Author: Pui-Lam Ng

Publisher: Open Dissertation Press

Published: 2017-01-27

Total Pages:

ISBN-13: 9781361429587

This dissertation, "Constitutive Modelling and Finite Element Analysis of Reinforced Concrete Structures" by Pui-lam, Ng, 吳沛林, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled CONSTITUTIVE MODELLING AND FINITE ELEMENT ANALYSIS OF REINFORCED CONCRETE STRUCTURES Submitted by NG Pui Lam for the Degree of Doctor of Philosophy at The University of Hong Kong in September 2007 This thesis is divided into two parts. The first part is devoted to the development of new constitutive models of reinforced concrete. To properly simulate the stress path dependence of concrete, the author devises herein the nonlinear damage model. In this model, the microcracking induced by stressing of concrete is viewed as damage, which is described by two quantifiable damage parameters: the damaged modulus and the residual strain. On the shear behaviour of concrete, it is postulated that the shear stress envelope of concrete is governed by two criteria: the Mohr-Coulomb criterion of maximum shear stress and the non- orthogonal minor crack criterion of maximum shear stress. A stress path dependent shear stress-strain relation of concrete is established. Time dependent analysis of shrinkage and creep effects in concrete structures requires storage of stress histories of finite elements for evaluation of creep. This poses a hindrance to the analysis of large problems. To circumvent the memorisation of stress histories, a new multi-layer visco-elastic concrete creep model is developed. Besides, for structures constructed in stages, re-analysis of the partially completed structure in each stage is necessary in response to changes in structural configurations during construction. Herein, the locked-in strain is introduced to allow analysing altogether the completed and uncompleted portions, thus eliminating the efforts on re-meshing and location matching of element stresses and deformations. The interactions between concrete and reinforcement are simulated in conjunction with the discrete modelling of reinforcing bars. The Goodman interface element is adapted for modelling concrete-to-reinforcement bond with the implementation of nonlinear bond stress-slip relation. Besides, the dowel action for discrete reinforcing bars is modelled based on the beam on elastic foundation theory. The second part of this thesis is on the analysis of reinforced concrete structures. The tension stiffening phenomenon in cracked concrete beams is investigated. From finite element analysis, stress distributions at beam cross-sections are revealed and based on which a tensile stress block is derived. The tensile stress block enables assessment of beam deflections in structural design process without resorting to finite element analysis for each individual beam. Furthermore, the post- peak behaviour of beams and deep beams is analysed. The effects of concrete residual strain, bond slip, and dowel action on beam responses are studied. The finite element programme is applied to the analysis of shear transfer across joints between concrete units, with particular reference to precast segmental post-tensioned bridges. To model the epoxy adhesive between joint surfaces, the epoxy element is developed from the nonlinear linkage element. It is found that with the joint surfaces pressing against each other by prestressing, the shear transfer capacity of flat joints is already sufficient (comparable to intact concrete), and the provision of shear keys at joint surfaces is superfluous from the shear stren