本文選題：混凝土梁 + 抗剪性能　； 參考：《土木工程學(xué)報》2014年05期

【摘要】：目前國內(nèi)外有代表性的混凝土結(jié)構(gòu)設(shè)計規(guī)范對配置三向預(yù)應(yīng)力混凝土箱梁的抗剪設(shè)計均未考慮豎向預(yù)應(yīng)力對梁抗剪承載能力的影響,并對梁內(nèi)抗剪鋼筋的抗拉設(shè)計強度取值進行了限制,是否合適值得重新審視。對4片配置高強豎向預(yù)應(yīng)力筋混凝土工字梁的抗剪性能進行了試驗研究,主要研究縱向和豎向預(yù)應(yīng)力的施加對配置高強豎向預(yù)應(yīng)力筋混凝土梁抗剪性能的影響以及試驗梁剪切破壞時高強豎向預(yù)應(yīng)力筋的強度發(fā)揮水平。結(jié)果表明:就所研究的情形而言,施加3.2MPa豎向預(yù)壓應(yīng)力可使梁斜截面開裂荷載提高約22%、臨界斜裂縫傾角增加約17°、抗剪承載能力提高約30%。剪切破壞時,豎向預(yù)應(yīng)力筋是否張拉對加載過程中抗剪鋼筋的應(yīng)變增量影響很小,未張拉的豎向抗剪鋼筋內(nèi)最大應(yīng)力為713MPa,預(yù)張拉后,抗剪鋼筋最大應(yīng)力增量為709MPa,但疊加其初始張拉應(yīng)力后其內(nèi)最大應(yīng)力可達1440MPa。對豎向抗剪鋼筋進行張拉能使高強抗剪鋼筋的強度得到較好發(fā)揮,但同時導(dǎo)致臨界斜裂縫的傾角增大、水平投影長度減小。因此,與配置普通箍筋的混凝土梁抗剪設(shè)計相比,配置豎向高強預(yù)應(yīng)力筋混凝土梁豎向抗剪鋼筋的最小間距、最小配筋率及初始張拉應(yīng)力均應(yīng)特別考慮。
[Abstract]:At present, the typical design specifications of concrete structure at home and abroad have not considered the effect of vertical prestress on shear bearing capacity of the beam in three direction prestressed concrete box girder, and limit the design strength of the tensile strength of the shear bar in the beam. It is worth reexamining whether it is suitable for 4 pieces of high strength vertical precondition. The shear performance of the stress reinforced concrete beam is studied. The effect of the longitudinal and vertical prestress on the shear performance of the concrete beams with high strength vertical tendons and the strength of the high strength vertical tendons in the shear failure of the test beams are studied. The results show that, as far as the study is concerned, 3 The vertical preloading stress of.2MPa can increase the cracking load of the inclined section of the beam by about 22%, the critical inclined crack inclination increase by about 17 degrees, and the shear bearing capacity increases about 30%. shear failure. The tensile strength of the vertical prestressing tendons has little effect on the strain increment of the shear bar in the loading process, and the maximum stress in the vertical shear bar is 713MPa, pretensioning. After pulling, the maximum stress increment of the shear bar is 709MPa, but the maximum stress in the tensile stress can reach 1440MPa. after the initial tensile stress is superimposed, and the tensile energy of the vertical shear reinforcement can make the strength of the high-strength shear bar better, but at the same time, the angle of the critical inclined crack increases and the length of the horizontal projection is reduced. Therefore, the common stirrup is arranged with the common stirrup. Compared with the shear design of concrete beams, the minimum spacing, the minimum reinforcement ratio and the initial tensile stress of the vertical shear reinforcement of the concrete beams with vertical high strength prestressed reinforcement should be considered.

【作者單位】： 湖南大學(xué);
【基金】：國家自然科學(xué)基金(51078134)
【分類號】：TU378.2;TU317

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本文編號：1822628