Time-dependent reinforced concrete slab deflections
TL;DR: In this article, a finite element analysis to determine time-dependent deflections of reinforced concrete slabs, including the effects of cracking, creep, and shrinkage, is presented, which employs a 16-degree-of-freedom layered rectangular plate bending element, and uses a numerical time integration scheme to evaluate creep/shrinkage strains determined from CEB parameters.
Abstract: A finite element analysis to determine time-dependent deflections of reinforced concrete slabs, including the effects of cracking, creep, and shrinkage, is presented. The analysis employs a 16-degree-of-freedom layered rectangular plate bending element, and uses a numerical time integration scheme to evaluate creep and shrinkage strains determined from CEB parameters. The initial strain technique is used in the solution procedure. Predicted results are compared with the limited experimental results in the literature.
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TL;DR: In this paper, a line search method was proposed to improve the convergence of the arc-length solution for both geometrically nonlinear analysis of shallow shells and material nonlinear analyses of reinforced concrete beams and slabs.
Abstract: This paper describes a method for introducing line searches into the arc-length solution procedure. Such line searches may be used at each iteration to calculate an optimum scalar step-length which scales the normal iterative vector. In practice, a loose tolerance is provided so that on many iterations the line searches are avoided. However on ‘difficult iterations’, the line searches are shown to lead to a substantial improvement in the convergence characteristics. A simple single-parameter acceleration is also developed using line search concepts. The new arc-length method is applied to both the geometrically nonlinear analysis of shallow shells and the materially nonlinear analysis of reinforced concrete beams and slabs. Significant improvements are demonstrated in relation to the standard arc-length method.
466 citations
TL;DR: In this article, the major sources of nonlinearities in reinforced concrete structures are discussed and a large number of proposed mathematical models for the material behaviour of concrete and reinforcement and for the interactive behaviour between the two materials.
164 citations
TL;DR: In this paper, the authors developed an inverse approach combining nonlinear numerical analysis and global experimental response to develop the tension stiffening model parameters needed to simulate homogenized concrete behavior in tension.
Abstract: Cracking is an important aspect of concrete behavior that considerably affects the overall response of concrete structures The initiation of cracks is governed by concrete tensile properties The propagation of cracks is a complicated phenomenon that plays a significant role in the nonlinear analysis of concrete structures The cracking process in tension starts at a relatively low tensile strain, causing plain concrete to exhibit a gradual softening behavior This softening is augmented by the tension stiffening of reinforcing bars The smeared crack approach is typically combined with nonlinear finite-element analysis to generate an accurate global response The key to such representative accurate predictions relates to material parameters, especially those of tension stiffening effects For a complete understanding of the crack development process, tests should be performed on concrete specimens at various load histories However, due to the difficulty of testing concrete in uniaxial tension, only limited and often conflicting results are available The present work develops an inverse approach combining nonlinear numerical analysis and global experimental response to develop the tension stiffening model parameters needed to simulate homogenized concrete behavior in tension The results of the study provide good model parameters to use in the case of concrete beams reinforced with steel and fiber-reinforced polymer (FRP) bars
149 citations
TL;DR: In this paper, a 3D finite element (FE) model for the accurate prediction of both the thermal and the mechanical behavior of reinforced concrete (RC) beams exposed to fire is presented.
123 citations
Cites background from "Time-dependent reinforced concrete ..."
...Scanlon and Murray [72] proposed the use of an average stress-strain relationship for the tensile concrete in the descending branch....
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01 Jan 1989
TL;DR: In this article, the concept involving Mode I type cracking is broadened to include mixed mode fracture interpretation of the shear retention factor, if the crack memory is fully retained, and the degradation of strength due to tensile cracking and decohesion in shear in terms of isotropic and anisotropic strain softening concepts.
Abstract: For numerical simulation of fracture in concrete and rock the “smeared crack approach” is receiving increasing attention. On one hand renewed attempts in terms of the fixed and rotating crack models resort to fracture mechanics in order to refine the traditional orthotropic crack formulation. Along this approach the original concept involving Mode I type cracking is being broadened to include mixed mode fracture interpretation of the shear retention factor, if the crack memory is fully retained. On the other hand, fracture energy-based plasticity models are advocated by the authors, as well as other investigators, which describe the degradation of strength due to tensile cracking and decohesion in shear in terms of isotropic and anisotropic strain-softening concepts.
119 citations