Effect of concrete slab on the behavior of fire exposed subframe assemblies with bolted double angle connections

Pakala, Purushotham; Kodur, Venkatesh

doi:10.1016/j.engstruct.2015.10.052

Cited by 14 publications

(6 citation statements)

References 24 publications

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“…Multilinear isotropic hardening plasticity model is assumed, since large strains are expected to develop, following stress-strain definitions according to [8] (Figure 4). Mechanical properties of concrete and steel used to generate nominal stress-straintemperature relations are converted into true stress-strain curves, to account for dimensional changes and to provide more realistic representation of the material behaviour [14], using following relations: In general, mesh size does not have to be the same for thermal and structural model, and for structural model is adopted as 5.0 cm, except in the regions of severe thermal gradients (concrete cover), where the element size is reduced to 2.5 cm (Figure 6).…”

Section: Structural Modelmentioning

confidence: 99%

Numerička Simulacija Odgovora Armiranobetonskog Okvira U Požaru

Džolev¹,

Lađinović²

2021

Zbornik GFS

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Reinforced concrete (RC) structures exhibit complex behaviour when subjected to fire. Severe thermal action evokes changes in the material microstructure and thermal-hydral-mechanical properties, depending on the heating rate, moisture, boundary conditions, geometry and size of the heated member, loading type, chemicalphysical interactions, etc. Extensive experimental material research has led to the development of mathematical models and numerical procedures that could, to a certain degree, capture adequately the behaviour of structures under fire conditions. Advanced modelling guidelines have been proposed in standards, such as Eurocode. Based on these recommendations and previous efforts conducted by other researchers, a numerical model is developed in finite element (FE) software ANSYS. The model incorporates temperature dependent physical, thermal and mechanical properties of constituting materials and conducts nonlinear heat transfer and structural analysis, simulating the response of RC frame structure under standard fire action. Explicit modelling of concrete and steel reinforcement allows monitoring of temperature evolution in both concrete and reinforcement elements, deformations, section forces and stresses and strains in reinforcement bars, providing a broad insight into the structural behaviour at both global and local level. Special consideration is given to the influence of fire scenario on RC frame behaviour.

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Section: Structural Modelmentioning

confidence: 99%

Numerička Simulacija Odgovora Armiranobetonskog Okvira U Požaru

Džolev¹,

Lađinović²

2021

Zbornik GFS

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“…Currently, several experimental studies are available on the response of steel bolted connections under fire condition (Lou et al, 2015;Pakala and Kodur, 2016;Sagiroglu, 2018;Cho et al, 2020;Akagwu et al, 2020;Kordosky et al, 2020;Rezaeian and Eghbali, 2021;Wang et al, 2021;Qiang et al, 2022;Ebrahimzadeh and Rezaeian, 2022). Likewise, finite element analysis (FEA) is frequently utilized in the literature due to the high cost, time-consuming and complexities of experimental studies.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, several experimental studies are available on the response of steel bolted connections under fire condition (Lou et al. , 2015; Pakala and Kodur, 2016; Sagiroglu, 2018; Cho et al. , 2020; Akagwu et al.…”

Section: Introductionmentioning

confidence: 99%

Simulation of bolted connections under fire: optimization and model validation

Saglik

Chen

2023

JSFE

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PurposeBeginners and even experienced ones have difficulties in completing the structural fire analysis due to numerical difficulties such as convergence errors and singularity and have to spend a lot of time making many repetitive changes on the model. The aim of this article is to highlight the advantages of explicit solver which can eliminate the mentioned difficulties in finite element analysis containing highly nonlinear contacts, clearance between modeled parts at the beginning and large deflections because of high temperature. This article provides important information, especially for researchers and engineers who are new to structural fire analysis.Design/methodology/approachThe finite element method is utilized to achieve mentioned purposes. First, a comparative study is conducted between implicit and explicit solvers by using Abaqus. Then, a validation process is carried out to illustrate the explicit process by using sequentially coupled heat transfer and structural analysis.FindingsExplicit analysis offers an easier solution than implicit analysis for modeling multi-bolted connections under high temperatures. An optimum mesh density for bolted connections is presented to reflect the realistic structural behavior. Presented explicit process with the offered mesh density is used in the validation of an experimental study on multi-bolted splice connection under ISO 834 standard fire curve. A good agreement is achieved.Originality/valueWhat makes the study valuable is that the points to be considered in the structural fire analysis are examined and it is a guide that future researchers can benefit from. This is especially true for modeling and analysis of multi-bolted connections in finite element software under high temperatures. The article can help to shorten and even eliminate the iterative debugging phases, which is a problematic and very time-consuming process for many researchers.

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“…The behavior of steel connections in fire conditions is significantly influenced by interactions between connected constructional members, along with the thermal and mechanical properties of the joint components, structural continuity and nature of fire (Pakala and Kodur, 2016; Zahmatkesh et al ., 2019; Pournaghshband et al ., 2019; Mahamid et al ., 2019; Suman and Samanta, 2021). Therefore, when the isolated connections are considered in research, the effects of the temperature variation on the connection forces, and large deformation in the connected beam are ignored (Bailey et al ., 1996; Yahyai and Rezaeian, 2015; Eslami et al ., 2018; Rezaeian and Eghbali, 2021).…”

Section: Introductionmentioning

confidence: 99%

Performance of steel beam with welded top-seat angle connections at elevated temperatures

Rezaeian

Mansoori

Khajehdezfuly

2023

JSFE

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PurposeTop-seat angle connection is known as one of the usual uncomplicated beam-to-column joints used in steel structures. This article investigates the fire performance of welded top-seat angle connections.Design/methodology/approachA finite element (FE) model, including nonlinear contact interactions, high-temperature properties of steel, and material and geometric nonlinearities was created for accomplishing the fire performance analysis. The FE model was verified by comparing its simulation results with test data. Using the verified model, 24 steel-framed top-seat angle connection assemblies are modeled. Parametric studies were performed employing the verified FE model to study the influence of critical factors on the performance of steel beams and their welded angle joints.FindingsThe results obtained from the parametric studies illustrate that decreasing the gap size and the top angle size and increasing the top angles thickness affect fire behavior of top-seat angle joints and decrease the beam deflection by about 16% at temperatures beyond 570 °C. Also, the fire-resistance rating of the beam with seat angle stiffener increases about 15%, compared to those with and without the web stiffener. The failure of the beam happens when the deflections become more than span/30 at temperatures beyond 576 °C. Results also show that load type, load ratio and axial stiffness levels significantly control the fire performance of the beam with top-seat angle connections in semi-rigid steel frames.Originality/valueDevelopment of design methodologies for these joints and connected beam in fire conditions is delayed by current building codes due to the lack of adequate understanding of fire behavior of steel beams with welded top-seat angle connections.

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Effect of concrete slab on the behavior of fire exposed subframe assemblies with bolted double angle connections

Cited by 14 publications

References 24 publications

Numerička Simulacija Odgovora Armiranobetonskog Okvira U Požaru

Numerička Simulacija Odgovora Armiranobetonskog Okvira U Požaru

Simulation of bolted connections under fire: optimization and model validation

Performance of steel beam with welded top-seat angle connections at elevated temperatures

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