Prediction of the Thermal Spalling Risk of Concrete Structures During Fire by Means of a Finite Element Model

2009 ◽  
Author(s):  
F. Pesavento ◽  
B.A. Schrefler ◽  
D. Gawin ◽  
J. Principe
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Concrete Structures ◽  
Element Model

scholarly journals Development of Practical Finite Element Models for Collapse of Reinforced Concrete Structures and Experimental Validation

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Mario Bermejo ◽  
Anastasio P. Santos ◽  
José M. Goicolea
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Elements ◽  
Finite Element Model ◽  
Computational Cost ◽  
Concrete Structures ◽  
Element Model ◽  
Reinforced Concrete Structures ◽  
Finite Element Models ◽  
Explicit Finite Element

This paper describes two practical methodologies for modeling the collapse of reinforced concrete structures. They are validated with a real scale test of a two-floor structure which loses a bearing column. The objective is to achieve accurate simulations of collapse phenomena with moderate computational cost. Explicit finite element models are used with Lagrangian meshes, modeling concrete, and steel in a segregated manner. The first model uses 3D continuum finite elements for concrete and beams for steel bars, connected for displacement compatibility using a penalty method. The second model uses structural finite elements, shells for concrete, and beams for steel, connected in common nodes with an eccentricity formulation. Both are capable of simulating correctly the global behavior of the structural collapse. The continuum finite element model is more accurate for interpreting local failure but has an excessive computational cost for a complete building. The structural finite element model proposed has a moderate computational cost, yields sufficiently accurate results, and as a result is the recommended methodology.

Damage identification in concrete structures with uncertain but bounded measurements

2016 ◽  
Vol 16 (6) ◽  
pp. 649-662 ◽  
Author(s):  
Suryakanta Biswal ◽  
Ananth Ramaswamy
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Posterior Probability ◽  
Optimization Technique ◽  
Concrete Structures ◽  
Element Model ◽  
Reinforced Concrete Beams ◽  
Finite Element Software ◽  
Damage Indices ◽  
The Finite Element Model

The major sources of error in the measurements of concrete structures are the gauge sensitivities, calibration accuracies, amplitude linearities, and temperature corrections to the gauge sensitivities, which are given in terms of plus–minus ranges, and the round off errors in the measured responses, which are better represented by interval bounds. An algorithm is proposed adapting the existing modified Metropolis Hastings algorithm for estimating the posterior probability of the damage indices as well as the posterior probability of the bounds of the interval parameters, when the measurements are given in terms of interval bounds. A damage index is defined for each element of the finite element model considering the parameters of each element are intervals. Methods are developed for evaluating response bounds in the finite element software ABAQUS, when the parameters of the finite element model are intervals. The proposed method is validated against reinforced concrete beams with three damage scenarios mainly (1) loss of stiffness, (2) loss of mass, and (3) loss of bond between concrete and reinforcement steel, which have been tested in our laboratory. Comparison of the prediction from the proposed method with those obtained from Bayesian analysis and interval optimization technique show improved accuracy and computational efficiency in addition to better representation of measurement uncertainties through interval bounds.

scholarly journals Rayleigh wave propagation and scattering characteristics at debondings in fibre-reinforced polymer-retrofitted concrete structures

2018 ◽  
Vol 18 (1) ◽  
pp. 303-317 ◽  
Author(s):  
Hasan Mohseni ◽  
Ching-Tai Ng
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Finite Element Model ◽  
Rayleigh Wave ◽  
Wave Scattering ◽  
Three Dimensional ◽  
Concrete Structures ◽  
Element Model ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

Structural health monitoring is of paramount importance to ensure safety and serviceability of structures. Among different damage detection techniques, guided wave–based approach has been the subject of intensive research activities. This article investigates the capability of Rayleigh wave for debonding detection in fibre-reinforced polymer-retrofitted concrete structures through studying wave scattering phenomenon at debonding between fibre-reinforced polymer and concrete. A three-dimensional finite element model is presented to simulate Rayleigh wave propagation and scattering at the debonding. Numerical simulations of Rayleigh wave propagation are validated with analytical solutions. Absorbing layers by increasing damping is employed in the fibre-reinforced polymer-retrofitted concrete numerical model to maximise computational efficiency in the scattering study. Experimental measurements are also carried out using a three-dimensional laser Doppler vibrometer to validate the three-dimensional finite element model. Very good agreement is observed between the numerical and experimental results. The experimentally and analytically validated finite element model is then used in numerical case studies to investigate the wave scattering characteristic at the debonding. The study investigates the directivity patterns of scattered Rayleigh waves, in both backward and forward directions, with respect to different debonding size-to-wavelength ratios. This study also investigates the suitability of using bonded mass to simulate debonding in the fibre-reinforced polymer-retrofitted concrete structures. By enhancing physical understanding of Rayleigh wave scattering at the debonding between fibre-reinforced polymer/concrete interfaces, this study can lead to further advance of Rayleigh wave–based damage detection techniques.

Modeling Concrete Material Structure: A Two-Phase Meso Finite Element Model

2017 ◽  
Vol 08 (02) ◽  
pp. 1750004 ◽  
Author(s):  
E. A. Bonifaz ◽  
Juan Baus ◽  
Eva O. L. Lantsoght
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cement Paste ◽  
Concrete Structures ◽  
Element Model ◽  
Material Structure ◽  
Hydrated Cement ◽  
Stress Strain ◽  
Meso Level ◽  
Hydrated Cement Paste

Concrete is a compound material where aggregates are randomly placed within the cement paste. To describe the behavior of concrete structures at the ultimate, it is necessary to use nonlinear finite element models, which for shear and torsion problems do not always give satisfactory results. The current study aims at improving the modeling of concrete at the meso-level, which eventually can result in an improved assessment of existing structures. Concrete as a heterogeneous material is modeled consisting of hydrated cement paste and aggregates. The stress–strain curves of the hydrated cement paste and aggregates are described with results from the literature. A three-dimensional (3D) finite element model was developed to determine the influence of individual phases on the inelastic stress–strain distribution of concrete structures. A random distribution and morphology of the cement and aggregate fractions are achieved by using DREAM.3D. Two affordable computational dual-phase representative volume elements (RVEs) are imported to ABAQUS to be studied in compression and tension. The virtual specimens (concrete mesh) subjected to continuous monotonic strain loading conditions were constrained with 3D boundary conditions. Results demonstrate differences in stress–strain mechanical behavior in both compression and tension test simulations. A strong dependency of flow stress and plastic strain on phase type, aggregate (andesite) size, shape and distribution upon the composite local response are clearly observed. It is noted that the resistance to flow is higher in concrete meshes composed of finer and homogeneous aggregate particles because the Misses stresses and effective plastic strains are better distributed. This study shows that at the meso-level, concrete can be modeled consisting of aggregates and hydrated cement paste.

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