底部采用延性纤维混凝土的预应力节段拼装桥墩抗震性能研究

A new post-tensioned segmental bridge pier system is proposed by using ductile fiber concrete in the reasonable bottom region. The proposed system is expected to have stable energy dissipation capacity and high damage tolerance in a controllable deformation range. The seismic performance of the bridge pier is studied thoroughly and the corresponding seismic design method is presented as well. The detailed research is carried out as follows: Firstly, based on the existing research results, a new mix proportion of ductile fiber concrete is developed to better meet the requirement of improving the seismic performance of the post-tensioned segmental bridge columns. The corresponding mechanical analysis model and the calculation model of the newly proposed material are established. Secondly, the seismic performance of the common post-tensioned segmental bridge piers and the corresponding ductility enhanced piers is studied. The differences of failure characteristics and energy dissipation performance between the two types of piers are analyzed and discussed ulteriorly. Thirdly, based on the computer simulation and parameter optimization analysis, the reasonable height of the ductile enhanced region in the bridge pier is studied. Meanwhile, the requirement of performance matching of the ductility enhanced region and the upper segment is considered and the interface treatment as well as the related construction measures is studied. At last, based on the studies mentioned above, the displacement-based structural seismic design and construction methods of the proposed bridge pier system are presented. The research of this project will provide theoretical and technical supports for the application of post-tensioned segmental bridge piers in our country.

为了提高预应力节段拼装桥墩的抗震性能，完善相应的抗震设计方法，本项目拟采用理论分析和模型试验相结合的方法，研究底部合理范围采用延性纤维混凝土、变形性能可控的预应力节段拼装桥墩抗震性能及其相应的抗震设计方法。主要内容有：结合已有研究成果，优化材料配合比，研发适合提高预应力节段拼装桥墩抗震性能的新型延性纤维混凝土，建立相应的力学分析和计算模型；研究此类常规桥墩和底部采用新型延性纤维混凝土桥墩的抗震性能，分析两类桥墩破坏特征和耗能性能的差异，探讨其抗震性能的一般规律；采用计算机模拟和参数优化分析，研究预应力节段拼装桥墩性能可控延性增强区的合理高度、增强区与上部性能的优化匹配、界面处理方法及其构造措施等，提出基于位移的工程优化抗震设计理论和构造方法，为预应力节段拼装桥墩在我国实际工程中推广应用提供理论和技术支撑。

预应力节段拼装桥墩能够满足最严苛的运输条件、工期要求、保通要求和环保要求，且具有震后残余位移小、易于修复等特殊优点在道路桥梁建设中具有广阔的应用前景。但是，此类桥墩在地震作用下破坏主要集中于墩底节段，且塑性耗能能力较弱，用于抗震不经济。为了提高预应力节段拼装桥墩的抗震性能，完善相应的抗震设计方法，本项目采用理论分析和模型试验相结合的方法，研究底部合理范围采用延性纤维混凝土、变形性能可控的预应力节段拼装桥墩抗震性能及其相应的抗震设计方法。主要内容有：结合已有研究成果，优化材料配合比，研发适合提高预应力节段拼装桥墩抗震性能的新型延性纤维混凝土，建立了相应的力学分析和计算模型；基于拟静力试验，研究了此类常规桥墩和底部采用新型延性纤维混凝土桥墩的抗震性能，分析了两类桥墩破坏特征和耗能性能的差异，探讨了其抗震性能的一般规律；采用计算机模拟和参数优化分析，研究了预应力节段拼装桥墩性能可控延性增强区的合理高度、增强区与上部性能的优化匹配及其构造措施等，提出了基于位移的工程抗震设计理论和构造方法，为预应力节段拼装桥墩在我国实际工程中推广应用提供了理论和技术支撑。