【作者】 龚凯；

【导师】 刘沐宇；

【作者基本信息】 武汉理工大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 单肋斜撑钢管混凝土拱桥是近年来出现的一种新型桥梁,它桥型美观大方、结构新颖、施工简单快捷,在桥梁建设领域具有较大发展空间。广梧高速双凤至平台段是交通部和广东省联合示范工程,考虑到在满足高速公路总体布设的情况下,要做到上跨桥的平、纵、横与下穿的高速公路线型协调一致,平顺流畅、美观、安全、经济,并充分注重景观设计,设计单位在K111+495跨线桥设计中采用了这一新颖桥梁结构形式。钢管混凝土拱桥由于材料强度的提高,施工及成桥后的稳定问题突出,而且由于拱跨的增大,桥梁结构及构件变得越来越轻柔,其动力特性也显得日益突出,如何在现有的经济及技术条件下,合理解决拱桥的稳定性及动力特性问题,成为制约该桥型进一步发展的关键因素。本文在系统介绍拱桥稳定性计算理论和动力有限元理论基础上,运用有限元软件ANSYS,以广梧高速双凤至平台段K111+495跨线桥作为工程实例,对其稳定性及动力特性进行了分析,主要进行了以下几个方面的工作:(1)考虑几何、材料双重非线性影响,采用钢管混凝土统一理论本构关系,对其施工阶段稳定性进行了分析,结果表明:考虑几何非线性,各工况稳定安全系数较线弹性稳定安全系数降低10%左右,考虑几何、材料双重非线性,各工况稳定安全系数较线弹性稳定安全系数降低60%左右。(2)考虑钢管混凝土拱桥成桥运营阶段可能的不利工况,采用线弹性屈曲方法,对其成桥状态稳定性进行分析,结果表明:该桥在成桥状态下各工况前十阶失稳模态基本相同,结构第一阶失稳特征为拱肋面外对称屈曲,桥面系扭转,说明结构的横向刚度弱于纵向刚度,容易发生面外失稳。(3)采用空间迭代法分析计算该桥前十阶自振频率、振型,结果表明:该桥拱肋的面外刚度相对较小,在桥梁振动中首先出现拱肋的面外振动,桥梁前10阶振型中有4阶为拱肋的面外振动,拱肋面外自振基频明显小于全桥竖向自振基频,表明桥梁面内外刚度相差较大,桥梁的整体竖向刚度比拱肋的横向刚度大。(4)探讨了横撑布置、传力构件、拱肋刚度、矢跨比、宽跨比对该桥动力特性的影响,结果表明:横撑对提高该桥的横向整体刚度有一定的贡献,同时也能够防止过早出现拱肋的局部横向失稳的情况;改变该桥拱肋抗压刚度对于各阶振型频率计算的影响极小,而改变抗弯刚度则对各阶振型频率的计算有一定的影响;矢跨比对钢管混凝土拱桥的自振特性影响十分显著;宽跨比仅对桥面系的面外刚度有较大影响,桥面系的面外刚度随着宽跨比的增大而降低。更多还原

【Abstract】 The single rib braces CFST arch bridge is a new type of bridge in recent years, it is elegant appearance, novel structure, the construction is simple and rapid, on the bridge construction field have great development space. The Guangwu highway Shuangfeng to Pingtai is demonstration project of ministry of communications and Guangdong province, considering meet the highway general layout, the overpass plane、vertical、cross section uniform highway alignment, design unit adopt the new type on the k111+495 overpass.Thanks to the material strength improve, the CFST arch bridge stability is outstanding on the construction and complement state, and thanks to the enlarging span, the bridge dynamic characteristics increasingly outstanding, how to solve this problem using in being economy and technical condition became restriction this type development key factor.This article systematic introduce the arch stability and dynamic theory, use finite element software, take for Guangwu highway Shuangfeng to Pingtai k111+495 overpass example, analyze the bridge’s stability and dynamic, this dissertation has dealt with the following respects:(1)On the basis of consideration of geometric nonlinearity and material nonlinearity, adopt steel tube concrete unified theory, analyze the construction state stability, the results show that the first-order coefficients of stability of the completed bridge cases decline 10% when consider geometric nonlinearity, when consider double nonlinearity, the statues of the completed bridge first-order coefficients of stability is decline 60%.(2)Adopt line elastic buckling method, analyze the complement state stability, the results show that, the first steps of instability character almost same, the first-order of structure instability character is arch rib out-surface symmetric buckling, bridge deck torsion, so can explain the bridge transverse stiffness weaker to vertical stiffness, easily occurred out-surface instability.(3)Adopt spatial iterative method, analysis and calculation the bridge first-ten order natural frequency, the results show that, the bridge out-surface stiffness is small, the out-surface vibration of the arch rib appears first in bridge vibration and there are 4 steps of out-surface vibration in first 10 step; its vertical stiffness is more greater than its out-surface stiffness.(4) Discuss the brace arrangement、connecting component、arch rib stiffness、rise-span ratio、width span ratio influence the bridge dynamic, the results show that, the brace can improve the bridge transverse stiffness and can prevent early appearance arch rib local instability situation; the change of compressive stiffness for concrete-filled steel tube have little influence to each vibration frequency, and the change of bending stiffness for concrete-filled steel tube have certain influence to each vibration frequency; rise-span ratio has great effect to the bridge dynamic, width span ratio has great influence only to bridge deck out-of plane stiffness.更多还原