波纹钢管-UHPC组合的新型桥梁防船撞结构性能及设计方法研究

Protection structures are generally employed to decrease or avoid the risks that the catastrophic accidents of vessel-bridge collisions happen. Thus, their performances and stability are of great importance, related to the safety of structure, property and life. However, the conventional protections (particularly for the steel fender widely used in China) have lots of limitations, e.g., low energy absorption efficiency and stability. Furthermore, no design specifications can be available to design these protection structures and limited tests were conducted to address their real performance under vessel collisions. For these purposes, this project proposes a innovative protection structure composed of corrugated steel tube and ultra-high performance concrete (UHPC) panel (denoted by steel-UHPC fender). In the proposed protection structure, ultra-high performance concrete with excellent anti-impact property is used in the panel that directly contacts with the aberrant vessels. The corrugated steel tube with stable deformation and high energy absorption efficiency is employed as the absorption components. This protection structure will have lots of advantages, e.g., stable failure pattern, high energy-dissipated capacity and clear functions for each components. For the proposed protection structure, the following important works will be carefully conducted in this project: (1) study the performance and reasonable configuration of the proposed steel-UHPC fender mainly using finite element method; (2) carry out the impact tests of the steel-UHPC fender with the influence of vessel bows by the drop hammer test system, and validate its performance and clarify its energy dissipation mechanics and modes; (3) develop the capacity design methodology for the steel-UHPC fender. The research findings will benefit the development and improvement of the analytical method and theory of the protection structure, and also provide a key foundation in designing and implementing this protection structure in practical bridge engineering.

防撞装置常用来减小或规避桥梁船撞恶性事故发生的风险，因此它的性能及稳定性至关重要。然而，传统防撞装置（尤其是在我国广泛运用的钢套箱）存在较多的不足，如耗能效率低、不稳定等。此外，目前设计防撞结构时，尚没有规范可依，且开展的试验较为有限（尤其是考虑船首影响的试验）。为此，本项目提出一种波纹钢管-超高性能混凝土（UHPC）组合的防撞结构，即将有优异抗冲击性能的UHPC面板与耗能稳定的波纹管相结合，使其具有变形模式稳定、耗能效率高、各构件功能明确等优点。针对提出的防撞结构，本项目拟开展以下工作：（1）以数值手段为主研究新型防撞结构的性能及其合理构型；（2）基于落锤试验机开展考虑船首影响的防撞结构冲击试验，验证防撞结构的性能，探明其耗能机理及模式；（3）基于能力保护理念建立防撞结构设计方法。研究成果将有助于发展和完善防撞结构的分析方法与理论，也为今后在实际桥梁工程中设置防撞结构提供重要的基础。

发展建立行之有效的桥梁防撞结构是当前船撞研究中重要而关键的问题之一，使其既能够有效地减小桥梁及船舶的动力响应，也能够有较好的长期性能。本项目以构建钢与超高性能混凝土（UHPC）组合防撞结构为总目标，提出了典型的钢-UHPC组合防撞结构构型，阐明了新型防撞结构的耗能性能，建立了新型防撞结构的分析方法。本项目开展的主要工作和成果有：（1）针对超高性能混凝土的基本性能及抗冲击性能，开展了深入动力本构理论研究，发展了能够较好地模拟UHPC抗冲击性能的动力本构，为模拟UHPC冲击动力行为提供了重要基础；（2）采用接触-碰撞有限元分析技术，较为深入系统地研究了现有钢质防撞装置的抗撞性能，指出了现有钢质防撞装置因面板过薄而存在的显著不足，以及采用UHPC面板的重要性；（3）结合波折板、波折管等耗能型构件的特点，提出了典型的钢-UHPFRC组合的防撞装置构型，并采用接触-碰撞有限元分析技术较为广泛地验证了钢-UHPFRC组合防撞装置的有效性和合理性，为该类新型防撞装置运用于实际工程中奠定了重要的基础；(4) 结合湖南大学高性能落锤试验机系统，开展了多组钢-UHPFRC组合防撞装置抗冲击性能试验，指出了UHPFRC面板相比普通混凝土面板的优越性，阐明了影响钢-UHPFRC组合防撞装置性能的主要因素，建立了精细的数值模拟方法，为实际工程中运用该类新型装置提供了分析方法及理论基础。在该项目资助下，项目团队已《Composite structures》等SCI期刊发表论文5篇，EI论文1篇，会议论文2篇，获批国家发明专利1项，实用新型专利3项，提出的防撞结构已作为多座在建桥梁的设计方案之一，有望为我国桥梁船撞防护提供新思路。