本文選題：剪力鉸　切入點：有限元　出處：《長安大學》2015年碩士論文　論文類型：學位論文

【摘要】：預應力混凝土桁架T構橋作為一種特殊橋型,國內(nèi)始建于上世紀80年代,工程實例并不豐富。目前正在運營的此類橋梁已出現(xiàn)各種病害,其中剪力鉸頻繁損壞這一病害比較突出。但剪力鉸作為T構橋梁的附屬結構一直未受到足夠的重視。本文以洪塘大橋為依托,對其剪力鉸結構對橋梁影響及其受力特性進行研究,并對剪力鉸結構提出改進方案。為該類橋剪力鉸的日常養(yǎng)護及維修加固提供參考。主要研究內(nèi)容如下:1)本文首先利用有限元軟件midas/civil建立洪塘大橋主橋的空間桿系模型,在各種已知荷載作用下對剪力鉸所受剪力及位移情況進行了計算分析,研究剪力鉸處在橋梁整體中的受力性能。鑒于洪塘大橋雙獨立剪力鉸的特殊設置,本文計算了剪力鉸不同損壞形式下部分主橋桁架桿件的內(nèi)力及變形,并與剪力鉸未損壞情況下對應桿件的內(nèi)力和變形進行對比,確定其影響大小。2)本文利用有限元軟件ANSYS建立剪力鉸結構細部模型,對剪力鉸各部分在不同靜力荷載作用下的應力分布進行研究。確定靜力受力較薄弱位置及其對應的應力峰值,將應力峰值與其材料的屈服強度做對比,并以此排除了剪力鉸因受靜力荷載使其構件局部達到材料強度極限而破壞的可能性。3)本文在不考慮材料腐蝕的情況下,對剪力鉸各部分按照英國規(guī)范規(guī)定的標準疲勞車作用下的應力幅和對數(shù)疲勞壽命進行計算,確定了其疲勞易損傷部位。疲勞易損傷位置有兩處:一處為7號螺栓桿底部螺栓、螺桿與墊板相接觸附近,另一處為上層墊板5號孔附近,即是剪力鉸結構日常養(yǎng)護與維修重點關注位置。4)由于洪塘大橋設計汽車荷載等級為Q-20級,相對于目前運營狀態(tài)較低。本文對剪力鉸結構不同超載量情況下應力幅及疲勞壽命進行計算。螺栓應力幅值較大且當超載量增加時其增長量明顯高于墊板,當超載量在以50%下時螺栓與墊板的疲勞壽命均不低于200萬次。5)在超載30%的情況下對剪力鉸結構提出改進方案,降低了螺栓與墊板的應力幅值,延長了結構使用壽命。在不考慮材料腐蝕影響下使螺栓與墊板處于低值應力循環(huán)狀態(tài),使其以10為底對數(shù)壽命分別達到7.20與7.07。為剪力鉸維修加固提供參考。
[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.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441

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本文編號：1644161