考虑二次受力的UHPC加固RC墩偏压极限承载力  

ULTIMATE LOAD CAPACITY OF UHPC STRENGTHENED RC PIER UNDER ECCENTRIC COMPRESSION CONSIDERING SECONDARY LOAD

作　　者：夏樟华[1] 王明鎏 林上顺 林龙镁 黎雅乐 XIA Zhang-hua;WANG Ming-liu;LIN Shang-shun;LIN Long-mei;LI Ya-le(School of Civil Engineering,Fuzhou University,Fuzhou,Fujian 350108,China;Fujian Provincial Key Laboratory of Advanced Technology and Information in Civil Engineering(Fujian University of Technology),Fuzhou,Fujian 350118,China;Department of Building Engineering,Jiangsu Open University,Nanjing,Jiangsu 210036,China)

机构地区：[1]福州大学土木工程学院,福建福州350108 [2]福建省土木工程新技术与信息化重点试验室(福建工程学院),福建福州350118 [3]江苏开放大学建筑工程学院,江苏南京210036

出　　处：《工程力学》2024年第7期212-225,共14页Engineering Mechanics

基　　金：国家自然科学基金项目(52008187);福建省自然科学基金项目(2020J1477);福建省建设科技项目(2022K223,224)。

摘　　要：为揭示考虑二次受力UHPC加固桥墩偏压受力的损伤机理和极限状态,设计制作了UHPC加固RC墩和未加固墩构件,并进行了相应的试验研究和理论分析,并与未加固墩进行了比较。开展了考虑二次受力的UHPC增大截面法加固RC桥墩的小偏压试验,研究了不同初始受力条件下加固墩的破坏模式和极限承载力。结合有限元模型讨论了UHPC抗压强度、加固层的厚度和配筋率对极限承载力的影响。根据极限状态下的受力特性和平衡关系,推导了UHPC加固RC墩偏压极限承载力计算公式。结果表明:UHPC搭配钢筋网加固墩小偏压承载力与未加固墩相比,提升幅度达到了183%以上。UHPC强度对试件极限承载力的影响较大,UHPC厚度增大对加固试件承载力提高也较明显,加固层配筋率对构件承载力的提高影响较小。初始荷载的增大会降低原墩的混凝土利用率,降低加固墩的极限承载力。所提出考虑二次受力公式的计算承载力与实测值误差在3%之内,与有限元计算值误差在8%之内,具有较高的计算精度。研究结果可以为UHPC加固RC墩偏压承载力计算提供理论依据。To reveal the damage mechanism and limit state of UHPC strengthened piers under eccentric compression with secondary stress considered,the UHPC strengthened RC piers were designed and fabricated,and the corresponding experimental study and theoretical analysis were conducted and compared with un-strengthened RC piers.The small eccentric load tests of UHPC strengthened RC piers with section enlargement method considering secondary stress were carried out,and the failure mode and ultimate load capacity of the strengthened piers with different initial stress were studied.Finite element models of strengthened columns were established,and the influence of UHPC strength,UHPC thickness and longitudinal reinforcement ratio on the ultimate load capacity was discussed by employing the finite element model.Based on the mechanical characteristics and equilibrium relations in limit state,the formula for calculating the ultimate load capacity of RC piers strengthened with UHPC was derived.The test results show that the load capacity of UHPC strengthened RC piers with reinforcement mesh is 183%larger than that of the un-strengthened pier under small eccentric load.The ultimate load capacity of the strengthened piers increases with the UHPC strength.The UHPC thickness has an obvious effect on the load capacity of the strengthened specimens,while the longitudinal reinforcement ratio has small effect on the load capacity.The increase of initial load will reduce the concrete utilization of the original piers,as well as the load capacity of the strengthened piers.The calculated load capacity of the proposed formula considering the secondary force has an error of less than 3%compared with the measured value,and less than 8%compared with the finite element calculation value,showing a relatively high calculation accuracy.The research results can provide a theoretical basis for the calculation of load capacity of RC piers strengthened with UHPC under eccentric compression.

关 键 词：桥墩 UHPC加固 二次受力 偏压 极限承载力 

分 类 号：TU375.3[建筑科学—结构工程]