体外预应力UHPC梁预应力筋极限应力增量理论研究  

Research on Ultimate Stress Increment of Prestressing Tendons in Externally-Prestressed UHPC Girder

作　　者：邓继华 李冬亮 颜凌志 周亚栋 DENG Jihua;LI Dongliang;YAN Lingzhi;ZHOU Yadong(National Key Laboratory of Bridge Intelligent and Green Construction,Wuhan 430034,China;School of Civil Engineering,Changsha University of Science and Technology,Changsha 410114,China;China Railway Bridge Science Research Institute,Ltd.,Wuhan 430034,China)

机构地区：[1]桥梁智能与绿色建造全国重点实验室,湖北武汉430034 [2]长沙理工大学土木工程学院,湖南长沙410114 [3]中铁大桥科学研究院有限公司,湖北武汉430034

出　　处：《桥梁建设》2023年第4期55-61,共7页Bridge Construction

基　　金：国家自然科学基金项目(52278142);湖南省教育厅重点科学研究资助项目(21A0187);桥梁结构健康与安全国家重点实验室开放课题(BHSKL21-06-GF)。

摘　　要：为了解UHPC抗拉性能对体外预应力UHPC梁的影响,开展体外预应力UHPC梁受力至破坏全过程非线性分析,建立体外预应力UHPC梁预应力筋极限应力的计算方法和适用公式。首先在假定通长范围内体外预应力筋为常应变受力特性的前提下,采用迭代法精确求解体外预应力筋应变增量;然后编制体外预应力梁全过程非线性分析程序,并进行程序验证;最后参照国内外规范提出适用于体外预应力UHPC梁的预应力筋极限应力计算公式,以21根模拟体外预应力UHPC梁为研究对象,对比公式和非线性程序计算值。结果表明:体外预应力UHPC梁全过程非线性分析方法在计入UHPC抗拉性能的基础上精确考虑了体外预应力筋的受力特点,方法正确;考虑UHPC抗拉强度前、后计算所得的体外预应力筋极限应力增量相差2%~5%,说明UHPC的抗拉强度对体外预应力筋极限应力增量有一定影响;提出的公式具有一定的参考价值。This paper presents the lifetime and failure process of an UHPC(ultra-high performance concrete)girder as well as the findings of non-linear analysis to figure out the methods and equations to calculate the ultimate stresses of the prestressing tendons in the externally-prestressed UHPC girder,and to examine the effect of tensile strength of UHPC on the externally-prestressed UHPC girder.First,assuming that the external prestressing tendons exhibit constant stress-strain response over their through-lengths,the ultimate stress of the external prestressing tendons are computed by iterative method.Then,a lifetime non-linear analysis program of the externally-prestressed girder is compiled and verified.At last,equations to calculate the ultimate stress increment of the externally-prestressed UHPC girder are proposed,referencing the AASHTO-2010 and China′s Specifications for Strengthening Design of Highway Bridges(JTG/T J22-2008).An UHPC girder equipped with 21 external prestressing tendons is used for a case study.The calculations of the equations are compared with those of non-linear analysis.It is shown that the non-linear analysis method takes into account the tensile strength of the UHPC as well as the load bearing behaviors of the external prestressing tendons,proving the efficiency of the method.The difference of ultimate stress increment of the external prestressing tendons before and after the consideration of the tensile strength of UHPC is about 2%to 5%,meaning that the tensile strength of UHPC is significant to the ultimate stress increment of the external prestressing tendons,and the equations can be used as alternatives for calculation.

关 键 词：桥梁工程 UHPC梁 体外预应力筋 应变增量 极限应力增量 非线性分析 

分 类 号：U448.21[建筑科学—桥梁与隧道工程] U448.35[交通运输工程—道路与铁道工程]