超大跨钢管混凝土拱桥失稳机理及强震作用的动力稳定性研究

Large slenderness ratio, small width span ratio and small aspect ratio are salient features of super long-span concrete-filled steel tubular(CFST) arch bridge, whose structural stiffness is relatively small and stability problem in-plane and out of plane is prominent. However, research on nonlinear dynamic stability under seismic action is still scarce, it is the key problem unsolved for super long-span CFST arch bridge. Nonlinear dynamic stability of super long-span CFST arch bridge will be researched in this project, a combination method of theoretical analysis, model experiments and numerical analysis will be adopted, a stress-strain relationship model of core concrete and CFST member will be put forward, a double nonlinear finite element model of super long-span CFST arch bridge considering geometric non-linearity and material non-linearity will be established; Calculation formula for elastic integral stability coefficient and nonlinear stability bearing capacity analysis method for members and whole bridge in super large span CFST arch bridge considering structural parameters will be put forward; Law of damage evolution under earthquake action will be revealed by analyzing changes of internal force and deformation under earthquake action considering spatial effect; Judgment criterion of nonlinear dynamic instability and analysis method for stability bearing capacity will be put forward; Index system and weight system for dynamic stability based on energy changes will be established, an overall dynamic stability evaluation method for super long-span CFST arch bridge based on analytic hierarchy process will be put forward, weak parts influencing overall dynamic stability of super long-span CFST arch bridge will be obtained, which can provide basis and reference for seismic design of engineering.

超大跨钢管混凝土拱桥特点是长细比大、宽跨比和宽高比小，结构刚度相对较小，面内和面外稳定性问题比较突出，地震作用下非线性动力稳定问题研究还比较缺乏，是钢管混凝土拱桥向更大跨径发展的瓶颈。本项目围绕超大跨钢管混凝土拱桥非线性动力稳定性问题，采用理论分析、模型试验和数值分析相结合，提出核心混凝土和钢管混凝土构件的应力应变关系模型，建立超大跨钢管混凝土拱桥的双重非线性有限元模型；提出考虑结构参数超大跨钢管混凝土拱桥各部分构件及整桥的弹性整体稳定系数计算公式和非线性稳定承载力分析方法；通过空间作用效应地震作用下的内力与变形变化，揭示超大跨钢管混凝土拱桥在强震作用下的损伤演变规律；提出非线性动力失稳判别准则和稳定承载力分析方法；建立基于能量变化的动力稳定度指标体系及其权重体系，提出基于层次分析法的超大跨钢管混凝土拱桥整体动力稳定度评估方法，得到影响整体动力稳定度的薄弱部位，为工程抗震设计提供依据。

超大跨钢管混凝土拱桥特点是长细比大、宽跨比和宽高比小，结构刚度相对较小，面内和面外稳定性问题比较突出，地震作用下非线性动力稳定问题研究还比较缺乏，是钢管混凝土拱桥向更大跨径发展的瓶颈。本项目围绕超大跨钢管混凝土拱桥非线性动力稳定性问题，采用理论分析、模型试验和数值分析相结合，提出核心混凝土和钢管混凝土构件的应力应变关系模型，建立超大跨钢管混凝土拱桥的双重非线性有限元模型；提出考虑结构参数超大跨钢管混凝土拱桥各部分构件及整桥的弹性整体稳定系数计算公式和非线性稳定承载力分析方法；通过空间作用效应地震作用下的内力与变形变化，揭示超大跨钢管混凝土拱桥在强震作用下的损伤演变规律；提出屈服临界曲率差、峰值临界曲率差和极限临界曲率差的计算公式；建立基于能量变化的动力稳定度指标体系及其权重体系，提出非线性动力失稳判别准则和稳定承载力分析方法，可以判别结构钢管屈服、混凝土达到峰值应变时对应的临界状态，提高工程实用性，为工程抗震设计提供依据。