【作者】 张波；

【导师】 李术才；

【作者基本信息】 山东大学 ， 工程力学， 2009， 博士

【摘要】 大跨度钢管混凝土拱桥由于具有设计施工方便、经济美观等优点,应用越来越多。对于大跨度钢管混凝土拱桥地震响应的研究,目前大多数都是采用基底固结的假定,未考虑地基—结构相互作用对桥梁地震响应的影响;少数文章考虑了地基—结构相互作用,但对边界条件的处理都取得非常简化;《公路工程抗震设计规范》对于地基—结构相互作用的规定,也仅限于考虑地基变形对桥梁结构周期的影响。为了研究考虑地基—结构相互作用的大跨度钢管混凝土拱桥地震响应,本文研究了线性及非线性粘弹性人工边界,并对线性与非线性情况下粘弹性人工边界地震波动输入方法进行了研究;本文以粘弹性人工边界模拟远场地基的辐射阻尼与恢复性能,截取有效的地基计算域,以支井河特大桥——跨径为430m的上承式钢管混凝土拱桥为工程背景,建立了包括上部桥梁与下部地基的整体分析模型,在考虑地基—结构相互作用影响下对上承式大跨度钢管混凝土拱桥进行了线性与非线性地震响应研究。本文所作的主要工作如下:1、三维非线性粘弹性人工边界研究目前的粘弹性人工边界研究集中于远场介质为完全线弹性波动的情况,为了得到适于非线性分析的粘弹性人工边界,本文将远场介质假设为粘弹性材料,基于弹性波理论与粘弹性理论构造了用于模拟远场地基非线性效应的三维粘弹性人工边界。数值计算结果表明,若将半无限连续介质截断,在截断处法向及切向人工边界上施加本文得到的非线性粘弹性人工边界,可使人工边界上力和位移的条件与原波场相同,能够模拟波动自计算域向远场粘弹性介质的传播。2、三维线性及非线性粘弹性人工边界地震波动输入研究正确的地震波动输入是分析地基—结构动力相互作用的前提,本文对三维线性及非线性粘弹性人工边界地震波动输入方法进行了研究,得到了为实现地震波动输入施加在粘弹性人工边界上等效荷载F_B(t)的表达式,使等效荷载F_B(t)可以用输入地震波的位移(u)及速度((?))来完全表达,易于实现地震波动的输入。3、钢管混凝土构件受力性能数值研究分别根据三维实体有限元法和纤维单元法的钢管混凝土材料应力—应变关系得到了适于圆截面梁单元的材料应力—应变关系,数值算例证明采用由纤维单元法得到的钢管混凝土应力—应变关系应用于梁单元能取得理想的数值计算结果,并用梁单元法对钢管混凝土构件的荷载—位移滞回曲线进行了计算,取得了理想的结果。4、考虑地基—结构相互作用影响的上承式大跨度钢管混凝土拱桥地震响应研究以支井河特大桥为工程背景,分别以线性和非线性粘弹性人工边界模拟远场地基的辐射阻尼及弹性恢复性能,在考虑地基—结构相互作用的情况下对上承式大跨度钢管混凝土拱桥进行了线性、非线性地震响应分析。分析结果表明,在强度满足条件下桥基混凝土的标号没必要取太高,桥基混凝土弹模过大对上部桥梁结构地震响应有不利影响;当桥基建在坚硬的基岩上时,考虑地基—结构相互作用后桥梁地震反应内力与桥基固结时的结果相比降低,这种情况下基底固结计算结果偏安全;当桥基建在较软的基岩上时,考虑地基—结构相互作用后桥梁关键截面的内力大于桥基固结时的地震响应结果,证明基岩较软时,地基—结构相互作用对上部桥梁地震响应有可能产生不利影响,对于大跨度钢管混凝土拱桥在复杂地基条件下的抗震分析应视特殊情况作具体分析;地基—结构相互作用对上部桥梁地震响应的影响随着基岩弹模的降低而增大;横桥向的地震动输入时地基—结构相互作用对桥梁地震响应的影响大于纵向、竖向地震动输入时。本文还在考虑地基—结构相互作用条件下研究了行波效应对大跨度钢管混凝土拱桥地震响应的影响,也得出了一些有益于工程的结论,对加深大跨度钢管混凝土拱桥抗震性能的认识将提供帮助。更多还原

【Abstract】 The long-span concrete filled steel tube(CFST) arch bridge has been widely used as its advantages such as convenient construction,low cost and beautiful appearance.Now the seismic response studies of long-span CFST arch bridge mostly are based on the assumption that the arch foot is fixed without considering the foundation-structure interaction.There are a few papers on long-span CFST arch bridge seismic response considering the foundation-structure interaction,but the boundaries in these papers are very simple.The regulations on the foundation-structure interaction in the Code for Seismic Design of Highway Engineering are just about the influences of foundation deformation on the bridge period.In this paper the linear and nonlinear three dimensional viscoelastic artificial boundary and the seismic wave input methods with three dimensional viscoelastic artificial boundary were studied.The viscoelastic artificial boundary was constructed to simulate radiation damping and the elasticity recovery capacity of the medium at the far field.The full model including the bridge and foundation was made to study the seismic response of long-span CFST arch bridge with considering the foundation-structure interaction.The project background is the Zhijing River extra large bridge—deck arch bridge with 430m span.The works done in this paper are as follows:1.The research on three dimensional nonlinear viscoelastic artificial boundaryNow the viscoelastic artificial boundary is mostly studied on linear and elastic far field media.In this paper with taking the assumption that the far field medium is viscoelastic material,the three dimensional nonlinear viscoelastic artificial boundary was deduced through the elastic wave theory and viscoelastic theory.The numerical calculation results show that the conditions of force and displacement at artificial boundary are the same with those of original viscoelastic medium when the original viscoelastic medium at far field was cut and replaced with nonlinear viscoelastic artificial boundary deduced from this paper.The three dimensional nonlinear viscoelastic artificial boundary deduced from this paper can simulate the wave propagation from the computing field to the far field viscoelastic medium.2.The research on seismic wave input methods with three dimensional linear and nonlinear viscoelastic artificial boundaryThe precise seismic wave input is the premise to solve foundation-structure interaction problems.In this paper the seismic wave input methods with three dimensional linear and nonlinear viscoelastic artificial boundary were studied.The force F_B(t) applied on the viscoelastic artificial boundary to implement the seismic wave input can be expressed with the displacement(u) and velocity((?)) of input seismic wave which makes the seismic wave easy to input.3.The numerical study on CFST components mechanical behaviorThe CFST stress-strain relation suitable for beam element was deduced from three dimensional finite element method and fiber element method respectively.The numerical calculation results show that precise results can be gotten when the CFST stress-strain relation from fiber element method was used in bean element.The load-displacement hysteretic curve of CFST component was calculated with beam element.4.The research on seismic response of long-span CFST deck arch bridge with considering the foundation-structure interactionTaking the Zhijing River extra large bridge as project background,simulating radiation damping and the elasticity recovery capacity of the media at the far field with three dimensional linear and nonlinear viscoelastic artificial boundary,the linear and nonlinear seismic responses of long-span CFST deck arch bridge were studied with considering the foundation-structure interaction.The studied results show that there is bad influence on bridge seismic response if the elastic modulus of bridge foundation concrete is too large.When the bedrock is hard,the seismic response internal forces at bridge arch rib when considering the foundation-structure interaction are less than those of fixed arch foot,which shows that fixed arch foot assumption is safe in this case.When the bedrock is soft,the seismic response internal forces at bridge arch rib when considering the foundation-structure interaction are greater than those of fixed arch foot,which shows that foundation-structure interaction has bad influence on the bridge seismic response in this case.The influences of foundation-structure interaction on bridge seismic response increase with the decrease of bedrock elastic modulus.The influences of foundation-structure interaction on bridge seismic response with transverse seismic wave input are greater than those with longitudinal and vertical seismic wave inputs.In this paper the influence of traveling wave effect on bridge seismic response was also studied with considering the foundation-structure interaction which will help to know the aseismic capacity of long-span CFST arch bridge.更多还原