基于变形能力的钢筋混凝土桥墩约束箍筋用量评价

Evaluation of Amounts of Confining Stirrups Used for RC Bridge Columns Based on Deformation Capacity

针对地震作用下钢筋混凝土桥墩的变形能力要求,研究桥墩潜在塑性铰区约束箍筋的用量问题。借助美国PEER柱抗震性能试验数据库,整理了35根弯剪破坏墩柱的拟静力试验数据,通过统计分析评价我国桥梁抗震设计原《公路工程抗震设计规范》(JTJ 004-89)和现行《公路桥梁抗震设计细则》(JTG/T B02-01-2008)中最低约束箍筋用量对保证桥墩变形能力的可靠性,并与美国、欧洲主要桥梁抗震设计规范进行对比,之后建立了具有85%保证率的弯剪破坏桥墩极限位移角计算公式。研究结果表明:以2%桥墩极限位移角为评价目标,现行《公路桥梁抗震设计细则》满足桥墩变形能力要求;而以3%桥墩极限位移角为评价目标,该规范配箍要求略偏于不安全,在高地震危险区桥墩抗震设计时应予以注意。

In accordance with the required deformation capacity for reinforced concrete （RC） bridge columns under the seismic action, the amounts of the confining stirrups used for the poten- tial plastic hinge zones of the columns were studied. From the PEER （the Pacific Earthquake En- gineering Research Center, USA） database for seismic performance testing of the columns, the quasi-static test data of 35 columns failing in flexure-shear were collected and sorted and through the statistical analysis, the reliability of the minimum amounts of the confining stirrups that could guarantee the deformation capacity of the columns as provided in the former code for the seismic design of bridges in China, the Specifications of Earthquake Resistant Design for Highway En- gineering （JTJ 004-89） and in the current code, the Guidelines for Seismic Design of Highway Bridges （JTG/T B02-01-2008） was evaluated. The provisions of the minimum amounts of the stirrups in the above codes were then compared to those in the main bridge seismic design specifi- cations of the USA and Europe and finallv the formula of the ultimate drift angle having 85 % as-surance ratio for the columns {ailing in flexure-shear was established. The results of the study show that by taking the 20//00 ultimate drift angle of a column as the evaluation target, the provi-sions in the current Chinese cod column while by taking the 3 of the confining stirrups in the c in the high risk seismic regions, e JTG/T B02-01-20 ultimate drift angle ode are somewhat n 08 can s as th ot saf due attention should be pa atisfy the deformation capacity of the arget, the provisions on the amounts For the seismic design of the columns id.