【摘要】：工程中,既有橋梁結(jié)構(gòu)的損傷評(píng)估與加固分析多采用試驗(yàn)測(cè)試或基準(zhǔn)有限元建模分析,存在局限性。尤其是建立有限元模型時(shí),要對(duì)真實(shí)結(jié)構(gòu)做各種假設(shè),使得有限元模型與實(shí)際結(jié)構(gòu)存在誤差,計(jì)算值和試驗(yàn)測(cè)量值不能很好的一致,這給橋梁的狀態(tài)評(píng)估、剩余壽命的預(yù)測(cè)增加了困難。故如何修正有限元模型,改善既有結(jié)構(gòu)的建模精度,一直是研究的熱點(diǎn)。目前比較公認(rèn)的和可行的方法是利用計(jì)算機(jī)技術(shù)把實(shí)驗(yàn)測(cè)試結(jié)果與計(jì)算機(jī)仿真集成進(jìn)行有限元修正�；诖�,本文嘗試建立ANSYS平臺(tái)的結(jié)構(gòu)初始有限元模型,結(jié)合實(shí)橋結(jié)構(gòu)試驗(yàn)測(cè)試結(jié)果,對(duì)結(jié)構(gòu)參數(shù)進(jìn)行靈敏度分析得到主要修正參數(shù),借助ANSYS優(yōu)化模塊中一階搜索優(yōu)化理論的結(jié)構(gòu)參數(shù)估計(jì)技術(shù),對(duì)結(jié)構(gòu)的初始有限元模型進(jìn)行策略性修正。研究比較了不同有限元修正技術(shù)的可行性及有效性,并將修正后的有限元模型作為基準(zhǔn)模型應(yīng)用于既有預(yù)應(yīng)力實(shí)橋的承載力評(píng)估與加固分析。結(jié)果表明,文述方法可以用于既有預(yù)應(yīng)力橋梁結(jié)構(gòu)的健康狀態(tài)評(píng)估。主要工作如下:1.以某運(yùn)營(yíng)多年的實(shí)橋?yàn)楣こ桃劳?運(yùn)用載荷試驗(yàn)方法,對(duì)結(jié)構(gòu)主梁和主要的連系構(gòu)件進(jìn)行了全面的檢測(cè),通過(guò)靜載試驗(yàn)、動(dòng)載試驗(yàn)等手段獲取橋梁的基本靜動(dòng)力特性。根據(jù)現(xiàn)場(chǎng)初步損傷診斷結(jié)果分析得到的直接損傷信息,為用ANSYS平臺(tái)建立損傷有限元數(shù)值模型提供了數(shù)據(jù)依據(jù)。2.依據(jù)實(shí)橋檢測(cè)結(jié)果,建立其參數(shù)化有限元模型,嘗試采用具有針對(duì)性的修正策略借助一階搜索優(yōu)化的算法,對(duì)試驗(yàn)段構(gòu)件分別進(jìn)行了基于靜力測(cè)試、動(dòng)力測(cè)試以及聯(lián)合應(yīng)用靜動(dòng)力測(cè)試數(shù)據(jù)的有限元模型修正。比較了不同方法的模型修正效率和效果,介紹了優(yōu)化方法的選擇,并指出有限元模型修正是一個(gè)針對(duì)性很強(qiáng)的技術(shù),幾乎沒(méi)有一種普適的算法進(jìn)行修正,因而對(duì)于不同類型的工程結(jié)構(gòu)應(yīng)發(fā)展出相應(yīng)合適的修正方法,盡可能獲得相對(duì)準(zhǔn)確的修正模型。3.考慮到既有大跨徑預(yù)應(yīng)力混凝土橋梁的力學(xué)特性比一般結(jié)構(gòu)受更多因素的影響,修正參數(shù)的選取人工干預(yù)較大,使得傳統(tǒng)有限元修正結(jié)果的穩(wěn)定性和適用性較差,本文利用蟻群優(yōu)化算法在解決復(fù)雜的、不確定性及非線性等問(wèn)題的優(yōu)勢(shì),嘗試引入基于蟻群算法的有限元模型修正。結(jié)果表明,該模型是有效的,從而為工程中的大型結(jié)構(gòu)的有限元模型修正提供了新的思路。4.依托既有預(yù)應(yīng)力混凝土實(shí)橋,將修正后的有限元模型作為基準(zhǔn)模型,對(duì)其承載力進(jìn)行狀態(tài)評(píng)估,表明修正后的有限元模型能夠比較準(zhǔn)確的反映橋梁的實(shí)際受力狀態(tài),可以用于既有預(yù)應(yīng)力混凝土橋梁結(jié)構(gòu)的損傷評(píng)估與識(shí)別。在此基礎(chǔ)上,對(duì)結(jié)構(gòu)損傷嚴(yán)重的部位提出了加固方案,建立了加固后的有限元模型,比較加固前后的承載力,驗(yàn)證了加固方法的有效性。
[Abstract]:In the engineering, the damage assessment and reinforcement analysis of existing bridge structures are usually carried out by means of test or benchmark finite element modeling analysis, which has some limitations. Especially when establishing the finite element model, we should make various assumptions about the real structure, which make the finite element model and the actual structure have errors, the calculated value and the experimental measurement value can not be in good agreement, which gives the bridge state evaluation. Prediction of residual life increases difficulties. Therefore, how to modify the finite element model and improve the modeling accuracy of existing structures has been a hot topic. At present, the widely accepted and feasible method is to use computer technology to integrate the experimental results with computer simulation to modify the finite element method. Based on this, this paper attempts to establish the initial finite element model of the structure of ANSYS platform. Combined with the test results of the real bridge structure, the main modified parameters are obtained by the sensitivity analysis of the structural parameters. With the help of the first-order search optimization theory in ANSYS optimization module, the structure parameter estimation technique is used to modify the initial finite element model of the structure strategically. The feasibility and effectiveness of different finite element modification techniques are studied and compared, and the modified finite element model is used as the benchmark model to evaluate the bearing capacity and strengthen the existing prestressed bridge. The results show that the method can be used to evaluate the health status of existing prestressed bridge structures. The main work is as follows: 1. Based on a real bridge which has been in operation for many years, the basic static and dynamic characteristics of the bridge are obtained by means of static load test and dynamic load test. According to the direct damage information obtained from the analysis of the field preliminary damage diagnosis results, this paper provides a data basis for the establishment of the damage finite element numerical model based on the ANSYS platform. Based on the test results of real bridge, the parametric finite element model is established, and the static test of the components of the test section is carried out based on the first order search optimization algorithm. Dynamic test and finite element model modification for combined application of static and dynamic test data. This paper compares the efficiency and effect of model modification with different methods, introduces the selection of optimization methods, and points out that the finite element model modification is a highly targeted technique, and almost no universal algorithm is used to modify it. Therefore, it is necessary to develop appropriate correction methods for different types of engineering structures, and to obtain as far as possible a relatively accurate correction model .3. Considering that the mechanical properties of existing long-span prestressed concrete bridges are affected by more factors than those of general structures, the selection of modification parameters is more important, which makes the stability and applicability of the traditional finite element correction worse. Based on the advantages of ant colony optimization in solving complex, uncertain and nonlinear problems, this paper attempts to introduce a finite element model modification based on ant colony algorithm. The results show that the model is effective and provides a new idea for the finite element model modification of large structures in engineering. Based on the existing prestressed concrete bridge, the modified finite element model is used as the benchmark model to evaluate the bearing capacity of the bridge, which shows that the modified finite element model can accurately reflect the actual stress state of the bridge. It can be used for damage assessment and identification of existing prestressed concrete bridge structures. On this basis, the reinforcement scheme is proposed for the severely damaged parts of the structure, and the finite element model after strengthening is established. The bearing capacity before and after reinforcement is compared, and the effectiveness of the reinforcement method is verified.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U441;U448.35

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