Influence of Tension Stiffening and Cracked Shear Modulus Models on Non-Linear Analysis of High Strength Fibrous Reinforce

Abstract

In the present study, new models are suggested and proposed for cracked shear modulus and tension stiffening to study their effect on the response of the slab. These models are used in the nonlinear analysis of High Strength Steel Fiber Reinforced Concrete (HSSFRC) slabs. The suggested models have multiple shapes depending on the curvature factor, these models are compared with the well-known formulas used in previous studies and great agreements are achieved. The Serendipity “eight-node” element type has been adopted for representing the concrete and layered approach is used to simulate the concrete elements and a smeared layer approach is used to represent the steel reinforcement. The concrete compression behavior is modeled using strain hardening plasticity method, the first two stress invariants of the yield condition is used. For finite element analysis, a computer program coded in Fortran 90 is developed and used for performing nonlinear analysis on the slab. In order to check the validity of the current models, many actual results for testing slabs “in the laboratory” are compared with the results from the present study and a great agreement is achieved. All studied slabs were simply supported from four sides and loaded with concentrated load at the middle of the slab, but slab S5 is simply supported by two opposite parallel sides with line load parallel to the supports at the middle of the span of the slab. For the curvature factors (B_t, B_g) it is found that the values (B_t =0.005-0.5, B_g =0.001-0.05) give the best simulation for the slab. The effect of tension stiffening model is more than the effect of cracked shear modulus model and there is an interaction between tension stiffening and cracked shear modulus models.