【摘要】：簡(jiǎn)支T梁隨著預(yù)應(yīng)力鋼筋的張拉,截面承受偏心壓力,梁體自重逐步參與受力,隨著張拉階段的發(fā)展,T梁承受的預(yù)壓應(yīng)力逐漸增大,這時(shí)T梁與張拉臺(tái)座之間將會(huì)慢慢分離,在張拉階段預(yù)應(yīng)力混凝土T梁的受力狀態(tài)較復(fù)雜。張拉階段T梁混凝土養(yǎng)護(hù)時(shí)間限制,其強(qiáng)度未完全達(dá)到其標(biāo)準(zhǔn)抗拉、抗壓強(qiáng)度,在預(yù)應(yīng)力鋼筋的作用下可能會(huì)導(dǎo)致混凝土出現(xiàn)裂縫。預(yù)應(yīng)力鋼筋張拉階段,T梁的受力可以視為簡(jiǎn)支狀態(tài),隨著鋼束張拉數(shù)量的增加,T梁所受的偏心預(yù)壓力逐漸增大,梁體最終產(chǎn)生反拱。分析研究預(yù)應(yīng)力鋼筋張拉階段T梁的應(yīng)力變化以及反拱可以為以后類(lèi)似工程的施工工程提供一定的借鑒。本文以寶貝河大橋的預(yù)應(yīng)力預(yù)制T梁為研究對(duì)象,在主梁預(yù)制階段,預(yù)埋鋼弦式混凝土應(yīng)變計(jì),混凝土強(qiáng)度達(dá)到張拉強(qiáng)度要求時(shí)從T梁兩端同時(shí)進(jìn)行對(duì)稱(chēng)張拉,從而得到張拉階段控制截面的應(yīng)力,利用ANSYS軟件建立T梁的實(shí)體有限元模型,模擬實(shí)際施工過(guò)程中預(yù)應(yīng)力鋼筋張拉產(chǎn)生的預(yù)壓力,將有限元模型計(jì)算的數(shù)據(jù)與實(shí)測(cè)試驗(yàn)數(shù)進(jìn)行對(duì)比以驗(yàn)證模型的準(zhǔn)確性,進(jìn)而對(duì)T梁在張拉階段各控制截面處的應(yīng)力變化及分布規(guī)律進(jìn)行了分析,發(fā)現(xiàn)T梁頂板應(yīng)力在支座附近為拉應(yīng)力,隨著距梁端距離的增大,拉應(yīng)力值逐漸減小,最終過(guò)渡為壓應(yīng)力；分析T梁縱向應(yīng)力沿T梁橫截面的分布規(guī)律,認(rèn)為T(mén)梁梁端存在剪力滯效應(yīng),跨中幾乎不存在該效應(yīng)；為分析不同張拉順序?qū)梁的影響,分別比較了不同張拉順序下T梁的應(yīng)力、反拱、側(cè)向位移的變化,結(jié)果表明不同張拉過(guò)程對(duì)T梁截面的應(yīng)力變化及側(cè)彎影響較大,但對(duì)最終反拱值影響不大；根據(jù)對(duì)錨固端的模擬,研究了局部承壓混凝土的應(yīng)力分布規(guī)律,結(jié)果表明錨下混凝土存在應(yīng)力集中現(xiàn)象,此現(xiàn)象隨著距錨固端距離的增大而逐漸消失,應(yīng)力最終均勻的作用于截面上。
[Abstract]:With the tensioning of prestressed steel bar, the section of simply supported T beam is subjected to eccentric pressure, the weight of beam body gradually takes part in the force, and with the development of tensioning stage, the preloading stress of T beam increases gradually, and then the T-beam and the tensioning pedestal will be separated slowly. The stress state of prestressed concrete T-beam is more complicated in the tensioning stage. The strength of T-beam concrete in tensioning stage is not up to the standard tensile strength and compressive strength, which may lead to concrete cracks under the action of prestressed steel bar. The stress of T-beam in the tensioning stage of prestressed steel bar can be regarded as a simply supported state. With the increase of the number of steel strands, the eccentric preloading of T-beam increases gradually, and the beam body finally produces a reverse arch. The analysis and study of the stress change of T-beam in the tensioning stage of prestressed steel bar and the reverse arch can provide some reference for the construction of similar projects in the future. In this paper, prestressing prefabricated T-beam of Baohe Bridge is taken as the research object. In the prefabrication stage of the main beam, the steel string strain gauge is prefabricated, and the concrete strength reaches the tensile strength requirement, when the concrete strength reaches the requirement of tensile strength, the symmetrical tension is carried out simultaneously from the two ends of the T beam. The stress of the controlled section in tension stage is obtained, and the finite element model of T-beam is established by ANSYS software, and the pre-pressure produced by the tensioning of prestressed steel bar in actual construction is simulated. The data calculated by the finite element model are compared with the measured experimental data to verify the accuracy of the model, and the stress variation and distribution law of each control section of the T-beam in the tension stage are analyzed. It is found that the roof stress of T-beam is tensile stress near the support, and with the increase of the distance from the end of the beam, the value of tensile stress decreases gradually, and the ultimate transition is compressive stress, and the distribution of longitudinal stress of T-beam along the cross-section of T-beam is analyzed. It is considered that there is shear lag effect at the end of T-beam and almost no effect in the middle of span. In order to analyze the influence of different tensioning order on T-beam, the stress, reverse arch and lateral displacement of T-beam under different tensioning order are compared respectively. The results show that different tensioning processes have great influence on the stress change and lateral bending of T-beam section, but have little effect on the ultimate reverse arch value, according to the simulation of anchoring end, the stress distribution law of local confined concrete is studied. The results show that there is a stress concentration phenomenon in the concrete under anchor, which disappears gradually with the increase of the distance from the anchoring end, and the stress finally acts uniformly on the section.
【學(xué)位授予單位】：東北林業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：U445.57

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本文編號(hào)：2119541