本文選題：高周低頻 + AASHTO規(guī)范　； 參考：《重慶交通大學(xué)》2015年碩士論文

【摘要】：近年來,隨著我國經(jīng)濟(jì)的發(fā)展,城市交通量的增加,許多建國初期建設(shè)的鋼橋在現(xiàn)有交通條件下每天都在承受著高周低頻的荷載作用,本文運(yùn)用疲勞壽命評估方法,對我國目前鋼橋疲勞進(jìn)行研究,并以重慶嘉陵江牛角沱大橋(鋼桁架)為工程實例進(jìn)行具體研究,研究的工作及結(jié)論如下:(1)在公路鋼橋抗疲勞設(shè)計理論中指出了無限壽命設(shè)計要求將構(gòu)件中的使用應(yīng)力控制在很低的水平,材料的特性并不能完全的體現(xiàn),無限壽命不經(jīng)濟(jì);安全壽命設(shè)計采用S-N曲線下降段,基于Miner累積損傷理論而來,目前被廣泛使用;損傷容限設(shè)計承認(rèn)結(jié)構(gòu)存在原始缺陷,比較貼近真實情況。(2)對公路鋼橋疲勞性能的研究,并結(jié)合國外的規(guī)范(AASHTO、Eurocode),通過對比分析,得出我國公路鋼橋規(guī)范的優(yōu)缺點。Eurocode分級比較均勻,而AASHTO分級比較細(xì),從AASHTO之中可以看到A級細(xì)節(jié)與E'級細(xì)節(jié)容許應(yīng)力幅值相差147.1MPa,各級疲勞細(xì)節(jié)區(qū)分明顯,便于計算疲勞壽命,這一點給了我們在制定疲勞規(guī)范時很好的借鑒。(3)利用有限元建立重慶嘉陵江牛角沱大橋的三維模型,通過受拉構(gòu)件的最大應(yīng)力幅值確定大橋的易損部位。(4)采用有限元,對重慶嘉陵江牛角沱大橋易損部位進(jìn)行局部模擬,得到大橋在靜力荷載作用下抗疲勞性能良好。(5)調(diào)查實橋交通荷載,運(yùn)用Monte—Carlo法模擬實際車流,采用影響線加載,運(yùn)用雨流計數(shù)法進(jìn)行計數(shù)統(tǒng)計,獲取構(gòu)件的模擬應(yīng)力譜,然后采用傳統(tǒng)疲勞壽命評估方法計算重慶嘉陵江牛角沱大橋易損構(gòu)件的剩余疲勞壽命。
[Abstract]:In recent years, with the development of our economy and the increase of urban traffic volume, many steel bridges built in the early days of the founding of the people's Republic of China are subjected to high cycle and low frequency loads every day under the existing traffic conditions. In this paper, the fatigue life assessment method is used. This paper studies the fatigue of steel bridges in China, and takes Niujiaotuo Bridge (steel truss) in Chongqing Jialing River as an engineering example. The research works and conclusions are as follows: (1) in the theory of anti-fatigue design of highway steel bridges, it is pointed out that the infinite life design requires that the use stress in the components should be controlled at a very low level, the characteristics of the material can not be fully reflected, and the infinite life is not economical; The safety life design is based on Miner cumulative damage theory and S-N curve descending section. The damage tolerance design admits that the structure has original defects, which is close to the real situation. (2) the fatigue performance of highway steel bridges is studied. By comparing and analyzing the AASHTO Eurocode, it is concluded that the advantages and disadvantages of our country's highway steel bridge code are uniform, while the AASHTO classification is fine. It can be seen from the AASHTO that the difference between the allowable stress amplitude of A level and E 'level detail is 147.1 MPa. The fatigue details of each level are distinguished obviously, and it is convenient to calculate fatigue life. This gives us a good reference in the formulation of fatigue code. (3) using finite element method to establish the three-dimensional model of Niujiaotuo Bridge in Jialing River, Chongqing, and determine the vulnerable position of the bridge through the maximum stress amplitude of the tensile member. (4) finite element method is used. The local simulation of the vulnerable parts of Niujiaotuo Bridge in Jialing River, Chongqing, shows that the fatigue resistance of the bridge is good under static load. (5) the traffic load of the bridge is investigated, the actual traffic flow is simulated by Monte-Carlo method, and the influence line is used to load the bridge. The simulated stress spectrum is obtained by using rain flow counting method, and then the residual fatigue life of vulnerable members of Niujiaotuo Bridge in Jialing River in Chongqing is calculated by traditional fatigue life evaluation method.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441.4

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