【作者】 叶毅；

【导师】 张哲；

【作者基本信息】 大连理工大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 自锚式斜拉—悬索协作体系桥是一种崭新的桥型,该桥型具有受力合理,抗风性能好,施工安全、工程造价低及对不良地质条件适应性好等优点。目前国内外关于自锚式斜拉—悬索协作体系桥的相关研究较少,而该桥型在特定条件下有其独特的优势,因此有必要对该桥型展开系统的研究。本文结合交通部西部交通建设科技项目“斜拉—悬索协作体系桥梁的研究”课题,以拟建的大连跨海大桥为工程背景,对自锚式斜拉—悬索协作体系桥的简化近似计算方法、结构参数的敏感性,端吊杆破断对结构受力性能的影响及斜拉—悬索协作体系桥在现有悬索桥加固中的应用等问题进行了深入的研究,主要研究内容如下：1.基于能量原理,结合该桥型的结构特点,提出了对自锚式斜拉—悬索协作体系桥内力和变形进行简化分析的分离近似法。该方法将自锚式斜拉—悬索协作体系桥的主缆、拉索和吊杆截开,用未知力来代替,分别取连续加劲梁和缆索系统为分离体进行分析,导出了求解加劲梁内力、挠度和缆索系统内力的基本公式。最后以已建成的庄河建设大桥为例,对分离近似法所得结果与有限元方法结果进行了比较,二者吻合较好。2.以金州海湾大桥设计方案为背景,以分离近似法为基础,对混合梁自锚式斜拉—悬索协作体系桥结构参数变化对其静力性能的影响进行了研究。结果表明：吊跨比对结构影响较大,随着吊跨比的增大,结构整体刚度减小,主梁跨中最大挠度及最大弯矩均有较大幅度的增加；增大悬吊部分主缆矢跨比可以提高结构刚度,但是其已经退化为一个局部参数；增大加劲梁抗弯刚度虽然能减小加劲梁主跨挠度,但是其弯矩也会增加；增加主缆抗拉刚度可较大程度的提高结构的整体刚度,使得主梁跨中最大挠度及弯矩大幅减小,而主缆最大拉力则相应增加。3.考虑结构构件的材料、几何尺寸等各项参数的不确定性,应用响应面法对自锚式斜拉—悬索协作体系桥的动力特性以及静风失稳临界风速进行了随机分析。采用了非线性有限元计算模型,研究了各随机变量的变异对自锚式斜拉—悬索协作体系桥的动力特性以及静风失稳临界风速的影响规律,并对所拟合的响应面的精度进行了验证。结果表明：对于自锚式斜拉—悬索协作体系桥,主梁质量密度的变异对其低阶振动频率的影响最为敏感：而对静风失稳临界风速影响较为显著的为主梁的质量密度和截面面积的变异。通过这一研究结果可以清楚地了解各随机因素对自锚式斜拉—悬索协作体系桥结构响应的影响程度,为合理设计提供理论依据。4.斜拉—悬索协作体系桥的主要问题之一是端吊杆应力拉压反复,易产生疲劳。针对这一问题,在吊杆损伤、破断相关理论基础之上分析了自锚式斜拉—悬索协作体系桥端吊杆破断对结构受力性能的影响规律。首先对端吊杆不同破断工况下的自锚式斜拉—悬索协作体系桥进行了静力分析；其后,考虑吊杆破断时间的影响,对端吊杆破断后的结构进行了时程分析,并对结构的静态效应及动态效应进行了对比。研究结果表明：在自锚式斜拉—悬索协作体系桥端吊杆破断后,与之相邻的吊杆内力重分布现象较为明显,而主梁位移、弯矩及主缆拉力则变化不大；对自锚式斜拉—悬索协作体系桥与端吊杆、次端吊杆相邻的吊杆适当提高安全系数,当端吊杆或次端吊杆发生破断后则不会引起结构的渐次破坏。5.以大连小平岛圣岛大桥加固改造工程为例,提出了一种利用斜拉—悬索协作体系加固改造现有悬索桥的方法。对加固改造工程的方案比选、加固改造前后结构体系的变化及相应力学特性进行了探讨；就加固改造后所形成的斜拉—悬索协作体系在力学性能及经济性方面进行了优化。结果表明：利用斜拉—悬索协作体系对现有悬索桥进行加固改造、大幅度提高原桥承载力是切实可行的。该方法不仅显著地改善了原桥的受力性能,有效地提高了桥梁的承载能力和通行能力,同时还最大程度的利用了原桥的结构和材料,在经济性上具有优势。原悬索桥在加固改造后所形成的斜拉—悬索协作体系与传统的斜拉—悬索协作体系相比,其在体系形成顺序及受力特性上等有所不同；所包含的悬索体系和斜拉体系各自承担自身的恒载,同时协同作用,共同承担等级提高后的活载。更多还原

【Abstract】 Self-anchored cable-stayed suspension bridge is a new type of bridge. It will become a competitive bridge type in the long-span bridge system because of strength rationality, construction safety, good adaptability to poor geological conditions and economy. At present, there are few relevant papers on self-anchored cable-stayed suspension bridge. But this bridge type has a particular advantage under specifically condition. It is necessary to carry out systematic study on this new bridge type. Combined western traffic construction scientific and technological project of Ministry of Communications and under the background of Dalian Gulf Bridge, this paper studies the simplified calculation method, sensitiveness of structure parameter, the influence of fracture of end hanger to the performance of self-anchored cable-stayed suspension bridge and strengthening the existing suspension bridges by changing suspension system into cable stayed suspension system. The main research work covers the following aspects:1. Based on energy principle, a named isolated body approximate method is proposed to calculate the behavior of self-anchored cable-stayed suspension bridge. The main cable, stayed cables and hangers of self-anchored cable-stayed suspension bridge are truncated and replaced by unknown forces in this method. The formulas for calculating the internal forces and deformation of girder and the internal forces of cable system are deduced. Take Construction bridge in Zhuanghe as an example, the calculation results of isolated body approximate method and finite element method is compared and the results of this two methods are matched well.·2. Under the background of Jinzhou Gulf Bridge, the influence of structure parameters to the behavior of self-anchored cable-stayed suspension bridge with steel-concrete mixed girder is researched. The result shows that:the influence of suspension-span ratio is significant. With suspension-span ratio increase the stiffness of structure is decreased and the max deformation and bending moment of the main span is increased greatly. The stiffness of structure can be increased by increasing rise-span ratio of suspension part, but the rise-span ratio has been degraded to be a local parameter. Though the deformation of the main span can be reduced by increasing the flexural stiffness of girder, the moment of girder will be greater. The stiffness of structure is increased greatly with the increase of tension stiffness of the main cable. The max deformation and bending moment of the main span deduce significantly while the tension force of it increase.3. Considering the uncertainties of the material and the physical dimension, the response surface approach is adopted to analyze vibration characteristics and critical wind speed of self-anchored cable-stayed suspension bridge. The nonlinear FEM model is established and the influences of random variables to vibration characteristics and critical wind speed of self-anchored cable-stayed suspension bridge is researched. The result presents that the dense of girder is most sensitive to the low-order frequencies of self-anchored cable-stayed suspension bridge while the dense and section area of girder impact the critical wind speed obviously. The conclusion mentioned above can help the designers to understand the influence extent of each random variable to the performance of self-anchored cable-stayed suspension bridge and supply theoretical foundation to design practice.4. It is one of the most important questions to cable-stayed suspension bridge that the end hanger is always under alternative stress which cause the hanger fatigue. Aiming at this fact, the research on influence law of end hanger fracture to mechanical properties of self-anchored cable-stayed suspension bridge is carried out based on damage theory of hanger. Static analysis of this type bridge under different fracture conditions is performed firstly. Then, considering time effect time-history analysis of mechanical properties under the end hanger fractured is conducted. The investigation indicates that under static effects internal force redistribution of the hangers adjacent of fractured hanger is significantly while the beam deflection, moment and tension of main cable of self-anchored cable-stayed suspension bridge are influenced little. By enhance the safety factor of end hanger and its adjacent hanger of self-anchored cable-stayed suspension bridge the structure will not fail foot by foot when end hanger is fractured.5. Based on transformation project of Shengdao bridge, a method of strengthening the existing suspension bridges by changing suspension system into cable-stayed suspension system is presented. The choice of strengthening manners, the changing of the structural system and the static behavior of the bridge before and after the strengthening is discussed. Besides that the characteristics and economic optimize of the cable-stayed suspension system is preformed also. The results indicate that it is feasible to strengthening the existing suspension bridges and greatly improve capacity of carrying load of it by this way. The mechanical behavior of original bridge is improved while the materials of the original bridge can be used to the greatest degree which makes economic advantage. Comparing the cable-stayed-suspension system by strengthening the existing suspension bridge to the traditional cable-stayed-suspension system, the two systems are formed in different order. The suspension system and stayed cable system bear their dead load independent and bear live load together.更多还原