双向板裂缝及长期开裂挠度的有限元非线性分析

简述了受压混凝土的徐变基本理论和裂缝间受拉混凝土对开裂构件刚度硬化的分析模型,并解读了GB50010-2010,ACI 318-08的EC 2∶2004有关裂缝和挠度计算条文的理论背景.其中,EC 2∶2004使用徐变系数φ(t,t0)、混凝土龄期调整弹性模量(E)c(t,t0)和刚度插入系数ζ,三个反映徐变和开裂刚度...

FEM non-linear analysis of cracks and long-term crack deflection of two-way slab

The basic theory of compressive concrete creep and the analysis model of the stiffness and hardening of cracked components caused by the tension between cracks were briefly described, and the theoretical backgrounds of the crack and deflection calculation provisions of GB 50010—2010, ACI 318-08 and EC 2∶2004 were interpreted. Among them, the EC 2∶2004 provides three design parameters reflecting creep and cracking stiffness to calculate the semi-empirical formula of crack width and long-term deflection, including creep coefficient φ(t,t0), age-adjusted elasticity modulus Ec(t,t0) and stiffness interpolation coefficient ζ, and they are generally suitable to both beam and two-way slab. On the other hand, the direction of principal stresses changes in the two-way slab. With the plate-bending elements embedded φ(t,t0),Ec(t,t0) and ζ, FEM non-linear analysis is a general method of crack and long-term crack deflection of two-way slab. After listing the basic process of finite element non-linear analysis, as a calculation example, CSI.SAFE was used to complete the cross-section design of the basement column-supported bidirectional top slab and the calculation of the cracks in the service limit state and the long-term deflection, also the calculation method was compared with the slab-strip method. The method was compared. The applicability and limitations of the GB 50010—2010 and EC 2∶2004 for the calculation of cracks and deflection were verified, and opinions on the calculation methods of cracks and long-term deflection of two-way slabs were given.