本文選題：體外預(yù)應(yīng)力 + 鋼絲繩��； 參考：《東北林業(yè)大學(xué)》2014年博士論文

【摘要】：隨著我國(guó)經(jīng)濟(jì)和社會(huì)的快速發(fā)展,大量舊有橋梁的維修加固問題日益突出,在諸多橋梁加固方法中,體外預(yù)應(yīng)力加固技術(shù)以其中斷交通時(shí)間短、施工簡(jiǎn)便、經(jīng)濟(jì)高效、加固效果好等有點(diǎn),被廣泛用于舊橋加固施工中。而在既有橋梁中,梁端受剪破壞是一種常見的破壞形式,主要表現(xiàn)為主拉應(yīng)力裂縫數(shù)量多,寬度超限,斜裂縫向跨中發(fā)展,嚴(yán)重影響結(jié)構(gòu)的安全。造成受剪破壞的原因主要有抗剪承載力不足、材料性能退化、車輛超載等。目前,對(duì)抗剪能力加固,主要有粘貼鋼板、粘貼高強(qiáng)復(fù)合材料、增大截面、體外預(yù)應(yīng)力等加固方法。其中前三種均屬于被動(dòng)加固,只有體外預(yù)應(yīng)力法屬于主動(dòng)加固,經(jīng)常與抗彎加固配合作用,效果良好,但需設(shè)置轉(zhuǎn)向塊,構(gòu)造復(fù)雜,施工繁瑣。鋼絲繩體外預(yù)應(yīng)力加固,采用分散的鋼絲繩進(jìn)行加固,預(yù)應(yīng)力分散布置,噸位小,錨固簡(jiǎn)便,不需轉(zhuǎn)向裝置,施工方便,是抗剪加固的一種新的嘗試,為舊有混凝土橋梁及部分大跨徑預(yù)應(yīng)力混凝土橋梁普遍存在的斜裂縫加固提供新的途徑,以改善橋梁受力狀況、保證橋梁運(yùn)營(yíng)安全、延長(zhǎng)橋梁的使用壽命,帶來明顯的直接及間接經(jīng)濟(jì)效益。本文的主要內(nèi)容和研究結(jié)果如下： (1)體外預(yù)應(yīng)力筋加固效果的研究 模擬舊橋使用損傷狀態(tài),設(shè)計(jì)3片基準(zhǔn)梁和23片加固梁進(jìn)行體外預(yù)應(yīng)力鋼絲繩加固試驗(yàn),試驗(yàn)梁截面尺寸為20cm×40cm,梁長(zhǎng)為300cm,對(duì)加固梁的抗剪效果進(jìn)行了系統(tǒng)的試驗(yàn)研究,試驗(yàn)內(nèi)容包括體外筋加固作用對(duì)加固梁的極限承載力、裂縫變化、箍筋應(yīng)變的影響,試驗(yàn)結(jié)果表明,體外預(yù)應(yīng)力筋加固方法能夠有效提高鋼筋混凝土梁的抗剪能力,推遲梁體開裂,提高箍筋屈服荷載。 (2)試驗(yàn)梁設(shè)計(jì)參數(shù)對(duì)加固效果的影響 按照試驗(yàn)梁的設(shè)計(jì)參數(shù)建立非線性有限元計(jì)算模型,對(duì)設(shè)計(jì)模型進(jìn)行抗剪承載力計(jì)算,并加密設(shè)計(jì)參數(shù)彌補(bǔ)試驗(yàn)梁的不足,通過非線性有限元方法對(duì)待加固梁的混凝土強(qiáng)度等級(jí)、體內(nèi)配箍率、縱向配筋率等設(shè)計(jì)參數(shù)以及體外參數(shù)包括鋼絲繩間距、預(yù)加力大小、加固梁帶載水平等因素對(duì)抗剪加固效果的影響進(jìn)行了理論研究,揭示了體外鋼絲繩抗剪加固的機(jī)理,總結(jié)了原梁參數(shù)和體外參數(shù)對(duì)加固效果的影響規(guī)律。計(jì)算結(jié)果表明,有限元計(jì)算結(jié)果與試驗(yàn)結(jié)果吻合良好；抗剪承載力隨著配箍率、縱筋配筋率、混凝土標(biāo)號(hào)、體外筋預(yù)加力的增大而明顯提高,隨著剪跨比、帶載水平、體外筋間距的增大而減小 (3)加固梁抗剪承載能力計(jì)算方法的研究 綜合分析了國(guó)內(nèi)外現(xiàn)有的抗剪承載力計(jì)算方法,在此基礎(chǔ)上采用遺傳-回歸的方法,利用Matlab計(jì)算軟件對(duì)試驗(yàn)數(shù)據(jù)和有限元計(jì)算數(shù)據(jù)進(jìn)行優(yōu)化分析,建立了基于桁架-拱模型的抗剪承載力計(jì)算模型,提出了體外鋼絲繩、帶載水平和混凝土損傷三個(gè)系數(shù)η1、η2、η3。并根據(jù)本課題抗剪加固試驗(yàn)數(shù)據(jù)檢驗(yàn)了所提公式的可靠性。 本文的研究成果為體外預(yù)應(yīng)力加固鋼筋混凝土梁的加固設(shè)計(jì)、施工方案、承載力計(jì)算提供了理論依據(jù),可供參考使用。
[Abstract]:With the rapid development of our country's economy and society, the problem of maintenance and reinforcement of a large number of old bridges is becoming more and more prominent. In the reinforcement methods of many bridges, the technology of external prestressing reinforcement is a bit short of traffic time, simple construction, economical efficiency and good reinforcement effect. It is widely used in the old bridge reinforcement construction. In the existing bridge, Liang Duan Shear failure is a common form of failure, mainly manifested as the number of tensile stress cracks, the width of the limit, the slanting cracks developing to the midspan, which seriously affects the safety of the structure. The main reasons for the shear failure are the lack of shear capacity, the degradation of material properties, the overload of vehicles, etc. The strengthening methods such as high strength composite material, enlarging cross section and external prestressing force are added. The first three kinds are passive reinforcement, only the external prestressing method belongs to the active reinforcement, and the effect is good, but the steering block is set up, the structure is complicated and the construction is complicated. The steel wire rope is strengthened by external prestressing force, and the dispersed wire rope is used. It is a new attempt to reinforce the shear strength of the old concrete bridges and some large span prestressed concrete bridges. It provides a new way for the reinforcement of the old concrete bridges and some large span prestressed concrete bridges, in order to improve the stress condition of the bridge, ensure the safety of the bridge operation, and prolong the bridge operation. The service life of bridges brings obvious direct and indirect economic benefits. The main contents and results of this paper are as follows:
(1) study on the reinforcement effect of external prestressing tendons
To simulate the damage state of the old bridge, 3 datum beams and 23 reinforced beams are designed to reinforce the external prestressed steel wire rope. The test beam section size is 20cm x 40cm and the beam length is 300cm. The shear effect of the reinforced beam is systematically tested. The test contents include the ultimate bearing capacity of the reinforcement beam and the crack change. The experimental results show that the reinforcement method can effectively improve the shear ability of the reinforced concrete beams, postpone the cracking of the beam and increase the yield load of the stirrup.
(2) the influence of the design parameters of the test beam on the reinforcement effect
According to the design parameters of the test beam, the nonlinear finite element calculation model is established. The shear bearing capacity of the design model is calculated, and the design parameters are encrypted to make up the shortage of the test beam. The concrete strength grade of the reinforced beam is treated by the nonlinear finite element method, the design parameters such as the stirrup rate in the body, the longitudinal reinforcement ratio, and the parameters including the steel in vitro include steel. The effect of wire rope distance, preloading size, reinforcing beam carrying level and other factors on the effect of shear reinforcement is theoretically studied. The mechanism of shear reinforcement of steel wire rope in vitro is revealed, and the influence laws of the parameters of the original beam and the external parameters on the reinforcement effect are summarized. The calculation results show that the results of finite element calculation are in good agreement with the test results; The shear bearing capacity increases with the ratio of stirrup, the reinforcement ratio of the longitudinal reinforcement, the concrete mark and the preloading of the external tendons. With the shear span ratio, the load level and the increase of the distance between the external tendons, the shear strength decreases.
(3) calculation method for shear bearing capacity of reinforced beams
The calculation method of shear bearing capacity at home and abroad is synthetically analyzed. On this basis, the method of genetic regression is adopted, and the Matlab software is used to optimize the test data and the finite element calculation data. The calculation model of the shear bearing capacity based on the truss arch model is established, and the steel rope in vitro, the carrying level and the concrete are put forward. Three damage coefficients 1, 2 and 3. are tested, and the reliability of the formula is verified according to the test data.
The research results in this paper provide a theoretical basis for reinforcement design, construction plan and bearing capacity calculation of external prestressed reinforced concrete beams, which can be used for reference.
【學(xué)位授予單位】：東北林業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：U445.72;U441

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