Fully coupled multi-physics nonlinear analysis of structural space frames subjected to fire using the direct stiffness method
TL;DR: In this paper, a fully coupled hydro-thermo-mechanical formulation based on the direct stiffness method for analysis of steel and reinforced concrete structural space frames was developed for space frames.
Abstract: This article develops a fully coupled hydro-thermo-mechanical formulation based on the direct stiffness method for analysis of steel and reinforced concrete structural space frames. The superiority...
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TL;DR: In this article, an approach using corotational layered beam is proposed to mitigate fire risk in reinforced concrete (RC) structures and appropriate structural resistance against it has to be ensured.
Abstract: Fire is a critical risk in reinforced concrete (RC) structures and appropriate structural resistance against it has to be ensured. In this contribution, an approach using corotational layered beam ...
6 citations
Cites background or methods from "Fully coupled multi-physics nonline..."
...Noteworthy recent developments incorporate a two-way thermo-mechanical coupling in 2D (Prakash and Srivastava, 2018b) and 3D (Prakash and Srivastava, 2018a) based on a direct stiffness method....
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...…the generalized strains and is supposed to be the same for both concrete and steel materials, based on a perfect bonding assumption between the steel reinforcements and concrete, as in Balaji et al. (2016), Bamonte and Lo Monte (2015), Kodur and Dwaikat (2008), and Prakash and Srivastava (2018b)....
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...Using the Bernouilli beam theory that neglects shear strains is recognized to be a good approximation for beams with a length/height aspect ratio of roughly over 10 and was shown to yield good results in Kodur and Dwaikat (2008) and Prakash and Srivastava (2018a, 2018b)....
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TL;DR: In this paper , the sensitivity of reinforced concrete structures under fire loading was investigated using a relatively low cost 2D corotational layered beam finite element in a reduced latin hypercube sampling framework.
Abstract: The sensitivity of the structural response to variations of material and cross sectional geometrical parameters is investigated for reinforced concrete structures under fire loading. A relatively low cost 2D corotational layered beam finite element is employed in a reduced latin hypercube sampling framework for this purpose. The structural response is assessed in terms of vertical deflection versus time, failure time and cross sectional stress/strain distribution using standard fire curves. The numerical models represent experimentally tested cases in the literature and operate with experimentally derived parameter sets, when possible. A minimum set of three RVs, the bottom concrete cover thickness, steel and concrete yield stregths, out of the initial full set of 12 are identified that drastically reduces the number of RVs and thus the stochastic computation’s cost, while keeping a reasonable envelop for the results. The relationship between structural behavior, material degradation and data extracted from the cross sectional behavior is also successfully established and used to explain why the random set can be reduced to three parameters.
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TL;DR: In this article, the authors describe the application of thermoplasticity to modeling the response of a nonlinear hardening material (concrete in the present case) under transient temperature and stress, and investigate the effect of a sustained load on the deformational response of concrete under biaxial loading and elevated temperature.
Abstract: In the past, the theory of thermoplasticity has been confined to metal type materials exhibiting an elastic-perfectly-plastic behaviour. This paper describes the application of this theory to modelling the response of a nonlinear hardening material (concrete in the present case) under transient temperature and stress. The difficulties arising from the application of the theory of thermoelastoplasticity to modelling the behaviour of concrete at elevated temperatures are discussed, together with the inadequacy of the existing algorithms that were proposed for perfectly plastic materials, to cope with a nonlinear hardening case. An integration scheme derived from the Euler backward scheme is used to integrate the rate equations. The resulting model is used to analyse existing biaxial data and investigate the effect of a sustained load on the deformational response of concrete under biaxial loading and elevated temperature.
29 citations
TL;DR: In this article, a novel approach to nonlinear finite-element analysis of concrete structures exposed to fire is presented, which uses a special class of evolutionary algorithms, known as cellular automata, to describe the heat transfer process induced by fire and to create an effective link between the simulation of the thermal process and the structural analysis.
Abstract: A novel approach to nonlinear finite-element analysis of concrete structures exposed to fire is presented. The proposed formu- lation refers to frame systems, but it can be extended to other types of structures. The main novelty of this formulation is the use of a special class of evolutionary algorithms, known as cellular automata, to describe the heat transfer process induced by fire and to create an effective link between the simulation of the thermal process and the structural analysis. The heat transfer process is reproduced by considering heat conduction, heat convection, and thermal radiation. The temperature effects on the structural performance are taken into account by means of temperature-dependent thermal and mechanical properties of concrete and steel. In this way, the general criteria for nonlinear finite-element analysis of concrete structures are applied to formulate a cellular reinforced concrete beam element with temperature-dependent character- istics. The effectiveness and applicability in engineering practice of the proposed formulation is demonstrated through applications. The results prove the accuracy of the proposed procedure and show that, for statically indeterminate structures, fire safety needs to be evaluated at the global level by taking into account the actual role played by the structural scheme. DOI: 10.1061/(ASCE)ST.1943-541X.0000307. © 2011 American Society of Civil Engineers. CE Database subject headings: Concrete structures; Finite element method; Fire resistance; Heat transfer; Nonlinear analysis.
28 citations
TL;DR: In this paper, three two-story, single-bay, and sway allowed frames subjected to proportional vertical and horizontal loads were tested and it was observed that the load carrying capacities calculated by the AISC-LRFD method was 25%, conservative when compared with those of the experiment.
23 citations
TL;DR: In this paper, the generalized plastic hinges concept, where normal force and bending moments are considered in the plastification process, is extended to include temperature effects, by means of stiffness reduction factors.
19 citations
TL;DR: In this paper, a 3D eight-noded brick element, which is capable of representing the performance of composite structures subjected to 3D stress conditions at ambient and high temperatures, has been developed and incorporated into a finite-element analysis program.
Abstract: A three-dimensional (3D) eight-noded brick element, which is capable of representing the performance of composite structures subjected to 3D stress conditions at ambient and high temperatures, has been developed and incorporated into a finite-element analysis program Vulcan. In the formulation of this element, geometric nonlinearity, material nonlinearity, material degradation, and thermal expansion at elevated temperatures have been taken into account. The von Mises and Drucker-Prager theories were chosen as the 3D failure criteria for steel and concrete, respectively. In particular, a series of postfailure criteria and corresponding 3D constitutive relations for concrete at high temperatures were defined in this study. The accuracy and efficiency of this newly developed structural element was verified against the results from a number of tests on composite structures subjected to 3D stress conditions at both ambient and elevated temperatures. The proposed 3D structural element can be used to model a large range of composite structures in fire, and perform more detailed studies on them.
16 citations