预应力UHPC梁抗剪承载力计算方法  

Calculation method for shear bearing capacity of prestressed UHPC beam

作　　者：马熙伦 陈宝春[2] 韦建刚 林上顺 黄卿维[2] 苏家战 陈逸聪 吴志鸿 MA Xi-lun;CHEN Bao-chun;WEI Jian-gang;LIN Shang-shun;HUANG Qing-wei;SU Jia-zhan;CHEN Yi-cong;WU Zhi-hong(School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China;College of Civil Engineering, Fuzhou University, Fuzhou 350108, China;CSCEC Strait Construction and Development Co., Ltd., Fuzhou 350015, China;School of Civil Engineering, Fujian University of Technology, Fuzhou 350118, China)

机构地区：[1]宁夏大学土木与水利工程学院,宁夏银川750021 [2]福州大学土木工程学院,福建福州350108 [3]中建海峡建设发展有限公司,福建福州350015 [4]福建工程学院土木工程学院,福建福州350118

出　　处：《广西大学学报（自然科学版）》2020年第5期986-995,共10页Journal of Guangxi University（Natural Science Edition）

基　　金：国家重点研发计划项目(2018YFC0705405)。

摘　　要：为了研究预应力超高性能混凝土(UHPC)梁的抗剪性能,进行了预应力UHPC梁的抗剪性能试验,以预应力值、截面形式为主要参数,分析了试验梁的荷载—挠度曲线、裂缝发展形态、预应力筋应力的变化、混凝土应变、抗剪承载力和破坏模式。试验结果表明:预应力UHPC梁的抗剪受力过程可分为弹性、带裂缝工作和裂缝快速发展三个阶段。试验梁的受力符合平截面假定。试验梁剪跨段中部位置主拉应变及主压应变倾角值最大。试验梁均先出现受剪斜裂缝,后出现受弯竖向裂缝,后者裂缝对梁的抗弯刚度削弱较前者明显。试验梁的破坏属于剪压破坏。对比表明,预应力增加了40%,极限荷载提高了14.3%,表明预应力能明显提高UHPC梁的抗剪承载力。多了翼缘部分的箱形梁,极限荷载比矩形梁提高了18.0%,说明翼缘对抗剪承载力有贡献。基于桁架—拱模型,提出了考虑预应力和截面翼缘作用的预应力UHPC梁抗剪承载力计算方法,计算结果具有较高的计算精度,与本文及他人试验结果比值的均值为1.008,标准差为0.118,相关性系数为0.117。To study the shear performance of prestressed ultra high performance concrete(UHPC)beam,the shear-resistant characteristics of prestressed UHPC beams were tested,in which the prestressed value and section form were taken as the main parameters.The load-deflection curve,cracking pattern,prestressed tendon stress,concrete strain,shear bearing capacity and failure mode of the specimens were analyzed.It is demonstrated that the loading process of prestressed UHPC beam can be divided into three stages:elasticity,working with crack,and crack rapid development stage.The test beams conform to the assumption of plane section.The main tensile strain and the main compressive strain inclination in the middle of shear span were the maximum.The shear cracks appeared first and then the flexural cracks,the latter weakened the flexural stiffness significantly.The specimen lost bearing capacity due to shear compression failure.For the specimen with an increased prestress of 40%,its ultimate bearing capacity increased by 14.3%,which indicates that the prestress can enhance the shear capacity significantly.For specimen with box section which has addition area of the flange,the ultimate bearing capacity increased by 18%,which indicated that the flange has contribution to the shear capacity.Based on the truss-arch model,a calculation method for shear bearing capacity of prestressed UHPC beam is proposed,in which the contribution of prestress and flange are taken into account.The average ratio of the calculated results by the proposed method to the test results in this paper and by others is 1.008,with a standard deviation of 0.118 and correlation coefficient of 0.117,which indicates that the calculation method presented in this paper has good precision.

关 键 词：桥梁工程 超高性能混凝土 预应力梁 翼缘 抗剪承载力 桁架—拱模型 

分 类 号：U442.5[建筑科学—桥梁与隧道工程]