整体式斜交桥梁的抗震性能与设计方法研究

In recent years, skewed bridges could constitute as high as 50% of all highway bridges in our country. A large number of earthquake damage investigations have revealed that skewed bridges turned out to have more severe earthquake damages than orthogonal bridges. Integral abutments could be introduced into skewed bridges to form skewed integral abutment bridges, which is expected to significantly improve the seismic performance of skewed bridges, reduce the seismic response and damage to the abutments, girders, and pier columns. In addition, they would also have great advantages regarding the life-cycle construction and maintenance. The coupling of bridge displacements in space, as well as the complex soil-structure interaction need to be considered for skewed integral abutment bridges, and research on the seismic performance of this type of bridge system is very limited, lagging far behind the engineering practice. In this project, a systematic study on the seismic performance and design methodology of skewed integral abutment bridges will be conducted through a combination of theoretical analysis, numerical simulation and experimental research, in order to gain a deep insight into the mechanical characteristics, anti-seismic mechanism, transfer and distribution of seismic effects, failure modes and the interaction between the bridge super-structure, sub-structure and soil, etc. Based on the research results, pile type and corresponding abutment-pile connections suitable for this type of bridge system will be identified, and reasonable seismic design method will then be developed to promote engineering application. The research results are expected to lay the foundation for broadcasting and further application of this type of bridge system, as well as compiling of relevant design specifications, so as to promote the technological innovation and development of bridge systems.

近年来我国高等级公路上斜交桥占比可达50%，而大量震害调查表明地震作用下斜交桥相比正交桥更易发生严重破坏。在斜交桥中引入整体式桥台形成整体式斜交桥，有望显著提高斜交桥的抗震性能，降低地震响应，减少桥台、主梁和墩柱等的破坏，同时具有全寿命周期建造维护方面的巨大优势。整体式斜交桥需同时考虑桥梁变形的空间耦联性与复杂的结构-土相互作用，关于其抗震性能的研究非常有限，大大滞后于工程应用。本项目拟采用理论、数值分析和试验研究相结合的方法，对整体式斜交桥的抗震性能和设计方法进行系统的研究，深入了解其受力特性、抗震机制、地震作用传递、分配机制和破坏模式，以及桥梁上部结构-下部结构-土体间的相互作用关系等。在此基础上确定适用于该种桥梁体系的桩型及相应桥台-桩连接形式，并进一步提出合理的抗震设计方法，推进工程应用。研究成果可望为此类桥梁结构的推广应用及其规程编制奠定基础，推动桥梁结构体系的技术创新和进步。

近年来我国高等级公路上斜交桥占比可达50%，而大量震害调查表明地震作用下斜交桥相比正交桥更易发生严重破坏。除震害外，外部环境对桥面伸缩缝的侵蚀等也不容忽视。在斜交桥中引入整体式桥台形成整体式斜交桥，可显著提高斜交桥的抗震性能，同时降低其全寿命周期建造维护成本。本项目结合我国工程实际，通过结构试验、理论、数值分析相结合的方法，围绕整体式斜交桥的构件及体系进行研究。首先，对整体式桥台-桩节点体系的抗震性能进行分析，研究指出采用桩头包裹橡胶板的柔性节点形式可显著增强构件的延性，减轻桩头应力。其次，对正交/斜交桥台-H形钢桩-土体系进行了拟静力试验，建立了精细有限元模型并进行非线性数值分析，指出桥台-桩-土体系的耗能能力良好，桥台斜交角度对于台后土压力以及桩身的响应均有较大影响。最后，对单跨以及多跨整体式斜交桥的抗震性能进行分析，论证了整体式斜交桥具有良好的抗震能力，也为整体式斜交桥抗震设计的关键参数给出初步建议。本项目对整体式斜交桥梁在我国的推广与应用，斜交桥抗震安全性的提高与维护成本的降低，及我国整体式桥梁抗震设计规范的进一步完善有着一定的理论和工程意义。