【作者】 童建胜；

【导师】 陈世民； 周水兴；

【作者基本信息】 重庆交通大学 ， 工程力学， 2010， 硕士

【摘要】 近20年内,钢管混凝土拱桥在我国已经得到广泛应用,在目前已建和在建的大跨径钢管混凝土拱桥,其施工多采用无支架吊装法、转体施工法架设空钢管拱肋,合拢后再逐根浇筑管内混凝土,按此方法施工,钢管在与混凝土形成复合截面之前,因承受自重和湿混凝土重量,不可避免地会产生初应力。钢管初应力使钢管屈服提前,从而影响到钢管混凝土拱桥的承载力。本文开展了初应力对钢管混凝土拱桥承载力的影响计算,同时为验证计算的正确性和可靠性,针对性的设计了考虑钢管初应力对其力学性能影响的试验方案。主要研究工作如下:①基于空间梁单元非线性几何方程,运用了计入初应力和初应变的一般线弹性本构关系的显式切线刚度矩阵,为本文研究钢管初应力对钢管混凝土拱桥极限承载力的影响奠定了理论基础;②在收集和总结国内外钢管混凝土的本构关系后,合理的选取了钢管和混凝土的本构关系,采用空间梁单元来计算极限承载力;③展了单肢钢管混凝土拱桥在不同初应力系数、不同矢跨比、不同含钢率、不同跨径下的承载力及影响系数k p的计算。结果表明,对于钢管混凝土拱桥极限承载力计算,应同时考虑双重非线性影响;钢管初应力使钢管混凝土拱桥极限承载力下降,具体降低幅度与初应力系数、矢跨比、跨径、含钢率、几何非线性等因素有关;含钢率不变的情况下,随着跨径增大,初应力对承载力的影响相对减小。以承载力下降10%为界限,单肢钢管混凝土拱桥的钢管初应力系数不应超过0.2。④通过对单肢钢管混凝土拱桥考虑钢管初应力的极限承载力分析,应用最小二乘法理论,在MATLAB下实现了不同跨径、不同矢跨比的单肢钢管混凝土拱桥承载力影响系数计算公式。⑤为验证理论计算,有针对性的开展了考虑钢管初应力影响的单肢钢管混凝土模型拱设计,方案一为拱顶单点加载;方案二为四分点单点加载。⑥针对两个方案开展了不同初应力系数、不同跨径下的承载力计算,结果表明:拱顶加载模型的极限承载力和影响系数k p值要高于四分点加载模型拱。⑦设计了整个模型的试验过程,为接下来模型试验的顺利实施,提供了方法和手段。更多还原

【Abstract】 In the last 20 years, The CFST has been widely adopted in the arch bridge building. In construction of long-span arch bridge, the main methods are non-bracket construction technology or the swing technology. Under these methods, before the formation of CFST arch bridge, steel tube will withstand the weights of itself and the wet concrete; this will cause the initial stress of the steel tube inevitably. The initial stress forces the steel tube to prior reach the yield point of material, which will affect the bearing capacity of CFST arch bridge.This paper considered the initial stress in the calculation of the CFST arch bridge’s bearing capacity, at the same time in order to verify the accuracy and reliability of computing, purposeful design the model experiment which considered the initial stress on the mechanical properties. Main research works are as follows:①. Based on spatial beam element nonlinear geometry equation, explicit tangent stiffness matrix of spatial beam element contained the initial stress and the initial strain in general elastic configuration relationship has been applied. Laid the theoretical foundation in studying the initial stress on the ultimate bearing capacity of CFST arch bridge.②. Based on collecting and summarizing the constitutive relation of CFST, select the constitutive relation of the steel and concrete reasonable, the computation of ultimate bearing capacity of CFST arch bridge will be completed by spatial beam element.③. The ultimate capacity and the influence factor K p of single-tube CFST arch bridges including different initial stress factorβ, span and rise-span ratio as well as sectional steel ratioαhave been performed. The analytical results show when bearing capacity analysis of steel tube initial stress to CFST arch bridge was performed, both material nonlinear and geometry nonlinear should be simultaneously included; steel tube initial stress can reduce bearing capacity of CFST arch bridge. However, the reduced extents have connection with steel tube initial stress factorβ, rise-span ratio, sectional steel ratioαand span etc. If the reduction extent of bearing capacity does not exceed 10%, thus initial stress factor of single-tube CFST arch bridge should be limited to 0.2.④. By studying the ultimate bearing capacity of single-tube CFST arch bridge which considering the steel tube initial stress, application the theory of least square method, the formulas of bearing capacity influence factor under different span and rise-span ratio have been given for single-tube CFST arch bridge by use of MATLAB.⑤. To verify the theoretical calculation, design two models of single-tube CFST arch bridge, one is single point loading on vault; another one is single point loading on one quarter of span.⑥. For the two models, the ultimate capacity analysis of single-tube CFST arch bridges span as well as sectional steel ratioαhave been performed. The results show that the model arch bridge loading on vault compared the single point loading on one quarter of span; the ultimate capacity and the influence factor K p are larger.⑦.The whole model test process were designed, For the later model test successfully, it provide methods and means.更多还原