘　　要：为研究掺钢纤维无配筋超高性能混凝土(UHPC)矩形梁的抗扭性能,分析钢纤维类型对梁体纯扭受力行为的影响,设计制作4根UHPC矩形梁[包括未掺钢纤维试件1根;掺短圆直、长圆直、端钩钢纤维试件各1根(钢纤维长分别为13,20,13 mm,直径均为0.2 mm,体积掺量均为2%)],并设计1套纯扭加载装置进行试件纯扭试验。基于试验结果,分析各试件在纯扭作用下的扭矩~扭率曲线、开裂和极限扭矩、扭矩~应变曲线、裂缝分布等,并推导UHPC矩形梁的抗扭承载力计算公式,将计算值与试验值进行对比验证。结果表明:掺入钢纤维使UHPC试件由脆性破坏变为延性破坏,且开裂和极限扭矩均有明显提升,最大提升幅度分别为45.6%和100.6%;当体积掺量不变时,钢纤维类型对无配筋UHPC梁开裂扭矩和扭率影响较小,但对极限扭矩和扭率以及裂缝分布有较大影响;掺端钩纤维试件和掺长圆直纤维试件的抗扭承载力和延性均优于掺短圆直纤维试件;掺钢纤维UHPC梁在纯扭作用下的主拉和主压应变显著高于未掺试件,表明钢纤维可以有效“桥联”UHPC基体;试件的抗扭承载力试验值和计算值比值的平均值为0.93,标准差为0.09,说明提出的抗扭承载力计算公式具有良好的精度。建议实际工程中的无筋或少筋UHPC构件采用端钩或长圆直纤维,以改善结构的抗扭延性和裂后承载力。The torsional performance of the steel fiber reinforced UHPC rectangular beams without conventional reinforcement is studied,and the influence of steel fiber patterns on the pure torsional behavior of the beam of such type is analyzed.Four UHPC rectangular beam specimens were prepared for tests,including one with short straight steel fibers,one with long,circular and straight steel fibers,and one with end-hooked steel fibers,the corresponding fiber lengths are 13,20 and 13 mm,respectively,with a diameter of 0.2 mm and mixing content of 2%.A set of loading equipment was designed for the pure torsional performance tests of the specimens.With the test results,multiple items were analyzed,including the torsional moment-torsional rate curve,cracking strength,ultimate torsional moment,torsional moment-strain curve and crack patterns.The expression of the torsional resistance of the UHPC rectangular beam was derived.The calculated results were compared with the test results for verification.It is shown that after adding steel fibers,the damage of UHPC specimen transforms from brittle failure to ductile failure,and the cracking strength and torsional moment are significantly improved,even with a maximum improvement of 45.6%and 100.6%,respectively.When the mixing content keeps constant,the influence of steel fiber types on the cracking torsional moment and torsional rate of the UHPC beam without reinforcement is negligible,but still significant on the ultimate torsional moment and torsional rate.The torsional resistance and ductility of specimens mixed with either the end-hooked steel fibers or the long,circular and straight steel fibers are superior to those of the specimen mixed with short,circular and straight fibers.Compared with the specimen without steel fibers,the UHPC beam with steel fibers has got higher principal tensile and compressive strains under pure torsional forces,indicating that steel fibers can effectively bridge the UHPC matrix.The average ratio of test and calculated torsional resistance of the speci

关 键 词：超高性能混凝土 矩形梁 无配筋 钢纤维 裂缝分布 抗扭性能 抗扭承载力 纯扭试验 

分 类 号：U444[建筑科学—桥梁与隧道工程] U446.1[交通运输工程—道路与铁道工程]