本文選題：橋梁加固 + 結(jié)構(gòu)預(yù)應(yīng)力　； 參考：《西南交通大學(xué)》2015年博士論文

【摘要】：橋梁加固時(shí),新舊材料的應(yīng)力差(可能是新材料的應(yīng)力滯后或應(yīng)力超前)是最為常見(jiàn)又必須考慮的技術(shù)難題。如何讓新舊材料均衡、合理地參與結(jié)構(gòu)(或截面)受力,即如何有效、便捷地解決新舊材料的應(yīng)力差是不少橋梁加固工作者面臨的一個(gè)關(guān)鍵問(wèn)題。為解決此問(wèn)題,橋梁加固逐漸形成由被動(dòng)加固向主動(dòng)加固、由單一加固方法向綜合加固法(各種單一加固方法的聯(lián)合使用)發(fā)展的趨勢(shì)。本文以此為出發(fā)點(diǎn),通過(guò)模型試驗(yàn)、理論分析、以及現(xiàn)場(chǎng)試驗(yàn),主要完成了以下五個(gè)方面內(nèi)容：1、在預(yù)彎預(yù)應(yīng)力思想的基礎(chǔ)上,結(jié)合加固橋梁新舊材料分階段受力的特點(diǎn),本文分析并定義了“結(jié)構(gòu)預(yù)應(yīng)力”。并在此基礎(chǔ)上,系統(tǒng)提出了結(jié)構(gòu)預(yù)應(yīng)力綜合加固法的核心思想和內(nèi)容。同時(shí),基于橋梁加固設(shè)計(jì)的目的及基本原則,詳細(xì)分析了該方法的優(yōu)點(diǎn)和適用性。并基于病危橋梁現(xiàn)狀,詳細(xì)分析了該方法的必要性。2、通過(guò)3組鋼筋混凝土梁的模型試驗(yàn)以及擴(kuò)展有限元分析,研究了不同卸載水平下加固混凝土梁的極限荷載、應(yīng)力變形情況、破壞機(jī)理,以及卸載率對(duì)加固混凝土梁極限荷載、破壞模式的影響。研究表明：在不同卸載率(意義類似“預(yù)應(yīng)力度”,表征預(yù)應(yīng)力施加大小程度,定義詳見(jiàn)第2章)條件下進(jìn)行加固的鋼筋混凝土梁,在受載過(guò)程中混凝土與鋼筋應(yīng)力分布差異極大,導(dǎo)致加固鋼筋混凝土梁正常使用的承載力存在顯著差異,但其極限承載能力差異不大；對(duì)加固混凝土梁承載力進(jìn)行計(jì)算時(shí)必須分階段進(jìn)行計(jì)算以考慮卸載率的影響；采用擴(kuò)展有限元分析能較為準(zhǔn)確地模擬鋼筋混凝土梁的受力行為與開(kāi)裂過(guò)程,可以作為鋼筋混凝土梁力學(xué)性能分析的有效手段。3、定義了基于兩種不同極限狀態(tài)考慮的最佳初始彎矩及對(duì)應(yīng)的最佳卸載率；并分析和設(shè)定了兩種極限狀態(tài)下最佳初始彎矩應(yīng)滿足的條件。依據(jù)設(shè)定的條件及相應(yīng)的假定,推導(dǎo)和建立了基于兩種極限狀態(tài)考慮的最佳初彎矩的求解公式,進(jìn)而即可確定在適宜的加固參數(shù)條件下的最佳卸載率。同時(shí),給出了在初彎矩確定的情況下最佳加固層厚度的求解公式。在此過(guò)程中,也詳細(xì)分析了加固層厚度與最佳初始彎矩的相互關(guān)系。同時(shí),提出了受彎構(gòu)件加固設(shè)計(jì)流程及應(yīng)重點(diǎn)關(guān)注的問(wèn)題。4、系統(tǒng)分析并提出了結(jié)構(gòu)預(yù)應(yīng)力綜合法需考慮的關(guān)鍵因素,主要是擬加固橋梁現(xiàn)狀分析和橋梁結(jié)構(gòu)受力特點(diǎn)分析。在此基礎(chǔ)上,分析并提出了結(jié)構(gòu)預(yù)應(yīng)力綜合加固法的要點(diǎn)。即應(yīng)遵循相應(yīng)的安全原則、選擇合理的卸載方向、合理選擇加固順序(需要時(shí))。針對(duì)拱橋、簡(jiǎn)支混凝土梁橋等卸載難度較大的橋梁,提出了一系列簡(jiǎn)單、有效的卸載(預(yù)應(yīng)力施加方法)工程措施,為結(jié)構(gòu)預(yù)應(yīng)力綜合加固法的工程應(yīng)用提供了相應(yīng)的技術(shù)支撐。5、結(jié)合具體維修加固工程實(shí)例,對(duì)采用影響線原理進(jìn)行卸載的結(jié)構(gòu)預(yù)應(yīng)力綜合加固法的應(yīng)用進(jìn)行了研究。研究結(jié)果表明：在以本文的研究成果為基礎(chǔ)進(jìn)行橋梁加固工程中,新、舊混凝土應(yīng)力分布合理、加固后承載力儲(chǔ)備較高；加固達(dá)到了預(yù)期的效果,且該方法加固效果明顯,并具有較強(qiáng)的可操作性。
[Abstract]:The bridge reinforcement, the stress difference between the old and new materials (possibly new material stress lag or stress in advance) is the most common technical problem. It must consider how to make new material balance, reasonable in structure (or section) force, namely how to effectively, easily solve the problem of stress of old and new materials the difference is a key problem facing many bridge workers. In order to solve this problem, the bridge reinforcement formed gradually from passive to active reinforcement reinforcement to comprehensive reinforcement method by single reinforcement method (using a combination of various single reinforcement methods) development trend. This article as a starting point, through the model experiment, theoretical analysis well, the field test, the following five aspects: 1, based on the pre bending prestressed idea, combined with the characteristics of stage loading bridge reinforcement of old and new materials, this paper analyzes and defines the structure and prestress. On the basis of this, put forward system structure of prestressed comprehensive strengthening core idea and content of law. At the same time, the bridge reinforcement design objectives and basic principles based on the detailed analysis of the advantages and applicability of the method. And based on the detailed analysis of the present situation of the bridge was dying, the necessity of.2, through the model test of 3 reinforced group concrete beam and extended finite element analysis of the ultimate load of reinforced concrete beams under different unloading stress, deformation, failure mechanism, and the unloading rate of reinforced concrete beams with the ultimate load, the failure mode of the influence. The study shows that under different unloading rate (meaning similar degree of prestress, prestressed characterization applied degree, defined in chapter second) under the condition of reinforced concrete beams, in the loading process of concrete and steel bar stress distribution varies greatly, leading to the reinforcement of reinforced concrete Liang Zheng The bearing capacity of commonly used the existence of significant differences, but the difference of ultimate bearing capacity; reinforcement bearing capacity calculation must be calculated by considering the influence of the unloading rate of concrete beam; using extended finite element analysis can accurately simulate the reinforced concrete beam under stress and cracking behavior of.3 can be used as effective means. Mechanical properties of the reinforced concrete beam analysis, defined the best unloading optimal initial moment and corresponding to two different limit states considered based on the rate; and analysis and set up two kinds of limit state optimal initial moment condition. According to the conditions set and the corresponding assumptions, established and deduced formula two limit consider the best state based on the initial moment, which can be determined in the appropriate reinforcement parameters under the conditions of the best unloading rate. At the same time, are identified in the initial moment The best formula of thickness of reinforcing layer under the circumstances. In this process, also analyzed the relationship between consolidation layer thickness and the best initial moment. At the same time, put forward by strengthening design process and should focus on the problem of.4 bending, system analysis and put forward the key factors influencing the structure of pre stress method should be considered that is mainly intends to analyze the stress characteristics of bridge structure analysis and reinforcement of bridge status. On the basis of analysis, and put forward the structure of prestressed reinforcement method. The comprehensive points should follow the corresponding principle of safety, choose reasonable unloading direction, reasonable choice of reinforcement order (when necessary). For the arch bridge, the bridge simply supported concrete beams bridge unloading difficult, put forward a series of simple and effective unloading (prestressing method) engineering measures for prestressed structure comprehensive reinforcement engineering application method to provide the corresponding technical support.5, Combined with the specific maintenance and reinforcement project, the influence of prestressed structure principle of unloading line comprehensive reinforcement method application are studied. The results show that: in this research as the basis for the bridge reinforcement project, the new and old concrete stress distribution is reasonable, high bearing capacity reserves after reinforcement; reinforcement to the expected effect, and the reinforcement effect is obvious, and has strong operability.

【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U445.72

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