GFRP板材粘贴修复正交异性钢桥板疲劳裂缝的理论与试验研究

Nowadays, fatigue cracks on the orthotropic steel decks significantly threaten the safety and service life of steel bridges, which have attracted great attention in the bridge engineering field. However, there has been no reliable rehabilitation theory or renovation method for these cracked steel decks by now. In this project, the glass fiber reinforced polymer (GFRP), which owns the high strength to weight ratio and good durability, is employed for repairing the cracked orthotropic steel decks. The aim of the project is to reveal more understanding on the mechanical behavior, failure mode and fatigue performance of renovated GFRP-steel composite deck, which is also the urgent issue needs to be addressed for the investigation of steel deck rehabilitation. Herein, theory analysis, experimental investigation and numerical modelling are employed to study the material properties of GFRP laminates and structural adhesive, the constructional method of adhesive connections between GFRP laminates and cracked steel decks as well as the comparison of stress distribution and fatigue performance of orthotropic steel decks before and after rehabilitation. Finally, the effective and reliable rehabilitation theory for cracked steel decks is addressed and the design method is proposed. By gluing a new layer of GFRP laminates to the old steel deck, the steel deck is rehabilitated to be a composite slab of GFRP and steel plates working together to bear the load. It is an innovative approach in the field of bridge renovation using high-performance composite materials, which is of significance for theory development and practical application of the rehabilitation of cracked orthotropic steel decks.

正交异性钢桥板的疲劳裂缝是影响桥梁寿命的重要因素，已引起桥梁工程领域的广泛关注，然而工程界尚无对其进行修复的成熟理论与方法。本课题提出采用轻质高强耐久性好的GFRP板材修复正交异性桥板疲劳裂缝的方法，以期延长桥梁的疲劳寿命。明确加固后GFRP组合钢桥板的力学性能、破坏演化机理及其疲劳行为，是确定该加固方法对疲劳裂缝控制效率的关键，也是探索正交异性钢桥板修复理论急需解决的问题。本项目拟针对GFRP板材和结构胶的材性、GFRP板粘贴的施工方法、加固前后正交异性桥板的应力分布和疲劳寿命，展开系统的理论分析、试验研究和数值模拟，探索加固后GFRP组合钢桥板的设计方法，提出经济合理的开裂正交异性钢桥板的修复理论。本课题开拓高性能复合材料用于修复桥梁的新思路，将独立承载的正交异性钢桥板通过加固转化为协同工作的GFRP组合钢桥板，延长其疲劳寿命，为老桥的革新改造提供理论支撑，具有重大的理论和实际意义。

正交异形钢桥面板的疲劳裂缝大都发生在加劲肋与桥面板焊接接头处，严重威胁着桥梁的安全。目前，对这种疲劳裂缝的修复仍还没有系统可靠的方法，所以迫切需要相关理论的建立和实验数据的积累。本研究提出采用FRP板粘贴法修复正交异性钢桥板疲劳裂缝，主要研究内容包括：1）FRP板材受弯与受剪力学性能（包括弹性模量、强度和极限应变等）及其层间断裂机理研究；2）FRP板材在湿热环境下力学性能的退化研究及水分侵入过程研究及有限元模拟；3) 受弯剪共同作用的FRP-钢胶接节点在常温常态和湿热环境中的力学性能、破坏模式和强度准则；4) FRP板材粘贴加固正交异性桥板的有限元参数分析研究； 5) 加固前后正交异性桥板足尺试验研究。本项目取得的重要研究结果包括：1）采用称重法确定了FRP板材的吸水速率和吸水饱和度，并建立有限元稳态模型模拟FRP板材水分侵入全过程，模型得到试验验证，可用于预测较长服役期内大尺寸FRP结构的吸水量分布；2）通过设置三点弯曲试验中不同的支撑间距，研究FRP板材的抗弯抗剪刚度和强度受湿热环境的影响，结果表明湿热环境对刚度和强度的影响都较大，一次吸水放水循环造成FRP材料产生不可恢复的力学性能损失，实际工程应用中应充分考虑。建立了温湿度—力学耦合模型，实现了基于不同时段不同区域吸水浓度域函数的有限元力学分析。3）设计制造了可提供拉剪组合受力加载模式的试验装置，研究FRP-钢胶结节点在复杂受力状态下的力学性能，湿热老化环境大大降低了节点的整体刚度，但对拉剪组合应力作用下的节点强度影响较小，最终确定了胶结节点的强度准则。4）通过对FRP板粘贴修复钢桥板模型的有限元参数分析，得到了FRP板材各参数对加固效率的影响规律，确定了最优加固方案。5）通过截段模型试验，比较加固前后钢桥板的力学性能及疲劳寿命。本研究不仅为考虑长期性能的FRP组合结构设计提供了必要的设计参数和材料本构关系，为钢桥的高效加固提供数据基础，也为未来FRP结构规范的编写及修订提供必要依据。