约束混凝土柱高强箍筋和混凝土局压区高强间接钢筋合理配置研究

The wide-ranging application of high-yield-strength steel is a national policy. Confined concrete columns include spiral stirrup confined concrete and wet format stirrup confined concrete. For a long time, it is believed that stirrups must reach their yield strength when the confined concrete columns damage in designing and calculating. In fact, no matter how high the stirrup yield strength is, the volumetric ratio must be limited in a certain region if the stirrups yield when confined concrete reach the failure load. This project is to obtain the relationship between confined concrete compressive peak stress, volumetric ratio and yield strain based on test data. Combined with modified traditional confined concrete compressive strength formulas, maximum volumetric rations formulas of different intensity of stirrups are proposed, and then apply them to designing and calculating of bearing capacity of concrete reinforced by orthogonal ties. Then, this project establishes different constraints concrete compressive stress - strain relationship model based on high, medium and low level of constraint which could consider reasonably the relatively small later deformation of high strength concrete and relatively large lateral deformation when stirrup reach yield strength. It will provide reference for the reasonable design of confined concrete column and edge component of shear wall.

在混凝土结构中推广高强钢筋是国策。约束混凝土柱包括配置螺旋式箍筋约束混凝土柱和网格式箍筋约束混凝土柱。长期以来，人们在进行约束混凝土柱设计计算时认为当达到破坏荷载时箍筋抗拉强度一定能充分发挥。事实上，不论箍筋屈服强度高低，约束混凝土柱达到破坏荷载时箍筋抗拉强度要得到充分发挥，箍筋的体积配箍率都必须限定在一定的区间。本项目将基于试验结果，建立约束混凝土峰值压应力与体积配箍率和箍筋屈服应变的关系式，将该式与改进的传统约束混凝土抗压强度计算公式联立，建立不同强度等级约束箍筋最大体积配箍率计算公式，并将不同强度等级约束箍筋体积配箍率的适用区间发展到混凝土局压承载力设计计算。建立合理考虑高强混凝土受压横向变形相对偏小，高强约束箍筋受拉屈服时要求约束混凝土横向变形相对偏大等特点的适用高、中、低约束程度的约束混凝土受压应力—应变关系模型。为约束混凝土柱及剪力墙的约束混凝土边缘构件的合理设计提供依据。

在一定的体积配箍率范围内，当箍筋约束混凝土达到抗压强度时，箍筋可能未达到屈服。此时，采用箍筋屈服强度计算的约束混凝土抗压强度是偏于不安全的。因此，开展约束混凝土柱高强箍筋和混凝土局压区高强间接钢筋合理配置研究，具有重要的理论意义和实用价值。.完成了188根螺旋式箍筋约束混凝土圆柱和173根网格式箍筋约束混凝土方柱的轴心受压试验，提出了约束混凝土达到抗压强度时箍筋能够屈服的体积配箍率下限值和低于该下限值时的箍筋拉应变计算公式。基于本项目得到的箍筋约束混凝土轴心受压试验结果及相关文献的试验数据，建立了具有较高普适性的约束混凝土受压应力-应变关系模型。提出了箍筋约束混凝土峰值压应力和峰值压应变等计算公式。完成了15根箍筋约束混凝土方柱的拟静力试验，揭示了轴压比、剪跨比、纵筋配筋率及体积配箍率等关键参数对作箍筋约束混凝土柱抗震性能的影响。完成了28个配置螺旋式间接钢筋的混凝土局压试件和28个配置网格式间接钢筋的混凝土试件的局压试验，考察了达到局压破坏荷载时间接钢筋拉应力水平的发展规律。提出了间接钢筋能够受拉屈服的体积配筋率下限值和低于体积配筋率下限值时间接钢筋拉应力计算方法。.本项目的研究成果为箍筋约束混凝土柱的合理设计提供了依据，为局压设计时合理布置间接钢筋并合理考虑间接钢筋应力水平提供了依据。此外，相关研究成果为《多螺旋箍筋柱应用技术规程》（T/CECS 512-2018）的编制提供了部分依据。