混凝土橋梁耐久性評估與預(yù)測
發(fā)布時(shí)間：2018-08-22 11:25
【摘要】：混凝土橋梁是公路和城市橋梁的主導(dǎo)橋型。由于其材料自身和使用環(huán)境的因素，往往存在各種各樣的耐久性問題，必須進(jìn)行周期性的維修養(yǎng)護(hù)。由于工程實(shí)際問題的復(fù)雜性，混凝土結(jié)構(gòu)耐久性評估和壽命預(yù)測會(huì)遇到大量隨機(jī)、模糊以及不完整的信息，尚無理想的混凝土橋梁耐久性評估及壽命預(yù)測方法。在綜述國內(nèi)外相關(guān)文獻(xiàn)的基礎(chǔ)上，對混凝土橋梁耐久性相關(guān)問題開展了如下研究： 1.提出一種基于層次分析法和證據(jù)理論的混凝土橋梁耐久性狀況群體評估方法。首先，將全橋劃分為上部結(jié)構(gòu)、下部結(jié)構(gòu)和橋面系三部分，并進(jìn)一步劃分為一系列部件、構(gòu)件；其次，各個(gè)層次上指標(biāo)權(quán)重的確定和底層指標(biāo)的耐久性狀況評估均由評估專家群體分別完成，專家個(gè)體權(quán)重由專家個(gè)體評估結(jié)果與理想結(jié)果的模糊距離確定；然后，將專家的評估意見加權(quán)平均，獲得專家組的評估意見；最后，采用證據(jù)合成理論，從底層開始，逐層評估，直至得出最終評估結(jié)果。采用該方法評估廣清高速公路天坪嶺大橋和湖南常寧茭河口大橋的評估，用于驗(yàn)證該方法的可行性。 2.在對既有混凝土結(jié)構(gòu)碳化模型總結(jié)分析的基礎(chǔ)上，提出預(yù)測碳化深度的貝葉斯更新方法。首先，選擇幾個(gè)碳化模型并平均賦以權(quán)重，以其加權(quán)平均值作為先驗(yàn)?zāi)Ｐ皖A(yù)測碳化深度；然后，應(yīng)用工程檢測信息，對模型的分布參數(shù)和權(quán)重進(jìn)行更新；最后，用更新后的模型參數(shù)和權(quán)重進(jìn)行碳化深度預(yù)測。用一個(gè)10年期自然碳化試驗(yàn)驗(yàn)證了該方法的有效性，并將其用于新華高架橋的耐久性評估。結(jié)果表明該方法可有效提高碳化深度計(jì)算的精確性。 3.提出一種能考慮CO2濃度、溫度隨時(shí)間變化的碳化深度計(jì)算方法。利用最新的氣候變化數(shù)據(jù)和氣候變化預(yù)測模型，研究了CO2濃度升高和氣候變化對碳化深度、鋼筋腐蝕概率、混凝土橋梁表面開裂面積比和承載能力可靠度的影響。結(jié)果表明：CO2排放和氣候變化加速混凝土碳化腐蝕，A1F1和A1B排放策略下混凝土碳化速度分別提高33%和24%左右，A1F1和A1B排放策略下鋼筋開始腐蝕概率和正常使用極限狀態(tài)耐久性失效概率均較氣候不變情形有所提高，其中保護(hù)層質(zhì)量越差，失效概率提高幅度越大。 4.研究了氣候變化對氯鹽環(huán)境下混凝土橋梁耐久性的影響。首先提出一個(gè)計(jì)算混凝土中氯離子擴(kuò)散的新方法，該方法不僅能考慮混凝土摻合料、齡期、溫度、濕度、混凝土與氯離子結(jié)合能力的影響，而且能考慮混凝土結(jié)構(gòu)服役期內(nèi)大氣溫度、大氣濕度和凍融損傷程度的時(shí)變效應(yīng)�？紤]劣化空間變異性特征，研究了A1F1和A1B排放策略對混凝土橋梁耐久性的影響。結(jié)果表明：（1）未來40年，A1F1和A1B排放策略比氣候不變情形的銹蝕開裂比例分別提高15%和12%，嚴(yán)重銹蝕開裂比例分別提高19%和14%；（2）對完好混凝土橋梁，不同截面的失效具有高度相關(guān)性，，其體系可靠度可由關(guān)鍵截面如跨中截面的可靠度代替，而對劣化的鋼筋混凝土梁，應(yīng)考慮鋼筋銹蝕的空間變異性。 5.基于等超越概率原則，根據(jù)混凝土橋梁的預(yù)期使用壽命和拓寬前既有橋梁使用年限，分析了拓寬混凝土橋梁的設(shè)計(jì)基準(zhǔn)期、車輛荷載和設(shè)計(jì)人群的取值�？紤]混凝土橋梁拼寬后新、舊組合結(jié)構(gòu)的不同步劣化引起的橫向分布系數(shù)時(shí)變性，建立了拓寬后新、舊橋梁的時(shí)變可靠性模型。以一座16m跨預(yù)應(yīng)力混凝土簡支梁橋拼寬鋼筋混凝土簡支梁橋?yàn)槔_展研究，結(jié)果表明：（1）拓寬降低原橋的橫向分布系數(shù)，提高老橋的時(shí)變可靠度；（2）原橋鋼筋銹蝕后剛度下降，引起老橋橫向分布系數(shù)均值變小，新橋橫向分布系數(shù)均值變大，新橋和老橋的荷載橫向分布系數(shù)變異系數(shù)均變大；（3）如考慮橫向分布系數(shù)相對變化，老橋的時(shí)變可靠度略有上升，而新橋的時(shí)變可靠度指標(biāo)顯著下降。
[Abstract]:Concrete bridges are the dominant types of highway and urban bridges.Due to the factors of material itself and environment, there are often various durability problems and periodic maintenance is necessary.Due to the complexity of practical engineering problems, the durability evaluation and life prediction of concrete structures will encounter a large number of random, fuzzy and so on. There is no ideal method for durability assessment and life prediction of concrete bridges with incomplete information. On the basis of reviewing relevant literatures at home and abroad, the following researches are carried out on durability of concrete bridges:
1. A group evaluation method for durability of Concrete Bridges Based on AHP and Evidence Theory is proposed. Firstly, the whole bridge is divided into three parts: superstructure, substructure and deck system, and further divided into a series of components and components. Secondly, the determination of index weight at each level and the evaluation of durability of the underlying index. The individual weights of experts are determined by the fuzzy distance between the individual evaluation results and the ideal results. Then, the evaluation opinions of experts are weighted and averaged to obtain the evaluation opinions of the expert group. Finally, the evidence synthesis theory is used to evaluate from the bottom, layer by layer, until the final evaluation results are obtained. The method is used to evaluate Tianpingling Bridge on Guangqing Expressway and Changning River Estuary Bridge in Hunan Province, and the feasibility of the method is verified.
2. On the basis of summarizing and analyzing the existing carbonation models of concrete structures, a Bayesian updating method is proposed to predict the carbonation depth. Firstly, several carbonation models are selected and weighted equally, and the weighted average is used as a prior model to predict the carbonation depth. Then, the distribution parameters and weights of the models are calculated by using the engineering detection information. Finally, the updated model parameters and weights are used to predict the depth of carbonization. A 10-year natural carbonization test is carried out to verify the effectiveness of the proposed method and is used to evaluate the durability of Xinhua viaduct.
3. A method of calculating the depth of carbonation considering the variation of CO2 concentration and temperature with time is proposed. The effects of CO2 concentration and climate change on the depth of carbonation, corrosion probability of steel bars, cracking area ratio of concrete bridge surface and reliability of bearing capacity are studied by using the latest climate change data and climate change prediction model. CO2 emission and climate change accelerated concrete carbonation corrosion. The carbonation rate of concrete under A1F1 and A1B emission strategies increased by 33% and 24% respectively. The corrosion probability of reinforcing bars under A1F1 and A1B emission strategies and the durability failure probability under normal service limit state were both higher than those under the same climate. The worse the quality of protective layer, the worse the failure rate. The greater the probability is.
4. The effect of climate change on the durability of concrete bridges in chloride environment is studied. A new method for calculating chloride ion diffusion in concrete is proposed. This method can not only consider the influence of concrete admixture, age, temperature, humidity, and the binding capacity of concrete to chloride ion, but also consider the atmospheric temperature of concrete structures in service. Considering the spatial variability of deterioration, the effects of A1F1 and A1B emission strategies on the durability of concrete bridges are studied. The results show that: (1) In the next 40 years, A1F1 and A1B emission strategies will increase the corrosion cracking ratio by 15% and 12% respectively, and the severe corrosion cracking ratio will increase by 12%. (2) For intact concrete bridges, the failure of different sections is highly correlated, and the reliability of the system can be replaced by the reliability of key sections such as midspan section, while for deteriorated reinforced concrete beams, the spatial variability of reinforcement corrosion should be considered.
5. Based on the principle of equal transcendence probability, according to the expected service life of concrete bridges and the service life of existing bridges before widening, the design reference period of widening concrete bridges, vehicle loads and design crowd values are analyzed. The time-varying reliability model of new and old bridges after widening is established. Taking a 16m span prestressed concrete simply-supported beam bridge as an example, the results show that: (1) widening reduces the lateral distribution coefficient of the original bridge, and improves the time-varying reliability of the old bridge; (2) the stiffness of the original bridge decreases after corrosion of steel bars, which leads to the lateral reduction of the old bridge. The mean value of the distribution coefficient decreases, the mean value of the lateral distribution coefficient of the new bridge increases, and the variation coefficient of the load lateral distribution coefficient of the new bridge and the old bridge increases. (3) Considering the relative change of the lateral distribution coefficient, the time-varying reliability of the old bridge rises slightly, while the time-varying reliability index of the new bridge decreases significantly.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：U446
本文編號：2196960
[Abstract]:Concrete bridges are the dominant types of highway and urban bridges.Due to the factors of material itself and environment, there are often various durability problems and periodic maintenance is necessary.Due to the complexity of practical engineering problems, the durability evaluation and life prediction of concrete structures will encounter a large number of random, fuzzy and so on. There is no ideal method for durability assessment and life prediction of concrete bridges with incomplete information. On the basis of reviewing relevant literatures at home and abroad, the following researches are carried out on durability of concrete bridges:
1. A group evaluation method for durability of Concrete Bridges Based on AHP and Evidence Theory is proposed. Firstly, the whole bridge is divided into three parts: superstructure, substructure and deck system, and further divided into a series of components and components. Secondly, the determination of index weight at each level and the evaluation of durability of the underlying index. The individual weights of experts are determined by the fuzzy distance between the individual evaluation results and the ideal results. Then, the evaluation opinions of experts are weighted and averaged to obtain the evaluation opinions of the expert group. Finally, the evidence synthesis theory is used to evaluate from the bottom, layer by layer, until the final evaluation results are obtained. The method is used to evaluate Tianpingling Bridge on Guangqing Expressway and Changning River Estuary Bridge in Hunan Province, and the feasibility of the method is verified.
2. On the basis of summarizing and analyzing the existing carbonation models of concrete structures, a Bayesian updating method is proposed to predict the carbonation depth. Firstly, several carbonation models are selected and weighted equally, and the weighted average is used as a prior model to predict the carbonation depth. Then, the distribution parameters and weights of the models are calculated by using the engineering detection information. Finally, the updated model parameters and weights are used to predict the depth of carbonization. A 10-year natural carbonization test is carried out to verify the effectiveness of the proposed method and is used to evaluate the durability of Xinhua viaduct.
3. A method of calculating the depth of carbonation considering the variation of CO2 concentration and temperature with time is proposed. The effects of CO2 concentration and climate change on the depth of carbonation, corrosion probability of steel bars, cracking area ratio of concrete bridge surface and reliability of bearing capacity are studied by using the latest climate change data and climate change prediction model. CO2 emission and climate change accelerated concrete carbonation corrosion. The carbonation rate of concrete under A1F1 and A1B emission strategies increased by 33% and 24% respectively. The corrosion probability of reinforcing bars under A1F1 and A1B emission strategies and the durability failure probability under normal service limit state were both higher than those under the same climate. The worse the quality of protective layer, the worse the failure rate. The greater the probability is.
4. The effect of climate change on the durability of concrete bridges in chloride environment is studied. A new method for calculating chloride ion diffusion in concrete is proposed. This method can not only consider the influence of concrete admixture, age, temperature, humidity, and the binding capacity of concrete to chloride ion, but also consider the atmospheric temperature of concrete structures in service. Considering the spatial variability of deterioration, the effects of A1F1 and A1B emission strategies on the durability of concrete bridges are studied. The results show that: (1) In the next 40 years, A1F1 and A1B emission strategies will increase the corrosion cracking ratio by 15% and 12% respectively, and the severe corrosion cracking ratio will increase by 12%. (2) For intact concrete bridges, the failure of different sections is highly correlated, and the reliability of the system can be replaced by the reliability of key sections such as midspan section, while for deteriorated reinforced concrete beams, the spatial variability of reinforcement corrosion should be considered.
5. Based on the principle of equal transcendence probability, according to the expected service life of concrete bridges and the service life of existing bridges before widening, the design reference period of widening concrete bridges, vehicle loads and design crowd values are analyzed. The time-varying reliability model of new and old bridges after widening is established. Taking a 16m span prestressed concrete simply-supported beam bridge as an example, the results show that: (1) widening reduces the lateral distribution coefficient of the original bridge, and improves the time-varying reliability of the old bridge; (2) the stiffness of the original bridge decreases after corrosion of steel bars, which leads to the lateral reduction of the old bridge. The mean value of the distribution coefficient decreases, the mean value of the lateral distribution coefficient of the new bridge increases, and the variation coefficient of the load lateral distribution coefficient of the new bridge and the old bridge increases. (3) Considering the relative change of the lateral distribution coefficient, the time-varying reliability of the old bridge rises slightly, while the time-varying reliability index of the new bridge decreases significantly.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：U446
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 張偉平,張譽(yù);一般大氣環(huán)境條件下混凝土中鋼筋開始銹蝕時(shí)間的預(yù)測[J];四川建筑科學(xué)研究;2002年01期
2 王春芬;牛荻濤;;鋼筋混凝土鐵路橋梁碳化壽命預(yù)測[J];四川建筑科學(xué)研究;2006年03期
3 張建仁;吳曉俊;王磊;;銹蝕率對同類型RC梁抗彎剛度影響[J];長沙交通學(xué)院學(xué)報(bào);2008年03期
4 余紅發(fā);孫偉;;混凝土氯離子擴(kuò)散理論模型[J];東南大學(xué)學(xué)報(bào)(自然科學(xué)版);2006年S2期
5 孔啟明;弓國軍;楊娟娟;宋曉冰;;氯鹽環(huán)境下混凝土鋼筋腐蝕速度實(shí)用公式[J];低溫建筑技術(shù);2006年03期
6 索清輝,錢永久,張方;對公路橋梁剩余壽命評估時(shí)可變荷載取值的研究[J];中國工程科學(xué);2004年05期
7 秦權(quán);賀瑞;楊小剛;;在時(shí)變結(jié)構(gòu)可靠度領(lǐng)域中有必要澄清一個(gè)錯(cuò)誤概念[J];工程力學(xué);2009年08期
8 孟波,付微;一種有限方案多目標(biāo)群決策方法[J];系統(tǒng)工程;1998年04期
9 黃萍;;福州馬尾互通匝道橋拼寬對舊橋的影響分析[J];工程與建設(shè);2008年02期
10 張建仁,王存立;在用鋼筋混凝土梁橋耐久性的模糊評定[J];公路交通科技;2005年04期
本文編號：2196960
本文鏈接：http://sikaile.net/kejilunwen/jiaotonggongchenglunwen/2196960.html
最近更新
教材專著
