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降低預應力混凝土橋墩的地震破壞

2017年12月04日 15:01  點擊:[]

報告題目:

降低預應力混凝土橋墩的地震破壞

Lowering Seismic Damage to Precast Concrete Piers

 

 

報告人:

楊燦璨,博士,紐約州立大學布法羅分校土木與環境工程學院。

 

報告時間:12月25日(周一),上午10:30~12:00

 

報告地點:綜合試驗三號樓五樓會議室

 

報告簡介:

目前,快速建造橋梁施工體系中的預應力混凝土構件沒有在多震區域充分投入使用,研究表明通過對連接處的抗震設計和體系的優化可以改善這一現狀。本次報告將要介紹三種預制后張式預應力混凝土橋墩以及提高其抗震性能的方法研究:搖擺式自回復體系,模擬現澆式體系ag环亚娱乐集团,和混合體系ag环亚娱乐集团。研究目的是降低預制橋墩在地震災害下的破壞,從而減輕修復工作ag环亚娱乐集团,以及最小化橋梁抗震功能的損失。

在搖擺式自回復體系橋墩中,預制節段依靠脫黏后張預應力鋼筋拼裝組合在一起。該體系具有避免塑性鉸破壞,并且在地震之后恢復到震前位置的能力。在模擬現澆式體系中,墩柱以插插座的方式嵌入墩底基礎中ag环亚娱乐集团?;旌象w系則是在橋墩的上部分采用搖擺自回復體系,而下部分與基礎的連接則是采用模擬現澆的方式。  在此研究中ag环亚娱乐集团,以上提到的每種體系都將采用高性能材料來控制地震破壞。

理論分析和大比例縮尺實驗表明:對于搖擺式自回復體系,通過在破壞集中區域采用高性能混凝土,搖擺造成的壓碎性破壞以及該區域對箍筋的需求將大幅度降低。此外ag环亚娱乐集团,該研究提出了對地震造成的預應力損失的預估公式,并通過與大比例尺實驗結果比較對其準確性進行了驗證ag环亚娱乐集团。該研究建立并驗證了一個橋墩整體的滯回反應的分析模型ag环亚娱乐集团,此模型用于理解分析通過節段滑移而得到的耗能的加強ag环亚娱乐集团。有限元分析結果表明在模擬現澆式體系和混合體系中使用高性能混凝土也將減輕塑性鉸區的破壞。對于混合體系,本次報告會介紹闡述簡化的理論設計模型以及通過材料試驗對高性能混凝土材料模型的定義,  以及大比例尺試件材料的選取?;旌象w系的設計旨在于耗能ag环亚娱乐集团,自回復能力以及破壞情況中尋求平衡從而優化抗震性能。

 

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.

 

報告人簡介:

楊燦璨現就讀于紐約州立大學布法羅分校土木與環境工程學院博士三年級。她在重慶大學取得學士學位,在紐約州立大學布法羅分校取得碩士學位。她的研究興趣包括:適用于快速建造方法的創新式可持續橋梁系統的建立以及抗震性能的優化;  大比例縮尺實驗;在橋梁設計中采用高性能材料來提高抗震性能ag环亚娱乐集团;橋梁基于性能的設計方法;自回復結構的設計要素。

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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