配置高强竖向预应力筋混凝土梁抗剪性能试验研究

发布时间：2018-04-30 02:17

本文选题：混凝土梁 + 抗剪性能　；参考：《土木工程学报》2014年05期

【摘要】：目前国内外有代表性的混凝土结构设计规范对配置三向预应力混凝土箱梁的抗剪设计均未考虑竖向预应力对梁抗剪承载能力的影响,并对梁内抗剪钢筋的抗拉设计强度取值进行了限制,是否合适值得重新审视。对4片配置高强竖向预应力筋混凝土工字梁的抗剪性能进行了试验研究,主要研究纵向和竖向预应力的施加对配置高强竖向预应力筋混凝土梁抗剪性能的影响以及试验梁剪切破坏时高强竖向预应力筋的强度发挥水平。结果表明:就所研究的情形而言,施加3.2MPa竖向预压应力可使梁斜截面开裂荷载提高约22%、临界斜裂缝倾角增加约17°、抗剪承载能力提高约30%。剪切破坏时,竖向预应力筋是否张拉对加载过程中抗剪钢筋的应变增量影响很小,未张拉的竖向抗剪钢筋内最大应力为713MPa,预张拉后,抗剪钢筋最大应力增量为709MPa,但叠加其初始张拉应力后其内最大应力可达1440MPa。对竖向抗剪钢筋进行张拉能使高强抗剪钢筋的强度得到较好发挥,但同时导致临界斜裂缝的倾角增大、水平投影长度减小。因此,与配置普通箍筋的混凝土梁抗剪设计相比,配置竖向高强预应力筋混凝土梁竖向抗剪钢筋的最小间距、最小配筋率及初始张拉应力均应特别考虑。
[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.

【作者单位】：湖南大学;
【基金】：国家自然科学基金(51078134)
【分类号】：TU378.2;TU317

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