Non Linear Finite Element Model For Partially Prestressed Concrete Structures Under Cyclic Loads

This book details the theory and applications of finite element (FE) modeling of post-tensioned (PT) concrete structures, and provides the updated MATLAB code (as of 2019). The challenge of modeling PT prestressed concrete structures lies in the treatment of the interface between the concrete and prestressing tendons. Using MATLAB, this study develops an innovative nonlinear FE formulation which incorporates contact techniques and engineering elements to considerably reduce the need of computational power. This FE formulation has the ability to simulate different PT frame systems with fully bonded, fully unbonded or partially bonded tendons, as well as actual sliding behavior and frictional effects in the tendons. It also allows for the accurate simulation of anchor seating loss.

Experimental programs in laboratories give real results to identify nonlinear behavior of reinforced concrete (RC) structures but they are limited to knowledge of particular cases under restricted structural dimensions, sizes, shapes, loading and boundary conditions but the computational simulation approach has no limit to its application. Constitutive models are developed to simulate the dynamic nonlinear response of concrete and steel reinforcement subjected to cyclic loading varying randomly in magnitude. The behavior of structural concrete under monotonic loading is affected by important material aspects including cracking, crushing, tension stiffening, compression softening and bond slip. Reversed cyclic loading introduces further complexities such as stiffness degradation in concrete and the Bauschinger effect in reinforcing steel. In this research the validity and reliability of some proposed constitutive models for concrete considering general loading i.e. cyclic, monotonic, partial, common point and transition loading are evaluated. Amongst many existing constitutive models, because of their simplicity and common usage in the finite element analysis of RC structures, only some common proposed models based on nonlinear elasticity-based approach are investigated. These models are verified against experimental data available in the literature and the results are discussed. In this study, also, a hysteretic stress–strain model is developed for unconfined concrete with the intention of providing efficient modeling for the structural behavior of concrete in seismic regions. The proposed model is based on the findings of previous experimental and analytical studies. The model for concrete subjected to monotonic and cyclic loading, comprises four components in compression and tension; an envelope curve (for monotonic and cyclic loading), an unloading curve, a reloading curve, and transition curve. Also presented are formulations for partial unloading and partial reloading curves. The proposed Constitutive model reliability is investigated by RC members non-linear finite element analysis (FEM) using by finite element software ABAQUS. Comparisons with test results showed that the proposed model provides a good fit to a wide range of experimentally established hysteresis loops.

This text provides a review of relevant knowledge in the area of constitutive modelling of concrete steel bonds and their interaction. It discusses the problems encountered in assembling the various elements with the purpose of constructing the model of an element made of reinforced concrete. Whether physically or empirically based, very simple or sophisticated, long-established or brand new, the models presented in this book are produced in as rational a framework as possible, and are accompanied by comments on their advantages and limitations.

Unified Theory of Concrete Structures develops an integrated theory that encompasses the various stress states experienced by both RC & PC structures under the various loading conditions of bending, axial load, shear and torsion. Upon synthesis, the new rational theories replace the many empirical formulas currently in use for shear, torsion and membrane stress. The unified theory is divided into six model components: a) the struts-and-ties model, b) the equilibrium (plasticity) truss model, c) the Bernoulli compatibility truss model, d) the Mohr compatibility truss model, e) the softened truss model, and f) the softened membrane model. Hsu presents the six models as rational tools for the solution of the four basic types of stress, focusing on the significance of their intrinsic consistencies and their inter-relationships. Because of its inherent rationality, this unified theory of reinforced concrete can serve as the basis for the formulation of a universal and international design code. Includes an appendix and accompanying website hosting the authors’ finite element program SCS along with instructions and examples Offers comprehensive coverage of content ranging from fundamentals of flexure, shear and torsion all the way to non-linear finite element analysis and design of wall-type structures under earthquake loading. Authored by world-leading experts on torsion and shear

These volumes contain the edited documents presented at the NATO-Sponsored Advanced Research Workshop (ARW) on Partial Pre8tre88ing, from Theory to Practice, held at the CEBTP Research Centre of Saint-Remy-Ies-Chevreuse, France, June 18-22, 1984. The workshop was a direct extension of the International Symposium on Nonlinearity and Continuity in Pre8tre88ed Concrete, organized by the editor at the University of Waterloo, Waterloo, Canada, July 4-6, 1983. The organization of the NATO-ARW on Partial Prestressing was prompted by the need to explain and reduce the wide dirrerences of expert oph:iipn· on the subject, which make more difficult the accep tance of partial prestressing by the profession at large. Specifically, the workshop attempted to: - produce a more unified picture of partial presetressing, by con fronting and, where possible, reconciling some conflicting American and European views on this subject; - bring theoretical advances on partial prestressing within the grasp of engineering practice; - provide the required background for developing some guidelines on the use of partial prestressing, in agreement with existing structural concrete standards. The five themes selected for the workshop agenda were: (1) Problems of Partially Prestressed Concrete (PPC). (2) Partially Prestressed Concrete Members: Static Loading. (3) PPC Members: Repeated and Dynamic Loadings. (4) Continuity in Partially Prestressed Concrete. (5) Practice of Partial Prestressing.

Dynamics of Civil Structures, Volume 2. Proceedings of the 34th IMAC, A Conference and Exposition on Dynamics of Multiphysical Systems: From Active Materials to Vibroacoustics, 2016, the second volume of ten from the Conference brings together contributions to this important area of research and engineering. Th e collection presents early fi ndings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: • Modal Parameter Identifi cation • Dynamic Testing of Civil Structures • Human Induced Vibrations of Civil Structures • Model Updating • Operational Modal Analysis • Damage Detection • Bridge Dynamics • Experimental Techniques for Civil Structures • Hybrid testing • Vibration Control of Civil Structures