Innovative Design for Sustainable Bridges and Other Structures

可持续桥梁和其他结构的创新设计

• 批准号: RGPIN-2014-04683
• 负责人: ElBadry, Mamdouh
• 金额: $ 1.46万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=650012
• 关键词: Innovative; Design; Sustainable; Bridges; Other

The proposed research aims at providing innovative design for sustainable performance of concrete bridge and building structures. Focus will be placed on two projects:*1) Development of a Hybrid Corrosion-Free Bridge System: An innovative corrosion-free system for short and medium span bridges is proposed. The system consists of precast prestressed concrete truss girders and a cast-in-place or precast deck slab. The girders have top and bottom concrete chords made of glass fibre reinforced polymer (FRP) hollow sections filled with concrete. The chords are connected by precast vertical and diagonal truss members made of concrete-filled GFRP tubes. The vertical members are mainly in compression and connected to the chords using GFRP dowels. The diagonals are in tension and connected to the chords by GFRP double-headed bars. The bottom chord is pretentioned with carbon FRP strands. The FRP hollow sections are produced by filament winding. They and the tubes serve as stay-in-place formwork, confine the concrete in compression, and provide tensile and shear reinforcement. Short GFRP double-headed studs are used in the girders top chords to connect to the deck slab. The girders can be post-tensioned by external CFRP tendons to balance the slab weight and to provide continuity in multi-span bridges. The new system has the advantages of reduced self-weight and enhanced durability. The light weight reduces the load on the supports and allows for longer spans, resulting in reduction in the size of substructure and in the number of supporting piers in multi-span bridges and, hence, reduction in the initial cost. The improved durability reduces the maintenance cost and extends the structure's life span. Computer models will be developed to investigate an optimum design of the truss girder. Such design should result in the lightest girder with best performance. The models will be used to determine the optimum girder depth for different spans and the optimum dimensions of the truss chords, amount of prestressing, size of the web members, and number and size of headed bars needed to connect the diagonals to the chords. Full-scale specimens will be fabricated and tested under static, fatigue, and sustained load in order to verify the optimum design. The long-term objective is to develop guidelines and procedures for design and construction of the new bridge system.*2) Novel Reinforcing Details in Dapped Ends of Precast Girders for Strength and Durability: The ends of precast girders often have reduced depth over short lengths in the form of dapped ends. Girders with dapped ends are frequently used in bridges and parking structures. Because of the reduced depth at the girder ends, the shear stresses are high, and, therefore, design of dapped ends requires special consideration. Dapped ends are typically reinforced with conventional steel closely-spaced stirrups and longitudinal reinforcing bars, which require hooks and bends and even welded plates to ensure sufficient anchorage. Recent research by the applicant has shown that reinforcing dapped ends with single and double headed steel studs eliminates congestion and provides efficient anchorage to concrete without the need for external anchor plates. Bridges and parking structures are exposed to harsh environment in which corrosion of steel is a major source of deterioration. This project aims at investigating the efficiency of reinforcing dapped-end zones with FRP headed bars in lieu of steel studs to achieve higher strength and better durability. Static load and fatigue tests will be conducted on series of dapped-end beams reinforced with FRP headed bars of different layouts. Analytical studies will be carried out to develop guidelines for design of dapped ends reinforced with FRP headed bars.

拟议的研究旨在为混凝土桥梁和建筑结构的可持续性能提供创新设计。重点将放在两个项目上：*1）混合防腐蚀桥梁系统的开发：提出了一种用于中短跨桥梁的创新防腐蚀系统。该系统由预制预应力混凝土桁架梁和现浇或预制楼板组成。梁的顶部和底部混凝土弦杆由玻璃纤维增​​强聚合物（FRP）空心型材制成，并填充混凝土。弦杆由预制的垂直和对角桁架构件连接，该桁架构件由填充混凝土的 GFRP 管制成。垂直构件主要受压，并使用 GFRP 销钉连接到弦杆。对角线处于拉力状态，并通过 GFRP 双头杆连接到弦杆。下弦由碳纤维增强塑料绞线固定。玻璃钢空心型材采用纤维缠绕法生产。它们和管子充当固定模板，将混凝土限制在压缩状态，并提供拉伸和剪切加固。梁上弦使用短 GFRP 双头螺柱连接至楼面板。梁可以通过外部 CFRP 筋进行后张紧，以平衡板重量并提供多跨桥梁的连续性。新系统具有减轻自重和增强耐用性的优点。重量轻，减少了支撑上的负载，并允许更长的跨度，从而减少了下部结构的尺寸和多跨桥梁中支撑桥墩的数量，从而降低了初始成本。耐久性的提高降低了维护成本并延长了结构的使用寿命。将开发计算机模型来研究桁架梁的优化设计。这样的设计应该会产生最轻的梁和最好的性能。这些模型将用于确定不同跨度的最佳梁深度以及桁架弦杆的最佳尺寸、预应力量、腹杆尺寸以及将对角线连接到弦杆所需的带头钢筋的数量和尺寸。将在静态、疲劳和持续负载下制造和测试全尺寸样本，以验证最佳设计。长期目标是为新桥梁系统的设计和施工制定指南和程序。*2) 预制梁斑端的新颖加固细节，以提高强度和耐用性：预制梁端部的深度通常在较短的长度内减小以斑点末端的形式。末端有斑点的大梁经常用于桥梁和停车场。由于梁端部的深度减小，剪应力很高，因此，补缀端部的设计需要特别考虑。缺口端通常用传统的紧密间隔的钢箍筋和纵向钢筋进行加固，这需要钩子和弯头，甚至焊接板来确保足够的锚固。申请人最近的研究表明，用单头和双头钢螺柱加固带状端部消除了堵塞，并提供了对混凝土的有效锚固，而不需要外部锚板。桥梁和停车场结构暴露在恶劣的环境中，其中钢材的腐蚀是劣化的主要原因。该项目旨在研究用 FRP 带头钢筋代替钢螺柱加固端部区域的效率，以实现更高的强度和更好的耐用性。静载和疲劳试验将对一系列不同布局的 FRP 头筋加固的端部梁进行。将进行分析研究，以制定用 FRP 头钢筋加固的端部设计指南。