剪力铰对预应力砼桁架T构桥影响及其受力分析

发布时间：2018-03-21 14:00

本文选题：剪力铰　切入点：有限元　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土桁架T构桥作为一种特殊桥型,国内始建于上世纪80年代,工程实例并不丰富。目前正在运营的此类桥梁已出现各种病害,其中剪力铰频繁损坏这一病害比较突出。但剪力铰作为T构桥梁的附属结构一直未受到足够的重视。本文以洪塘大桥为依托,对其剪力铰结构对桥梁影响及其受力特性进行研究,并对剪力铰结构提出改进方案。为该类桥剪力铰的日常养护及维修加固提供参考。主要研究内容如下:1)本文首先利用有限元软件midas/civil建立洪塘大桥主桥的空间杆系模型,在各种已知荷载作用下对剪力铰所受剪力及位移情况进行了计算分析,研究剪力铰处在桥梁整体中的受力性能。鉴于洪塘大桥双独立剪力铰的特殊设置,本文计算了剪力铰不同损坏形式下部分主桥桁架杆件的内力及变形,并与剪力铰未损坏情况下对应杆件的内力和变形进行对比,确定其影响大小。2)本文利用有限元软件ANSYS建立剪力铰结构细部模型,对剪力铰各部分在不同静力荷载作用下的应力分布进行研究。确定静力受力较薄弱位置及其对应的应力峰值,将应力峰值与其材料的屈服强度做对比,并以此排除了剪力铰因受静力荷载使其构件局部达到材料强度极限而破坏的可能性。3)本文在不考虑材料腐蚀的情况下,对剪力铰各部分按照英国规范规定的标准疲劳车作用下的应力幅和对数疲劳寿命进行计算,确定了其疲劳易损伤部位。疲劳易损伤位置有两处:一处为7号螺栓杆底部螺栓、螺杆与垫板相接触附近,另一处为上层垫板5号孔附近,即是剪力铰结构日常养护与维修重点关注位置。4)由于洪塘大桥设计汽车荷载等级为Q-20级,相对于目前运营状态较低。本文对剪力铰结构不同超载量情况下应力幅及疲劳寿命进行计算。螺栓应力幅值较大且当超载量增加时其增长量明显高于垫板,当超载量在以50%下时螺栓与垫板的疲劳寿命均不低于200万次。5)在超载30%的情况下对剪力铰结构提出改进方案,降低了螺栓与垫板的应力幅值,延长了结构使用寿命。在不考虑材料腐蚀影响下使螺栓与垫板处于低值应力循环状态,使其以10为底对数寿命分别达到7.20与7.07。为剪力铰维修加固提供参考。
[Abstract]:As a special bridge type, prestressed concrete truss T-bridge was built in China in -20s. The engineering examples are not abundant. The frequent damage of shear hinge is a serious disease, but the shear hinge as a subsidiary structure of T-structure bridge has not been paid enough attention to. This paper relies on Hongtang Bridge. The influence of shear hinge structure on bridge and its mechanical characteristics are studied. An improved scheme of shear hinge structure is put forward to provide reference for the daily maintenance and maintenance and reinforcement of shear-hinge of this kind of bridge. The main research contents are as follows: 1) in this paper, the spatial bar model of the main bridge of Hongtang Bridge is established by using finite element software midas/civil. Under various known loads, the shear force and displacement of shear hinge are calculated and analyzed, and the mechanical behavior of shear hinge in the whole bridge is studied. In view of the special setting of double independent shear hinge of Hongtang Bridge, In this paper, the internal forces and deformations of truss members of some main bridges under different damage forms of shear hinges are calculated, and compared with the internal forces and deformations of corresponding members under the condition that shearing hinges are not damaged. In this paper, the detail model of shear-hinge structure is established by using finite element software ANSYS. The stress distribution of different parts of shear hinge under different static loads is studied. The weak position of static force and its corresponding peak stress are determined, and the stress peak value is compared with the yield strength of the material. In this way, the possibility of failure of shear hinge due to the local strength limit of the member subjected to static load is eliminated. 3) in this paper, the corrosion of the material is not considered. According to the calculation of the stress amplitude and logarithmic fatigue life of the shearing hinge under the action of the standard fatigue vehicle specified in the British Code, the fatigue vulnerable position of the shearing hinge is determined. There are two locations of the fatigue vulnerability: one is the bolt at the bottom of the No. 7 bolt rod, The screw is in contact with the gasket, and the other is near the upper gasket hole 5, that is, the focus of attention on the daily maintenance and maintenance of the shearing hinge structure.) because of the design of the Hongtang Bridge, the vehicle load grade is Q-20. In this paper, the stress amplitude and fatigue life of shear-hinge structure under different overloads are calculated. The stress amplitude of bolt is larger and the increase amount of bolt is obviously higher than that of gasket when overload is increased. The fatigue life of bolt and plate is not less than 2 million times when the overload is 50%) the improved scheme of shear hinge structure is put forward under the condition of overload 30%, which reduces the stress amplitude of bolt and plate. The service life of the structure is prolonged. The bolt and plate are in low value stress cycle state without considering the influence of material corrosion, and the logarithmic life of 10 is 7.20 and 7.07 respectively, which provides a reference for the maintenance and reinforcement of shear-hinge.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441

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