| 配筋UHPC矩形梁抗扭承载性能试验与计算方法 |
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| 引用本文： | 李传习,周佳乐,柯璐,方昌乐,施宇,潘仁胜.配筋UHPC矩形梁抗扭承载性能试验与计算方法[J].中国公路学报,2021,34(8):118-131. |
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| 作者姓名： | 李传习 周佳乐 柯璐 方昌乐 施宇 潘仁胜 |
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| 作者单位： | 1. 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;2. 长沙理工大学 土木工程学院, 湖南 长沙 410114;3. 广西大学 土木建筑工程学院, 广西 南宁 530004 |
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| 基金项目： | 国家自然科学基金项目（51778069，51708047，51808055）；湖南省自然科学基金项目（2019JJ50670）；湖南省创新基金项目（CX20190656） |
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| 摘 要： | 针对配筋超高性能混凝土（UHPC）构件的抗扭性能研究严重不足的状况，进行10个不同配筋率UHPC矩形梁的纯扭试验。研究参数主要包括钢纤维掺量、纵筋配筋率和箍筋配筋率。观察或测试试件的扭转破坏过程及形态，获得裂缝开展及分布情况、失效模式、扭矩-扭率曲线、扭矩-UHPC应变曲线、扭矩-钢筋应变曲线、开裂扭矩及极限扭矩等数据，分析不同参数对其扭转性能的影响规律及其主要机理。研究结果表明：扭矩不大于无筋UHPC试件极限扭矩时，配筋构件抗扭刚度小于无筋构件；配筋及无筋试件的纯扭破坏均表现为多条主裂缝贯通，且裂缝呈空间螺旋状分布；无配筋试件形成少量斜裂缝，极限扭率较小，破坏过程迅速；配筋试件形成细且密的斜裂缝、极限扭率较大、延性更好；根据实测的极限扭矩扭率增幅情况，以及纵、箍筋屈服情况，受扭的UHPC配筋试件可分为少筋Ⅰ类构件（含无筋构件）、少筋Ⅱ类构件、适筋构件、部分超筋构件、超筋构件；钢纤维改善了UHPC抗拉特征，使得主裂缝开裂角度（裂缝与试件轴线的夹角）增加；钢纤维掺量由2.5%增加到3.5%，试件开裂扭矩和极限扭矩分别提高了23.2%和20.9%。在试验的基础上，根据扭转试件即将开裂时实测的拉压应力状态以及二维应力状态下的强度准则，得到UHPC构件开裂扭矩系数值；最后，根据试验结果得到了UHPC极限扭矩计算公式的截面抗扭系数。
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| 关 键 词： | 桥梁工程 纯扭性能 试验研究 配筋超高性能混凝土矩形梁 开裂扭矩 极限扭矩 |
| 收稿时间： | 2020-07-14 |
Experimental Investigation and Calculation of the Torsional Capacity of Reinforced UHPC Rectangle Beams |
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| LI Chuan-xi,ZHOU Jia-le,KE Lu,FANG Chang-le,SHI Yu,PAN Ren-sheng.Experimental Investigation and Calculation of the Torsional Capacity of Reinforced UHPC Rectangle Beams[J].China Journal of Highway and Transport,2021,34(8):118-131. |
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| Authors: | LI Chuan-xi ZHOU Jia-le KE Lu FANG Chang-le SHI Yu PAN Ren-sheng |
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| Affiliation: | 1. Key Laboratory of Safety Control of Bridge Engineering Ministry of Education, Changsha University of Science and Technology, Changsha 410114, Hunan, China;2. College of Civil Engineering, Changsha University of Science and Technology, Changsha 410114, Hunan, China;3. College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, Guangxi, China |
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| Abstract: | Owing to the insufficient research on the pure-torsional performance of reinforced ultra-high-performance concrete (UHPC) components, a total of ten rectangular beams were tested under pure torsion. The parameters of the specimens considered for the investigation included the volume fraction of steel fibers, stirrup reinforcement ratio, and longitudinal reinforcement ratio. By observing the torsional failure process, the crack development and distribution modes, failure modes, torque-torsion curves, torsion-UHPC strain curves, torsion-steel bar strain curves, cracking torsional strength, and ultimate torsional strength were presented. The influence of the above design parameters on the torsional behavior was analyzed. The results indicate that the torsional stiffness of the reinforced specimens with a low ultimate torque is less than that of the unreinforced specimens. Space spiral main cracks were observed in the unreinforced and reinforced specimens. A few slender diagonal cracks were observed in the unreinforced specimen, and the unreinforced specimens destroyed rapidly with insignificant deformation. However, several slender and dense diagonal cracks were observed in the reinforced specimen, which exhibited a high ultimate torque and good ductility. The reinforced specimens can be divided into type Ⅰ rare-reinforced specimens, type Ⅱ rare-reinforced specimens, suitable reinforced specimens, partial over-reinforced specimens, and over-reinforced specimens, according to the increment in ultimate torque or twist and the stress state of the steel bars. The cracking angle (the angle between the crack and specimen axis) increases owing to the improvement in tensile characteristics caused by the effect of steel fibers. With an increase in the steel fiber volume fraction from 2.5% to 3.5%, the cracking torque and ultimate torque increased by 23.2% and 20.9%, respectively. Based on the experimental results, the coefficient of cracking torque was proposed by considering the measured UHPC stresses and failure criterion under the biaxial stress state. Finally, the calculation method for the ultimate torsional capacity was modified via the sectional torsional coefficient of the concrete. |
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| Keywords: | bridge engineering pure-torsional behavior experimental investigation reinforced ultra-high performance concrete rectangle beam cracking torque ultimate torque |
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