Analysis of Reinforced Concrete Structures using a Cluster of PCs

This paper considers the practical application of nonlinear models in the analysis of reinforced concrete structures. The results of some analyses performed using the reinforced concrete model of the general purpose finite element code Ansys are presented and discussed. The differences observed in the response of the same reinforced concrete beam as some variations are made in a material model that is always basically the same are emphasyzed. The consequences of small changes in modelling are discussed and it is shown that satisfactory results may be obtained from relatively simple and limited models.

This paper considers the practical application of nonlinear models in the analysis of reinforced concrete structures. The results of some analyses performed using the reinforced concrete model of the general purpose finite element code Ansys are presented and discussed. The differences observed in the response of the same reinforced concrete beam as some variations are made in a material model that is always basically the same are emphasyzed. The consequences of small changes in modelling are discussed and it is shown that satisfactory results may be obtained from relatively simple and limited models.

The non-linear behavior of reinforced concrete (RC) beams till the ultimate failure is a complicated phenomenon due to the involvement of heterogenic material properties and cracking behavior of concrete. Behavior prediction of reinforced concrete elements till failure is usually carried out using experimental testing, and the observations are recorded only at critical locations due to restriction in cost of testing equipment and accessories. In order to avoid the destructive testing, reduction of the cost of materials and manpower, the behavior prediction of RC beams is generally carried out using numerical methods. This paper presents study on non-linear flexural behavior of reinforced concrete beams. Non-linear finite element analysis of reinforced concrete beams under flexural loading is presented in this paper. Finite element modelling of reinforced concrete beams is carried out using discrete reinforcement modelling technique. The capability of the model to capture the critical crack regions, loads and deflections for various loadings in reinforced concrete beam has been illustrated. Comparison is made between the experimental results and finite element analyses with respect to initial crack formation and the ultimate load capacity of beams. The results obtained in the present study show close agreement with those in the available literature.

2004

There has been considerable research on modelling inelastic behaviour of reinforced concrete. However, nonlinear material models used for seismic response history analyses and for nonlinear static analysis (NSA) procedures tend to be simple. It can be argued that sophisticated material models for a complex material like reinforced concrete are perhaps not essential for earthquake analysis in view of several other uncertainties associated with the seismic phenomenon. This paper examines the influence of material modelling on RHA responses for a simple reinforced concrete frame structure. Five acceleration time histories compatible to elastic design spectrum of Eurocode 8 are used for RHA. Two material models are considered: a concrete damaged plasticity model that uses the Drucker Prager criterion and in which concrete and reinforcement are modelled separately and a homogenized Drucker Prager model. In both cases the influence of strain hardening and strain rate effects are considered. The results show that the design response from RHA analyses is significantly different for the two models. The paper then compares the NSA and RHA responses for the two material models for reinforced concrete. The NSA procedures considered are the Displacement Coefficient Method (DCM) and the Capacity Spectrum Method (CSM). A comparison of RHA and NSA procedures shows that there can be a significant difference in local response even though the target deformation values at the control node match. Moreover, the difference between the mean peak RHA response and the pushover response is not independent of the material model.

2013

It generally accepted that most building structures shall exhibit a nonlinear response when subjected to medium-high intensity earthquakes. It is currently known, however, that this phenomenon is not properly modelled in the majority of cases, especially at the design stage, where only simple linear methods have effectively been used. Recently, as a result of the exponential progress of computational tools, nonlinear modelling and analysis have gradually been brought to a more promising level. A wide range of modelling alternatives developed over the years is hence at the designer's disposal for the seismic design and assessment of engineering structures. The objective of the study presented herein is to test some of these models in an existing structure, and observe their performance in nonlinear static and dynamic analyses. This evaluation is done by the use of two of a known range of advanced computer programs: SAP2000 and SeismoStruct. The different models will focus on the element flexural mechanism with both lumped and distributed plasticity element models. In order to appraise the reliability and feasibility of each alternative, the programs capabilities and the amount of labour and time required for modelling and performing the analyses are also discussed. The results obtained show the difficulties that may be met, not only in performing nonlinear analyses, but also on their dependency on both the chosen nonlinear structural models and the adopted computer programs. It is then suggested that these procedures should only be used by experienced designers, provided that they are aware of these difficulties and with a critical stance towards the result of the analyses.

An analytical model, which can simulate the biaxial description of the nonlinear behavior of reinforced concrete structures, is introduced. The behavior of concrete is assumed orthotropic inside the ultimate failure surface and a compressive softening law of concrete is presented. The behavior of cracked concrete is simulated using the smeared crack model, which the tension stiffening effect based on a cracking criterion derived from the fracture mechanics principles is considered. A computer program is developed for analyzing the over and under-reinforced concrete beams. Several parameters such as the non-linearity proprieties, the cut off and tension stiffening models and shear retention factor are studied. The correlation between analytical and experimental results shows the validity of the proposed models and the significance of various effects. The global responses are evaluated to verify simultaneously the reliability of the proposed model and the performance of the numerical program.

Revue européenne des éléments finis, 2004

An analytical model, which can simulate the biaxial description of the nonlinear behavior of reinforced concrete structures, is introduced. The behavior of concrete is assumed orthotropic inside the ultimate failure surface and a compressive softening law of concrete is presented. The behavior of cracked concrete is simulated using the smeared crack model, which the tension stiffening effect based on a cracking criterion derived from the fracture mechanics principles is considered. A computer program is developed for analyzing the over and under-reinforced concrete beams. Several parameters such as the non-linearity proprieties, the cut off and tension stiffening models and shear retention factor are studied. The correlation between analytical and experimental results shows the validity of the proposed models and the significance of various effects. The global responses are evaluated to verify simultaneously the reliability of the proposed model and the performance of the numerical program.

Revista IBRACON de Estruturas e Materiais, 2014

The analysis of reinforced concrete structures until failure requires the consideration of geometric and material nonlinearities. However, nonlinear analysis is much more complex and costly than linear analysis. In order to obtain a computationally efficient approach to nonlinear analysis of reinforced concrete structures, this work presents the formulation of a nonlinear plane frame element. Geometric nonlinearity is considered using the co-rotational approach and material nonlinearity is included using appropriate constitutive relations for concrete and steel. The integration of stress resultants and tangent constitutive matrix is carried out by the automatic subdivision of the cross-section and the application of the Gauss quadrature in each subdivision. The formulation and computational implementation are validated using experimental results available in the literature. Excellent results were obtained.

2015

This work aims to develop and identify a new model for reinforced concrete joint element subject to cyclic loadings. Based on experiments and 3D numerical modeling, a simplified model of RC beam-column joint is introduced (within the framework of macro-element). In a first experimental study, this joint will be tested under reverse cyclic loading applied at the beam tip to identify its behavior under this kind of loading in terms of strength, stiffness and ductility. In parallel of experiments, a finite elements model of the joint based on 3D finite elements is presented to highlight and define the nonlinear mechanisms involved in the ruin of the assembly. This step will confirm the experimentally observed phenomena: damage, friction, plasticity. Secondly, a simplified macro-element model for beam-column joint, associated to a nonlinear behavior, is introduced to reflect the response of the joint under cyclic loading loads. Model parameters will be identified from experimental resul...

Computers & Structures, 1994

Ahatmct-A numerical method is developed for the analysis of reinforced concrete (RC) plane frames considering the nonlinear material behavior throughout the range of monotonic load applications. Economic and exact formulations for section analysis and frame element modelling together with a suitable solution strategy and technique are adopted to construct an accurate and efficient analysis algorithm which could contribute to a more economic design of RC frames. The analysis procedure is demonstrated through the application of three examples in which its accuracy and etIiciency in comparison with experimental and other analytical results are verified. 62, 331-336 (1967).