Methodology for the analysis of post-tensioned structures using a constitutive serial-parallel rule of mixtures

Abstract

The main purpose of this paper is to develop a reliable method based on a three-dimensional (3D) finiteelement (FE) model to simulate the constitutive behaviour of reinforced concrete structures strengthened with post-tensioned tendons taking into account the reduction of the pre-stressing stress due to the steel relaxation. The pre-tensioned concrete is modelled as a composite material whose behaviour is described with the serial-parallel rule of mixtures (S/P RoM) [1-3] whereas the stress relaxation of the steel is simulated using a viscoelastic model called Generalized Maxwell. A 3D FE model was used, where the nonlinear material behaviour and geometrical analysis based on incremental-iterative load methods were adopted. Validation by comparison with the analytic solution will be done for the case of a concrete beam with a parabolic pre-tensioned steel tendon embedded and some viscoelastic cases are performed in order to perceive the behaviour of the Generalized Maxwell model. Several examples are shown where the capabilities of the method on large scale structures are exhibited.

Methodology for the analysis of post-tensioned structures using a constitutive serial-parallel rule of mixtures: Large scale non-linear analysis

“…In this section, two different large-scale structures that have steel tendons embedded in the concrete structure can be seen. Their elastic behaviour has been shown in [4] and here the nonlinear behaviour will be presented. For the steel tendons, a plasticity model with isotropic hardening has been used while for the concrete an isotropic scalar damage model was chosen.…”

“…Using these compatibility equations in a composite made of matrix and fibre, if the matrix structural capacity is lost due to excessive shear stresses, the isostress condition also reduces the shear capacity of fibre, and, consequently, the composite serial strength is also reduced. The extended formulation for the S-P RoM can be found in [4], together with its algorithm. It is interesting to summarize here the main hypothesis for the numerical formulation: 1.…”

“…Component materials have the same stress in serial direction. 4. Composite material response is in direct relation with the volume fractions of compounding materials.…”

“…The work presented from here on is based on the innovative methodology proposed in [4] for the numerical analysis of pre-stressed and post-tensioned structures. In the aforementioned paper several different techniques have been mentioned as being habitually used when numerically calculating prestressed concrete structures.…”

Analysis of the mock-up of a reactor containment building: Comparison with experimental results

“…This article presents the predictive analysis results of the mock-up of a reactor containment building. The computational study performed has been based on the Serial-Parallel Rule of Mixtures (S-P RoM from now on) [2,3,4,5,6,7] which is a technique used in the analysis of composite materials. A complete description of the problem is included and the obtained numerical results are compared with the experimental records showing a good agreement.…”