钢-混凝土组合箱梁刚构桥弹塑性地震反应分析

Elastic-plastic Time History Reaction Analysis of Steel-concrete Composite Box Girder Rigid-frame Bridge

随着钢-混凝土组合刚构桥在震害比较严重的地区发展得到了很好应用,有必要深入研究组合刚构桥在地震下的弹塑性时程动力响应。以三跨圆端形钢管混凝土桥墩-钢混凝土组合箱梁连续刚构桥为分析对象,利用ABAQUS有限元软件建立了三维实体有限元模型,基于合理的钢材和混凝土本构关系,考虑了桥墩钢管与混凝土相互作用,以及钢梁、栓钉和混凝土板之间粘结滑移,分析了桥梁的自振特性;计算了4种不同地震工况作用下对墩顶位移、加速度和墩底剪力等地震响应的影响和各控制点应力应变变化特征;探讨了箱梁双重组合作用、地震作用方向、墩高、墩截面对刚构桥抗震耗能分配机制。结果表明:①地震烈度越大,刚构桥的地震响应越大,中跨墩顶负弯矩处和跨中位置的双重组合作用有利于结构抗震,墩高和墩截面尺寸对桥墩塑性耗能影响大;②边跨钢管表面的横向变形系数最大达到0.98,表明钢管对混凝土产生较强的套箍约束作用;③边跨和中跨的墩底、墩顶处应力较大,容易形成塑性铰,需采取有效的安全构造措施提高桥梁的抗震性能。

With the development of steel-concrete composite rigid frame bridges in areas with severe earthquake damage.It is necessary to study the elastoplastic time-history dynamic response of composite bridges under earthquake.Based on the 3 across the rounded shape steel tube concrete pier-steel concrete composite box girder of continuous rigid frame bridge as the analysis object,using the ABAQUS finite element analysis software of three-dimensional solid finite element model is established,based on rational constitutive relation of the steel and concrete,considering the interaction between steel tube and concrete piers,and steel beam,stud,and bond slip between concrete slab,the natural vibration characteristics of the bridge are analyzed.The effects of four different seismic conditions on the seismic responses of pier top displacement,ac celeration and pier bottom shear and the stress-strain variation characteristics of each control point were calculated.The distribution mechanism of seismic energy consumption of rigid frame bridge by double combination of box girder,direction of seismic action,pier height and pier section is discussed.The results show that:①The greater the seismic intensity is,the greater the seismic response of the rigid frame bridge is,and the double combination of the negative moment at the top of the midspan pier and the midspan position is conducive to the seismic resistance of the structure,the pier height and pier section size have great influence on the plastic energy dissipation of the pier.②The maximum transverse deformation coefficient of the steel pipe surface reaches 0.98,indicating that the steel pipe has a strong constraint effect on concrete by the collar;③The stress at the bottom and top of pier of side span and middle span is large,and it is easy to form plastic hinge.Therefore,effective structural safety measures should be taken to improve the seismic performance of the bridge.