酸雨環(huán)境下斜拉索應(yīng)力腐蝕與腐蝕疲勞試驗研究
發(fā)布時間：2019-07-02 10:32
【摘要】：斜拉橋以優(yōu)美的結(jié)構(gòu)形式,輕盈的體態(tài)和獨特的受力特點而備受橋梁設(shè)計者們青睞,我國也成為斜拉橋建造大國,但斜拉索的應(yīng)力腐蝕與疲勞腐蝕一直是斜拉橋研究的前沿課題,本文以斜拉橋拉索系統(tǒng)在酸雨環(huán)境下的加速試驗為支撐,通過對斜拉索施加交變荷載、靜態(tài)荷載和無荷載作為對比條件,研究斜拉索的腐蝕過程及疲勞腐蝕與應(yīng)力腐蝕機理。在試驗結(jié)果的處理上,以失重法來衡量不同的荷載條件下斜拉索的腐蝕速率,同時以《中國大氣腐蝕調(diào)查報告》中的大氣腐蝕監(jiān)控點的大氣暴曬腐蝕速率為基本對比條件,得出在加速試驗中個試件的腐蝕情況與腐蝕速率,同時得出在酸雨環(huán)境下斜拉索的不同受力形式的腐蝕速率與大氣腐蝕速率的等同性;通過試驗研究得出:三種試件在5天試件內(nèi)的腐蝕速率基本一致,在15天的試驗交變荷載條件下試件的腐蝕速率明顯大于靜態(tài)荷載條件下試件的腐蝕速率與無荷載條件下試件的腐蝕速率,而靜態(tài)荷載條件下試件的腐蝕速率又大于無荷載條件下試件的腐蝕速率;通過與西南地區(qū)大氣暴曬實驗點的腐蝕數(shù)據(jù)做對比得出:交變荷載下腐蝕速率30天后的每天的腐蝕速率為實際大氣暴曬下的2年;靜態(tài)荷載下30天后的每天的腐蝕速率為實際大氣暴曬下的1.46年。同時通過掃描電子顯微鏡觀測到應(yīng)力腐蝕與疲勞腐蝕的不同及微裂紋的擴展情況,及裂紋形核的形成條件與納米級裂紋的擴展,疲勞腐蝕中主裂紋與次裂紋的擴展條件,及在應(yīng)力腐蝕中小裂紋與大裂紋的發(fā)展趨勢。對腐蝕的結(jié)果進行MATLAB中元胞自動機的編碼進行模擬在交變荷載與靜態(tài)荷載條件下試件的腐蝕腐蝕動力學(xué),從而得出均勻腐蝕與點蝕的關(guān)系;以ANSYS12.0有限元軟件為依托,對不同腐蝕情況下的斜拉索進行有限元分析,得出應(yīng)力與蝕坑深度的關(guān)系,應(yīng)力與蝕坑間距的關(guān)系。在得到以上的各個結(jié)論后,提出斜拉橋拉索壽命預(yù)測公式,通過重慶地區(qū)的斜拉橋進行預(yù)測公式的計算,在通過以上的各個結(jié)論推出拉索失效的判據(jù),同時以南太湖大橋為例進行了斜拉索壽命分析。
[Abstract]:The cable-stayed bridge has been favored by the bridge designers in the form of graceful structure, light posture and special stress. The cable-stayed bridge also becomes a large-power cable-stayed bridge, but the stress corrosion and fatigue corrosion of the stay cable have been the leading problem in the research of the cable-stayed bridge. In this paper, the accelerated test of cable-stayed cable system in acid rain environment is supported, and the corrosion process of the stay cable and the mechanism of fatigue corrosion and stress corrosion are studied by applying the alternating load, static load and no-load to the stay cable as the comparison condition. On the basis of the test results, the corrosion rate of the stay cable under different loading conditions is measured by the weight loss method, and the atmospheric corrosion rate of the atmospheric corrosion monitoring point in the Report of the Atmospheric Corrosion in China is the basic contrast condition. The corrosion rate and the corrosion rate of the test piece in the accelerated test are obtained, and the equivalent of the corrosion rate and the atmospheric corrosion rate in different stress forms of the stay cable under the acid rain environment is obtained. The test results show that the corrosion rate of the three test pieces in the 5-day test piece is basically the same, The corrosion rate of the test piece is obviously higher than the corrosion rate of the test piece under the static load condition and the corrosion rate of the test piece under the static load condition is greater than the corrosion rate of the test piece under the condition of no load; It is concluded that the rate of corrosion per day after 30 days of the corrosion rate under the alternating load is 2 years of the actual exposure to the atmosphere, and the rate of corrosion per day after 30 days of static loading is 1.46 years of the actual exposure to the atmosphere. At the same time, by scanning electron microscope, the difference of stress corrosion and fatigue corrosion and the expansion of micro-cracks, the formation condition of crack nucleation and the expansion of the nano-scale crack, the extension condition of the main crack and the secondary crack in the fatigue corrosion, And the development trend of small cracks and large cracks in stress corrosion. The corrosion and corrosion dynamics of the specimen under the condition of alternating load and static load are simulated by the coding of the cellular automaton in MATLAB, and the relationship between the uniform corrosion and the pitting corrosion is obtained. Based on the ANSYS12.0finite element software, The relationship between the stress and the depth of the pit and the relation between the stress and the pit pitch are obtained by the finite element analysis of the stay cable under different corrosion conditions. After the conclusion of the above conclusions, the formula of the cable life prediction of the cable-stayed bridge is put forward, and the calculation of the prediction formula is carried out through the cable-stayed bridge in the Chongqing area, and the criterion of the cable failure is introduced through the above conclusions, and the life analysis of the stay cable is carried out in the south of the Taihu Bridge as an example.
【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;U446
本文編號：2508863
[Abstract]:The cable-stayed bridge has been favored by the bridge designers in the form of graceful structure, light posture and special stress. The cable-stayed bridge also becomes a large-power cable-stayed bridge, but the stress corrosion and fatigue corrosion of the stay cable have been the leading problem in the research of the cable-stayed bridge. In this paper, the accelerated test of cable-stayed cable system in acid rain environment is supported, and the corrosion process of the stay cable and the mechanism of fatigue corrosion and stress corrosion are studied by applying the alternating load, static load and no-load to the stay cable as the comparison condition. On the basis of the test results, the corrosion rate of the stay cable under different loading conditions is measured by the weight loss method, and the atmospheric corrosion rate of the atmospheric corrosion monitoring point in the Report of the Atmospheric Corrosion in China is the basic contrast condition. The corrosion rate and the corrosion rate of the test piece in the accelerated test are obtained, and the equivalent of the corrosion rate and the atmospheric corrosion rate in different stress forms of the stay cable under the acid rain environment is obtained. The test results show that the corrosion rate of the three test pieces in the 5-day test piece is basically the same, The corrosion rate of the test piece is obviously higher than the corrosion rate of the test piece under the static load condition and the corrosion rate of the test piece under the static load condition is greater than the corrosion rate of the test piece under the condition of no load; It is concluded that the rate of corrosion per day after 30 days of the corrosion rate under the alternating load is 2 years of the actual exposure to the atmosphere, and the rate of corrosion per day after 30 days of static loading is 1.46 years of the actual exposure to the atmosphere. At the same time, by scanning electron microscope, the difference of stress corrosion and fatigue corrosion and the expansion of micro-cracks, the formation condition of crack nucleation and the expansion of the nano-scale crack, the extension condition of the main crack and the secondary crack in the fatigue corrosion, And the development trend of small cracks and large cracks in stress corrosion. The corrosion and corrosion dynamics of the specimen under the condition of alternating load and static load are simulated by the coding of the cellular automaton in MATLAB, and the relationship between the uniform corrosion and the pitting corrosion is obtained. Based on the ANSYS12.0finite element software, The relationship between the stress and the depth of the pit and the relation between the stress and the pit pitch are obtained by the finite element analysis of the stay cable under different corrosion conditions. After the conclusion of the above conclusions, the formula of the cable life prediction of the cable-stayed bridge is put forward, and the calculation of the prediction formula is carried out through the cable-stayed bridge in the Chongqing area, and the criterion of the cable failure is introduced through the above conclusions, and the life analysis of the stay cable is carried out in the south of the Taihu Bridge as an example.
【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;U446
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本文編號：2508863
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