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降低预应力混凝土桥墩的地震破坏

2017年12月04日 15:01  点击:[]

报告题目:

降低预应力混凝土桥墩的地震破坏

Lowering Seismic Damage to Precast Concrete Piers

 

 

报告人:

杨灿璨,博士,纽约州立大学布法罗分校土木与环境工程学院。

 

报告时间:12月25日(周一),上午10:30~12:00

 

报告地点:综合试验三号楼五楼会议室

 

报告简介:

目前,快速建造桥梁施工体系中的预应力混凝土构件没有在多震区域充分投入使用,研究表明通过对连接处的抗震设计和体系的优化可以改善这一现状。本次报告将要介绍三种预制后张式预应力混凝土桥墩以及提高其抗震性能的方法研究:摇摆式自回复体系,模拟现浇式体系,和混合体系。研究目的是降低预制桥墩在地震灾害下的破坏,从而减轻修复工作,以及最小化桥梁抗震功能的损失。

在摇摆式自回复体系桥墩中,预制节段依靠脱黏后张预应力钢筋拼装组合在一起。该体系具有避免塑性铰破坏,并且在地震之后恢复到震前位置的能力。在模拟现浇式体系中,墩柱以插插座的方式嵌入墩底基础中。混合体系则是在桥墩的上部分采用摇摆自回复体系,而下部分与基础的连接则是采用模拟现浇的方式。  在此研究中,以上提到的每种体系都将采用高性能材料来控制地震破坏。

理论分析和大比例缩尺实验表明:对于摇摆式自回复体系,通过在破坏集中区域采用高性能混凝土,摇摆造成的压碎性破坏以及该区域对箍筋的需求将大幅度降低。此外,该研究提出了对地震造成的预应力损失的预估公式,并通过与大比例尺实验结果比较对其准确性进行了验证。该研究建立并验证了一个桥墩整体的滞回反应的分析模型,此模型用于理解分析通过节段滑移而得到的耗能的加强。有限元分析结果表明在模拟现浇式体系和混合体系中使用高性能混凝土也将减轻塑性铰区的破坏。对于混合体系,本次报告会介绍阐述简化的理论设计模型以及通过材料试验对高性能混凝土材料模型的定义,  以及大比例尺试件材料的选取。混合体系的设计旨在于耗能,自回复能力以及破坏情况中寻求平衡从而优化抗震性能。

 

Precast  concrete elements for accelerated bridge construction are under-utilized in  seismic regions. In these regions, connections and systems developed  specifically for seismic performance can help deploy accelerated construction.  This presentation will introduce three precast, post-tensioned  concrete, bridge pier systems designed for enhanced seismic performance:  non-emulative of cast-in-place concrete, emulative of cast-in-place concrete,  and a hybrid system. All systems aim to lower damage in order to minimize repair  costs and loss of functionality for infrastructure resiliency against seismic  hazards.

The  precast segments in non-emulative piers are assembled together using unbonded  post-tension strands to prevent plastic hinging can self-center (rock). In the  emulative pier, the column is connected to the foundation by a socket type  joint. In the hybrid pier, both rocking non-emulative and emulative joints are  used. Each system employs advanced materials to control seismic  damage.

Analyses and testing showed that, for non-emulative piers,  compression damage due to rocking and need for confinement can be eliminated  using Ultra-High Performance Concrete (UHPC) in strategic regions. A method to  predict seismic post-tension loss was proposed. A mechanics based analytical  model was created and used to understand the enhanced energy dissipation by  intentionally allowing segmental shear-slip. Finite element analysis results  showed that incorporating UHPC can also alleviate plastic hinging damage in  emulative and hybrid systems. For the hybrid pier, the presentation will cover a  simplified pushover analytical model and material properties of fiber reinforced  concrete, UHPC, were selected through material scale testing. Analytical results  show that the hybrid pier can provide a balance between lowering damage through  self-centering and UHPC, and energy dissipation.

 

报告人简介:

杨灿璨现就读于纽约州立大学布法罗分校土木与环境工程学院博士三年级。她在重庆大学取得学士学位,在纽约州立大学布法罗分校取得硕士学位。她的研究兴趣包括:适用于快速建造方法的创新式可持续桥梁系统的建立以及抗震性能的优化;  大比例缩尺实验;在桥梁设计中采用高性能材料来提高抗震性能;桥梁基于性能的设计方法;自回复结构的设计要素。

Cancan Yang is a Ph.D. Candidate in the Department of Civil,  Structural, and Environmental Engineering at University at Buffalo, the State  University of New York. She obtained a bachelor’s degree from Chongqing  University and a master’s degree from University at Buffalo. Her research  interests include development and large-scale testing of innovative and  sustainable bridge systems for accelerated construction and optimum seismic  performance, integration of advanced concrete materials in bridge design for  seismic resiliency, performance-based seismic design and assessment of bridges,  and investigation of design considerations for self-centering  structures.

 


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