發(fā)布時間：2018-04-30 14:11

  本文選題：預(yù)應(yīng)力混凝土箱梁 + 火災(zāi)��； 參考：《長安大學》2014年博士論文

【摘要】：近年來，隨著交通量的迅猛增加以及運輸工具的多樣性，橋梁火災(zāi)事故頻頻發(fā)生，運輸易燃易爆物品的車輛日漸增多，交通事故和人為原因引起的橋梁火災(zāi)成為交通基礎(chǔ)設(shè)施新的威脅�；馂�(zāi)作為橋梁的偶然荷載，對結(jié)構(gòu)造成不可估量的破壞，輕者勢必影響交通質(zhì)量，造成人身傷亡和經(jīng)濟損失，重者可造成橋梁永久破壞與坍塌。目前關(guān)于橋梁火災(zāi)的研究主要集中在火災(zāi)下預(yù)應(yīng)力混凝土（以下簡稱“PSC”）結(jié)構(gòu)及鋼筋混凝土（以下簡稱“RC”）結(jié)構(gòu)整體及局部抗火性能，涉及火災(zāi)后RC整體及局部抗火性能較少，對于火災(zāi)后PSC結(jié)構(gòu)的抗火性能研究更少。 本文以國家自然科學基金“火災(zāi)下混凝土橋梁有效預(yù)應(yīng)力衰變機理與承載能力分析方法研究（51308056）”；交通運輸部交通建設(shè)科技項目“火災(zāi)下橋梁結(jié)構(gòu)災(zāi)變機理及安全性評價與加固技術(shù)研究（2011318812970）”為依托，針對預(yù)應(yīng)力混凝土箱型梁橋整體抗火性能，以模型試驗結(jié)合數(shù)值模擬進行了系統(tǒng)研究。主要研究工作有： 基于各規(guī)范、學者的調(diào)研，對高溫作用后預(yù)應(yīng)力混凝土材料的強度、彈性模量及本構(gòu)關(guān)系進行計算模型的整理與分析，并對使用率高的計算模型進行分階段選取、分布擬合的方法獲得高溫作用后預(yù)應(yīng)力混凝土材料各力學性能指標（強度、彈性模量及本構(gòu)關(guān)系）的擬合計算模型。 對3片試驗梁（對比梁PSB-1、無防火涂層試驗梁PSB-2、有防火涂層試驗梁PSB-3）進行火災(zāi)下及火災(zāi)后的模型試驗研究�；诨馂�(zāi)下試驗梁的溫度場、位移時程及預(yù)應(yīng)力損失等數(shù)據(jù)分析，揭示了防護涂層對PSC結(jié)構(gòu)抗火性能的影響程度�；诨馂�(zāi)后試驗梁的位移、應(yīng)變及剛度、頻率等數(shù)據(jù)分析，給出了PSC結(jié)構(gòu)火災(zāi)后的剩余承載能力及動力特性狀況。 通過測定混凝土試塊高溫后的抗壓強度，并對比未受高溫的試塊，研究了膨脹型防火涂料不同厚度對混凝土結(jié)構(gòu)的防火保護作用，給出了強度折減的經(jīng)驗公式。通過對受火梁按由底至頂及燒損深度的方法來測定混凝土強度，計算混凝土強度值，揭示了受火后混凝土強度沿梁高及燒損深度的變化規(guī)律。 研究分析了EUROCODE、ASTM-E119、JISA1304及ISO834等多種火災(zāi)升溫計算模型，明確了火災(zāi)分析采用的升溫模型和理論計算方法，通過對比火災(zāi)過程中結(jié)構(gòu)溫度場的試驗數(shù)據(jù)，揭示了結(jié)構(gòu)溫度場由外至內(nèi)的熱傳導(dǎo)規(guī)律，并運用大型通用軟件建立有限元模型，進行溫度場的非線性分析，通過與實測值對比，驗證了模型的正確性。 運用大型通用有限元分析軟件對3片試驗梁進行模擬，通過設(shè)定材料不同的本構(gòu)關(guān)系，并依照試驗的邊界條件建立有限元模型，，模擬試驗梁在荷載作用下的撓曲變形、混凝土應(yīng)變以及試驗梁的極限承載力、固有頻率等，通過與實測值的對比，驗證了模型的有效性。
[Abstract]:In recent years, with the rapid increase of traffic volume and the diversity of means of transport, bridge fire accidents occur frequently, and the number of vehicles transporting flammable and explosive items is increasing. Traffic accidents and man-made bridge fires have become a new threat to traffic infrastructure. Fire, as the accidental load of bridge, causes inestimable damage to the structure. The lighter is bound to affect the traffic quality, resulting in casualties and economic losses, and the heavy can cause permanent damage and collapse of the bridge. At present, the research on bridge fire mainly focuses on the whole and local fire resistance of prestressed concrete (PSC) structure and reinforced concrete (RC) structure under fire. The overall and local fire resistance of RC structures after fire is less than that of PSC structures after fire. In this paper, the National Natural Science Foundation of China "effective Prestress decay Mechanism and bearing capacity Analysis method of concrete Bridges under Fire" (51308056); Based on the science and technology project of traffic construction of Ministry of Communications and Transport, "study on disaster Mechanism and Safety Evaluation and reinforcement Technology of Bridge structure under Fire", aiming at the overall fire resistance of prestressed concrete box girder bridge, The model test and numerical simulation are used in this paper. The main research work is: Based on various codes and scholars' research, the strength, elastic modulus and constitutive relation of prestressed concrete materials after high temperature action are analyzed and analyzed, and the calculation models with high utilization rate are selected in different stages. The fitting model of mechanical properties (strength, elastic modulus and constitutive relation) of prestressed concrete after high temperature action was obtained by the method of distribution fitting. The model tests of three test beams (PSB-1, PSB-2 and PSB-3) were carried out under fire and after fire. Based on the analysis of the temperature field, displacement time history and prestress loss of the test beam under fire, the influence of the protective coating on the fire resistance of PSC structure is revealed. Based on the analysis of the displacement, strain, stiffness and frequency of the test beam after fire, the residual bearing capacity and dynamic characteristics of the PSC structure after fire are given. By measuring the compressive strength of concrete specimens after high temperature and comparing the unheated specimens, the fire protection effects of different thickness of expansive fire resistant coatings on concrete structures are studied, and the empirical formula of strength reduction is given. The concrete strength was measured by the method of bottom to top and burning depth of fire beam, and the concrete strength value was calculated. The variation rule of concrete strength along the beam height and burning depth after fire was revealed. Several fire heating calculation models, such as EUROCODEN ASTM-E119JISA1304 and ISO834, are studied and analyzed. The heating model and theoretical calculation method used in fire analysis are defined. The experimental data of structure temperature field during fire are compared. The heat conduction law of the structure temperature field from outside to inside is revealed, and the finite element model is established by using a large scale general software, and the nonlinear analysis of the temperature field is carried out. The correctness of the model is verified by comparing with the measured data. Three test beams are simulated by using a large and universal finite element analysis software. By setting up different constitutive relations of materials and establishing a finite element model according to the boundary conditions of the test, the flexural deformation of the test beams under load is simulated. The concrete strain and the ultimate bearing capacity and natural frequency of the test beam are compared with the measured values to verify the validity of the model.
【學位授予單位】：長安大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U447;U441

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