本文選題：預(yù)應(yīng)力CFRP　切入點(diǎn)：力學(xué)性能　出處：《湖南大學(xué)》2014年博士論文

【摘要】：預(yù)應(yīng)力CFRP加固鋼筋混凝土結(jié)構(gòu)技術(shù)能夠較充分地利用CFRP的高強(qiáng)性能,改善被加固結(jié)構(gòu)在工作階段的使用性能,因此近年來得到了廣泛的關(guān)注,眾多學(xué)者開展了大量研究工作。但這些工作大多集中于預(yù)應(yīng)力CFRP加固混凝土結(jié)構(gòu)的受力性能,并且所用試件的尺寸往往較小,與真實(shí)結(jié)構(gòu)存在一定差距。作為一種新型技術(shù)加固的結(jié)構(gòu),預(yù)應(yīng)力CFRP加固的混凝土結(jié)構(gòu)其在溫度、凍融等環(huán)境因素作用下工作性能隨時(shí)間變化的規(guī)律仍有待進(jìn)一步認(rèn)識。因此,本文針對預(yù)應(yīng)力CFRP板加固混凝土結(jié)構(gòu)的力學(xué)性能及溫差與凍融影響開展了系統(tǒng)性的研究工作,包括： (1)通過模型試驗(yàn)研究,系統(tǒng)考察了預(yù)應(yīng)力CFRP加固大尺寸混凝土構(gòu)件的力學(xué)性能：對比了非預(yù)應(yīng)力FRP、預(yù)應(yīng)力FRP加固梁的力學(xué)性能差異；分析了設(shè)計(jì)參數(shù)對加固橋梁受力性能的影響；探討了初始應(yīng)力、粘結(jié)性能等引起的加固橋梁破壞形態(tài)的演變規(guī)律及內(nèi)在機(jī)理；提出了加固結(jié)構(gòu)承載能力、剛度等的設(shè)計(jì)計(jì)算公式。 (2)通過加固實(shí)橋的現(xiàn)場長期監(jiān)測研究,系統(tǒng)考察了溫度作用下預(yù)應(yīng)力CFRP板加固混凝土橋梁的力學(xué)性能：通過對已加固橋梁預(yù)應(yīng)力CFRP板應(yīng)變及梁頂、梁底溫度變化的晝夜觀測,在平截面等假設(shè)基礎(chǔ)上,將溫度變化下的混凝土應(yīng)變按產(chǎn)生的原因分為溫度自由應(yīng)變、自約束應(yīng)變和外約束應(yīng)變,利用疊加原理推導(dǎo)得到了預(yù)應(yīng)力CFRP板溫度應(yīng)變的計(jì)算公式。 (3)系統(tǒng)研究了凍融循環(huán)作用下預(yù)應(yīng)力CFRP板加固鋼筋混凝土梁的受力性能變化規(guī)律,探索了凍融循環(huán)和預(yù)應(yīng)力水平對加固梁破壞形態(tài)、承載能力等的影響,并深入分析了凍融循環(huán)次數(shù)、混凝土強(qiáng)度、初始應(yīng)力大小等影響因素對凍融環(huán)境下碳纖維片材-混凝土界面粘結(jié)性能的影響規(guī)律,明確了預(yù)應(yīng)力碳纖維加固混凝土結(jié)構(gòu)在凍融侵蝕環(huán)境下退化機(jī)理,提出了預(yù)應(yīng)力CFRP加固鋼筋混凝土梁的承載能力隨凍融循環(huán)作用的計(jì)算模型。 (4)通過試驗(yàn)研究考察了CFRP-混凝土的界面粘結(jié)極限承載力、界面應(yīng)力分布等界面粘結(jié)性能,分析了粘結(jié)長度等因素對界面粘結(jié)性能的影響；在試驗(yàn)研究基礎(chǔ)上,建立了CFRP-混凝土界面粘結(jié)的有限元分析模型,通過有限元分析提出了界面粘結(jié)-滑移本構(gòu)關(guān)系的擬合方法,比較了本文試驗(yàn)結(jié)果與目前主要幾種粘結(jié)滑移本構(gòu)關(guān)系的吻合程度,得到了符合本文試驗(yàn)的CFRP-混凝土界面粘結(jié)滑移本構(gòu)模型。
[Abstract]:The reinforced concrete structure strengthened by prestressed CFRP can make full use of the high strength performance of CFRP and improve the performance of the strengthened structure in the working stage, so it has been paid more and more attention in recent years. Many scholars have carried out a lot of research work, but most of these work focus on the mechanical behavior of concrete structures strengthened by prestressed CFRP, and the size of the specimens used is often smaller. There is a certain gap between the structure and the real structure. As a new type of structure strengthened by technology, the working performance of prestressed CFRP reinforced concrete structure under the action of temperature, freeze-thaw and other environmental factors still needs to be further understood. In this paper, the mechanical properties, temperature difference and freeze-thaw effects of prestressed CFRP slab reinforced concrete structures are studied systematically, including:. 1) the mechanical properties of large-sized concrete members strengthened by prestressed CFRP are systematically investigated through model test. The differences of mechanical properties of non-prestressed CFRP and prestressed FRP strengthened beams are compared. The influence of design parameters on the mechanical behavior of strengthened bridge is analyzed, the evolution law and internal mechanism of the failure form of strengthened bridge caused by initial stress and bond performance are discussed, and the bearing capacity of strengthened bridge is put forward. Design and calculation formula of stiffness etc. 2) the mechanical properties of concrete bridge strengthened by prestressed CFRP slab under the action of temperature are systematically investigated through the long-term monitoring study on the consolidation of the bridge. The strain of prestressed CFRP slab and the temperature change of the top and bottom of the beam are observed day and night through the observation of the strain of the prestressed CFRP slab and the temperature change of the beam bottom of the strengthened bridge. On the basis of the assumption of plane cross section, the concrete strain under temperature change is divided into temperature free strain, self constrained strain and external constrained strain according to the causes. The formula for calculating the temperature strain of prestressed CFRP slab is derived by using the superposition principle. In this paper, the variation of mechanical behavior of reinforced concrete beams strengthened by prestressed CFRP slab under freeze-thaw cycle is systematically studied, and the effects of freeze-thaw cycles and prestress levels on the failure form and bearing capacity of strengthened beams are explored. The influence of the factors such as the times of freeze-thaw cycle, the strength of concrete and the magnitude of initial stress on the interfacial bond properties of carbon fiber sheet and concrete in freeze-thaw environment are analyzed. The degradation mechanism of prestressed carbon fiber reinforced concrete structure under freeze-thaw erosion environment is clarified, and the calculation model of the load-carrying capacity of reinforced concrete beams strengthened by prestressed CFRP with freeze-thaw cycle is put forward. 4) through the experimental study, the interface bond properties of CFRP- concrete such as the ultimate bearing capacity of interface bond, the distribution of interfacial stress, and the influence of bonding length on the interfacial bond properties are investigated, and based on the experimental study, the interfacial bond behavior of CFRP- concrete is studied. The finite element analysis model of CFRP- concrete interface bond is established. Through the finite element analysis, the fitting method of the interface bond-slip constitutive relation is put forward, and the experimental results are compared with the main bond-slip constitutive relations. The bond-slip constitutive model of CFRP-concrete interface is obtained.
【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】：U445.72;U441

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