基于行波效应的钢管混凝土拱桥地震反应分析
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摘要
基于多点激励的运动方程,在考虑行波效应的前提下,应用有限元软件ABAQUS,对某下承式钢管混凝土拱桥(倾斜拱肋、倾斜吊杆)建立全桥模型,进行自振特性及地震反应分析。由2~4阶振型表明,桥面梁系刚度大于拱肋刚度;由6阶以后振型表明,桥面外刚度大于面内刚度,在低频区主要是面内振动为主。由地震反应分析结果表明:行波效应使钢管混凝土拱桥结构内力有不同程度的增大,拱脚轴力比弯矩增幅更大,增幅与加速度峰值无正比关系,当超过临界波速后拱脚弯矩增幅开始反弹。临界波速与结构动力特性、地震波频谱特征等因素有关。另外,行波效应对拱桥控制截面位移影响比较复杂。
On the basis of the motion equations of multi-support excitation and under the prerequisite that the traveling wave effect is taken into account,the finite element software ABAQUS is used to establish the model of the whole bridge of a concrete-filled steel tube(CFST) through arch bridge with inclined arch ribs and inclined hangers and the relevant natural vibration characteristics and seismic response are analyzed.The 2nd to the 4th modes show that the rigidity of the bridge deck is greater than that of the arch ribs.The modes after the 6th mode show that the out-of-plane rigidity of the deck is greater than the in-plane rigidity and in the low-frequency area,the in-plane vibration is dominant.The analysis of the seismic response demonstrates that it is the traveling effect that causes the increase of the structural internal force of the CFST bridge in different degrees,the increasing amplitude of axial force of the arch spring is even greater than that of the bending moment,the amplitude has no direct proportion relation with the peak acceleration.When exceeding the critical wave speed,the amplitude of the arch spring starts to rebound.The critical wave speed is related to the factors of the structural dynamic behavior and seismic wave frequency spectrum and moreover the influences of the traveling wave effect on the displacement of the controlled sections of the arch bridge are complicated.
On the basis of the motion equations of multi-support excitation and under the prerequisite that the traveling wave effect is taken into account,the finite element software ABAQUS is used to establish the model of the whole bridge of a concrete-filled steel tube(CFST) through arch bridge with inclined arch ribs and inclined hangers and the relevant natural vibration characteristics and seismic response are analyzed.The 2nd to the 4th modes show that the rigidity of the bridge deck is greater than that of the arch ribs.The modes after the 6th mode show that the out-of-plane rigidity of the deck is greater than the in-plane rigidity and in the low-frequency area,the in-plane vibration is dominant.The analysis of the seismic response demonstrates that it is the traveling effect that causes the increase of the structural internal force of the CFST bridge in different degrees,the increasing amplitude of axial force of the arch spring is even greater than that of the bending moment,the amplitude has no direct proportion relation with the peak acceleration.When exceeding the critical wave speed,the amplitude of the arch spring starts to rebound.The critical wave speed is related to the factors of the structural dynamic behavior and seismic wave frequency spectrum and moreover the influences of the traveling wave effect on the displacement of the controlled sections of the arch bridge are complicated.
引文
[1]苏亮,董石麟.多点输入下结构地震反应的研究现状与对空间结构的见解[J].空间结构,2006,12(1):6-11.(SU Liang,DONG Shi-lin.State of Structural SeismicResponse under Multi-Support Excitations and Sugges-tions on Spatial Structures[J].Spatial Structures,2006,12(1):6-11.in Chinese)
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[3]庄茁.ABAQUS有限元软件6.4版入门指南[M].北京:清华大学出版社,2004.
[4]郑史雄,周述华,丁桂保.大跨度钢管混凝土拱桥的地震反应性能[J].西南交通大学学报,1999,34(3):320-324.(ZHENG Shi-xiong,ZHOU Shu-hua,DING Gui-bao.The Seismic Response Behavior of Long Span CFSTArch Bridge[J].Journal of Southwest Jiaotong Uni-versity.1999,34(3):320-324.in Chinese)
[2]李忠献,史志利.行波激励下大跨度连续刚构桥的地震反应分析[J].地震工程与工程振动,2003,23(2):68-76.(LI Zhong-xian,SHI Zhi-li.Seismic Response Analysisfor Long-Span Continuous Rigid-Framed Bridges underExcitation of Traveling Waves[J].Earth Quake Engi-neering and Engineering Vibration.2003,23(2):68-76.in Chinese)
[3]庄茁.ABAQUS有限元软件6.4版入门指南[M].北京:清华大学出版社,2004.
[4]郑史雄,周述华,丁桂保.大跨度钢管混凝土拱桥的地震反应性能[J].西南交通大学学报,1999,34(3):320-324.(ZHENG Shi-xiong,ZHOU Shu-hua,DING Gui-bao.The Seismic Response Behavior of Long Span CFSTArch Bridge[J].Journal of Southwest Jiaotong Uni-versity.1999,34(3):320-324.in Chinese)
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