本文關(guān)鍵詞：大跨度預(yù)應(yīng)力CFRP筋索FRCC受彎構(gòu)件受力性能研究　出處：《東南大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 碳纖維筋 體外預(yù)應(yīng)力 纖維增強(qiáng)水泥基復(fù)合材料 應(yīng)力增量 延性

【摘要】：碳纖維增強(qiáng)復(fù)合材料筋CFRP (Carbon Fiber Reinforced Polymer)筋和纖維增強(qiáng)水泥基復(fù)合材料FRCC (Fiber Reinforced Cement Composite)是土木工程領(lǐng)域的兩種新型高強(qiáng)建筑材料。與普通鋼筋混凝土結(jié)構(gòu)相比,CFRP筋具有輕質(zhì)高強(qiáng)、耐腐蝕、抗疲勞等良好的物理性能,使其能夠代替?zhèn)鹘y(tǒng)的預(yù)應(yīng)力鋼筋作為體外預(yù)應(yīng)力筋的材料,這已成為研究熱點(diǎn)之一。但由于FRP材料和普通的混凝土材料的脆性破壞性能,采用FRP配筋的混凝土結(jié)構(gòu)的延性一般較差,而引入適量鋼纖維的FRCC材料由于其強(qiáng)度高、極限壓應(yīng)變大等特點(diǎn),能夠較好的克服體外預(yù)應(yīng)力CFRP筋混凝土結(jié)構(gòu)這一所固有的缺陷。而且由于該種材料較高的抗拉性能,在提高結(jié)構(gòu)的抗裂度方面能夠發(fā)揮較大作用。采用這兩種新型材料組合而成的體外預(yù)應(yīng)力混凝土結(jié)構(gòu),對(duì)于克服鋼筋的銹蝕實(shí)現(xiàn)混凝土結(jié)構(gòu)的耐久性以及減輕結(jié)構(gòu)自重具有重要的工程價(jià)值,為結(jié)構(gòu)往大跨度方向發(fā)展提供了可能。本文主要采用了不同直徑的國(guó)產(chǎn)光圓CFRP筋和纖維增強(qiáng)水泥基復(fù)合材料,針對(duì)跨高比為20的體外預(yù)應(yīng)力CFRP筋索FRCC受彎構(gòu)件的抗彎性能進(jìn)行了相應(yīng)的試驗(yàn)研究,包括材料性能研究和構(gòu)件力學(xué)性能研究。主要研究?jī)?nèi)容包括：(1)采用本課題組自主研發(fā)的夾片式錨具進(jìn)行了直徑8mm和直徑11mm的兩種國(guó)產(chǎn)光圓CFRP筋的錨具靜載錨固性能試驗(yàn)研究,主要包括CFRP筋的抗拉強(qiáng)度、彈性模量和延伸率的測(cè)量,獲得CFRP筋的應(yīng)力-應(yīng)變關(guān)系曲線。試驗(yàn)表明,本文中的CFRP筋錨具組裝件基本能發(fā)揮出CFRP筋的極限抗拉強(qiáng)度,沒(méi)有出現(xiàn)滑移現(xiàn)象,具有一定的工程實(shí)用價(jià)值。(2)通過(guò)棱柱體和8字模試驗(yàn)研究了纖維增強(qiáng)水泥基復(fù)合材料FRCC的材料性能,主要參數(shù)包括抗拉強(qiáng)度、抗壓強(qiáng)度、彈性模量、極限壓應(yīng)變和極限拉應(yīng)變等,并獲得了相應(yīng)的抗拉和抗壓性能的應(yīng)力—應(yīng)變?nèi)�,基于試驗(yàn)結(jié)果建立了相應(yīng)的FRCC單軸受壓和受拉的本構(gòu)關(guān)系。(3)完成了1根體外預(yù)應(yīng)力CFRP筋普通混凝土梁和5根體外預(yù)應(yīng)力CFRP筋FRCC梁的抗彎性能試驗(yàn)研究。研究的參數(shù)主要有：混凝土類型、CFRP筋直徑和張拉控制力。根據(jù)相應(yīng)的試驗(yàn)結(jié)果和試驗(yàn)現(xiàn)象分析了構(gòu)件的破壞模式,詳細(xì)討論了構(gòu)件的受力過(guò)程、撓度變化、預(yù)應(yīng)力筋的應(yīng)力增量等。同時(shí)針對(duì)不同的參數(shù)將相應(yīng)的構(gòu)件的試驗(yàn)結(jié)果進(jìn)行了對(duì)比,分析了其試驗(yàn)結(jié)果產(chǎn)生差異的原因。試驗(yàn)結(jié)果表明：相同配筋率和預(yù)應(yīng)力度條件下的FRCC梁的極限承載力均要比普通混凝土梁的承載力要高50%左右,且具有更加良好的極限變形能力和延性水平,其延性水平提高35%左右。另外,在正常使用階段,試驗(yàn)梁的裂縫分布形態(tài)及其發(fā)展路徑表明：FRCC梁與普通混凝土梁相比,其裂縫分布呈現(xiàn)出“細(xì)而密”的特點(diǎn),這主要與FRCC的材料特性有關(guān),其含有的鋼纖維能夠抑制裂縫的擴(kuò)展,同時(shí)提供混凝土開(kāi)裂時(shí)的橋接應(yīng)力,使得材料塑性發(fā)展更為充分,裂縫發(fā)展分布比較均勻。(4)在試驗(yàn)研究的基礎(chǔ)上對(duì)體外預(yù)應(yīng)力CFRP筋混凝土構(gòu)件的受力機(jī)理進(jìn)行了理論計(jì)算分析。首先從既有的體外預(yù)應(yīng)力筋的應(yīng)力增量的計(jì)算方法揭示了其受力機(jī)理,包括粘結(jié)折減系數(shù)法、基于塑性鉸理論的計(jì)算方法、基于截面配筋綜合指標(biāo)的方法等。然后根據(jù)Pannel模型并結(jié)合本試驗(yàn)的實(shí)測(cè)數(shù)據(jù)推導(dǎo)了FRCC構(gòu)件截面(不包括體外預(yù)應(yīng)力筋)塑性鉸長(zhǎng)度與截面受壓區(qū)高度之間的計(jì)算公式Lp=15.1c。采用基于撓度變形的應(yīng)力增量的計(jì)算方法的修正簡(jiǎn)化計(jì)算公式對(duì)試驗(yàn)構(gòu)件進(jìn)行了相應(yīng)的計(jì)算,并與試驗(yàn)結(jié)果進(jìn)行了相應(yīng)的對(duì)比,吻合良好。(5)關(guān)于體外預(yù)應(yīng)力CFRP筋FRCC構(gòu)件的截面開(kāi)裂彎矩的計(jì)算,參考RPC材料的關(guān)于其截面塑性發(fā)展系數(shù)的研究成果,對(duì)試驗(yàn)構(gòu)件進(jìn)行了相應(yīng)的計(jì)算,與試驗(yàn)的結(jié)果相比,表明塑性發(fā)展系數(shù)取為1.65時(shí)具有較好的符合程度。而對(duì)于正常使用階段的體外預(yù)應(yīng)力CFRP筋FRCC構(gòu)件進(jìn)行了剛度分析和最大裂縫寬度的計(jì)算。剛度分析時(shí)考慮了截面受拉區(qū)的拉應(yīng)力的貢獻(xiàn)。進(jìn)行最大裂縫寬度的計(jì)算時(shí),分別根據(jù)基于塑性鉸長(zhǎng)度的原理和基于有粘結(jié)預(yù)應(yīng)力構(gòu)件原理引入體外筋面積的折減系數(shù)來(lái)計(jì)算構(gòu)件的最大裂縫寬度。然后通過(guò)考慮FRCC材料中受拉區(qū)鋼纖維對(duì)截面裂縫開(kāi)展的有利影響,引入鋼纖維所產(chǎn)生的受拉區(qū)影響系數(shù)和峰值壓應(yīng)變的影響系數(shù),提出了體外預(yù)應(yīng)力CFRP筋FRCC梁的最大裂縫寬度的修正計(jì)算公式,對(duì)試驗(yàn)構(gòu)件進(jìn)行了計(jì)算,與試驗(yàn)結(jié)果符合較好。(6)體外預(yù)應(yīng)力CFRP筋]FRCC梁良好的極限變形能力是其相比于體外預(yù)應(yīng)力普通混凝土梁的一個(gè)較為明顯的優(yōu)勢(shì)。由于CFRP筋是一種線性材料,沒(méi)有明顯的屈服點(diǎn),采用傳統(tǒng)的極限位移與屈服位移比值的做法來(lái)分析延性并不完全合適。因此本文根據(jù)Naaman和Jeong提出的采用能量的觀點(diǎn)定義延性指標(biāo)來(lái)揭示其本質(zhì),并通過(guò)加權(quán)平均思想來(lái)確定卸載曲線剛度理論值,然后將基于能量觀點(diǎn)求得的延性指標(biāo)的理論值與試驗(yàn)值進(jìn)行對(duì)比,確定其體外預(yù)應(yīng)力CFRP筋FRCC構(gòu)件的延性水平。(7)本文還采用了有限元軟件Opensees進(jìn)行了建模分析,通過(guò)將試驗(yàn)梁的模擬值與試驗(yàn)值進(jìn)行對(duì)比以驗(yàn)證模型的合理性。然后對(duì)影響構(gòu)件力學(xué)性能的不同參數(shù)做具體分析,主要包括對(duì)構(gòu)件的極限承載力、撓度、體外預(yù)應(yīng)力筋的應(yīng)力增量等力學(xué)指標(biāo)做具體分析,以分析不同參數(shù)下構(gòu)件受力性能的變化趨勢(shì)。綜合試驗(yàn)結(jié)果與理論計(jì)算分析表明：體外預(yù)應(yīng)力CFRP筋FRCC受彎構(gòu)件與體外預(yù)應(yīng)力普通混凝土構(gòu)件相比,在相同配筋率和預(yù)應(yīng)力度下,FRCC構(gòu)件具有較高的極限承載力、優(yōu)異的裂縫分布形態(tài)和較高的延性水平。良好的極限變形能力和較高承載能力為結(jié)構(gòu)向大跨高聳方向發(fā)展提供了可能,而正常使用階段優(yōu)異的裂縫分布發(fā)展對(duì)結(jié)構(gòu)的耐久性、長(zhǎng)周期性能具有較為有利的控制作用。
[Abstract]:Carbon fiber reinforced composite reinforced CFRP (Carbon Fiber Reinforced Polymer) and steel fiber reinforced cement based composites FRCC (Fiber Reinforced Cement Composite) in the field of civil engineering two high-strength building materials. Compared with ordinary reinforced concrete structure, CFRP reinforcement is lightweight, corrosion resistance, fatigue resistance and good physical properties. It can replace the traditional prestressed external tendons as material, it has become a research hotspot. But due to the destruction of the properties of FRP materials and ordinary concrete brittleness, concrete structure with FRP reinforcement ductility is generally poor, and the introduction of appropriate amount of steel fiber FRCC material due to its high strength, ultimate pressure strain and other characteristics, can overcome the inherent defects of the external prestressed CFRP reinforced concrete structure better. And because of the high tensile material Can, can play a larger role in improving crack resistance structure. External prestressed concrete structure using the two kinds of new material combinations, to overcome the corrosion of steel for durability of concrete structure and reduce the weight of structure has important engineering value, provides the possibility for large span structure to the direction of development. This paper mainly uses the the domestic light round CFRP bar and different diameter of fiber reinforced cement base composite materials, the flexural performance of span to depth ratio of external prestressing CFRP tendons 20 cable FRCC flexural members with the corresponding experimental research, including research material properties and mechanical properties. The main research contents include: (1) by using the sandwich type the research group of anchorage independent research and development of two kinds of domestic light round CFRP bar diameter 8mm and 11mm diameter anchorage experimental study on anchorage performance of static load, including CFRP bars The tensile strength, elastic modulus and elongation measurement, obtain the curve of CFRP bars stress-strain relationship. The results show that the CFRP anchor in this assembly can reach the ultimate tensile strength of CFRP bars, no slip phenomenon, has a certain practical value. (2) through the prism and 8 experimental study on the matrix properties of FRCC fiber reinforced cement based composite materials, the main parameters include tensile strength, compressive strength, elastic modulus, ultimate strain and ultimate tensile strain, and obtained the corresponding tensile and compressive properties of the stress-strain curves of the test results, the establishment of the corresponding FRCC uniaxial compression and the constitutive relation of tension (3). Based on the experimental research on the flexural performance of 1 externally prestressed with CFRP tendons concrete beams and 5 prestressed CFRP reinforced FRCC beam has been completed. The experimental parameters include: type of concrete, reinforced with CFRP The diameter and tension control force. According to the test results and the corresponding experimental phenomena analysis of failure modes of structure, stress process, components are discussed in detail the deflection, the stress increment of prestressed tendons. At the same time according to different parameters will test the corresponding component results were compared, analysis of the test results the reason for the difference. The experimental results show that the same ratio of reinforcement and prestressed FRCC beam intensity limit under the condition of bearing capacity are 50% higher than the bearing capacity of reinforced concrete beams, and has better ultimate deformation capacity and ductility level, the ductility level increased by about 35%. In addition, in normal use that stage, the test beam crack distribution and its development path: compared with ordinary concrete beam FRCC beam, the crack distribution shows the characteristics of "small and dense", which is mainly related to the material properties of FRCC, including the Some expansion of steel fiber can restrain the crack bridging, while providing concrete cracking when the stress of the material plastic development more fully, crack distribution. (4) on the basis of experimental research on prestressed CFRP reinforced concrete member force mechanism for the theoretical analysis. Firstly, from the existing calculation method of stress increment of external prestressed tendons reveals the stress mechanism, including the bond discount coefficient method, calculation method of plastic hinge theory based on reinforcement of the comprehensive index method based on Pannel model. Then according to the actual data and the test is derived for the FRCC section (not including in vitro tendons) between the plastic hinge length and depth of compression zone calculation formula of the deflection deformation should be corrected by Lp=15.1c. calculation method of stress increment formula of test structure based on The corresponding calculation, and experimental results are in good agreement with the corresponding contrast. (5) calculation of cracking moment about external prestressing CFRP tendons FRCC components, on the cross-section plastic development coefficient based on research results of RPC materials, the test components were calculated and compared with the test the results show that, consistent with the degree with the plastic development coefficient is 1.65. And the FRCC component of external prestressing CFRP tendons were calculated using normal phase stiffness analysis and maximum crack width. The stiffness analysis considering the sectional tension zone of tensile stress with the maximum crack width was calculated. When respectively according to the principle of plastic hinge length based on a maximum crack width to calculate prestressed component principle introduced in vitro reinforcement area reduction factor. Then by considering the material by FRCC The beneficial effect of steel fiber on the tensile zone of crack section, introduction of the steel fiber produced by the tension effect coefficient of compressive strain coefficient and peak value, put forward the modified calculation formula of maximum crack width of FRCC beams with external CFRP tendons, the test specimens were calculated. Good agreement with the testing results (6) limit]FRCC external CFRP tendons good beam deformation is one of the more obvious advantages compared with the ordinary prestressed concrete beams. The CFRP bar is a kind of linear material, no obvious yield point, using the traditional limit displacement and yield displacement ratio approach to ductility analysis is not entirely appropriate in this paper. According to Naaman and Jeong proposed the definition of ductility index of the point of view of energy to reveal its essence, and through the idea of weighted average to determine the unloading stiffness curve theory value, and then based on energy The view of ductility index the theoretical values were compared with the experimental values, determine its ductility level of external prestressing CFRP tendons FRCC component. (7) this paper uses the finite element software Opensees modeling analysis, were compared to verify the rationality of the model and test the simulation value through the test beam. Then the different parameter values the influence of mechanical properties in detail, including the bearing capacity limit of deflection of the beam, the stress increment of the mechanical index makes a concrete analysis of external prestressed tendons, to analyze the changing trend of the force performance of the component under different parameters. By the comprehensive test results and theoretical analysis show that: FRCC external CFRP tendons bending with prestressed reinforced concrete members should be compared in the same intensity ratio of reinforcement and pre, ultimate bearing capacity of FRCC component is high, morphology and high crack distribution excellent Good ductility level, good limit deformation capacity and high carrying capacity provide the possibility for the structure to develop in a long span and high direction, while the excellent crack distribution in normal operation stage has a favorable control effect on the durability and long term performance of the structure.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TU398.9

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本文編號(hào)：1363966