scholarly journals Influence of imperfections in the buckling resistance of steel beam-columns under fire

2021 ◽  
Author(s):  
Samer Nemer ◽  
Ferenc Papp
Keyword(s):  
Elevated Temperatures ◽  
Load Capacity ◽  
Element Model ◽  
Imperfection Sensitivity ◽  
Ultimate Load Capacity ◽  
Geometric Imperfection ◽  
Beam Columns ◽  
Buckling Resistance ◽  
Global And Local ◽  
Structural Imperfections

AbstractThis paper presents an investigation on the influence of structural imperfections on the ultimate load capacity of steel welded beam-columns with class 4 cross-section under elevated temperatures. This is done by considering different amplitudes for the global and local (plate) imperfections, and different residual stresses distributions available in the literature. To this purpose, a geometrically and materially non-linear finite element model using Abaqus software has been used to determine the buckling resistance of a steel welded beam-column at elevated temperatures, using the material properties of EN1993-1-2. The imperfection sensitivity of beam-columns is reported: the influences of the amplitudes of the geometric imperfection and the patterns of the residual stress on the load capacity are compared.

Experimental and numerical investigation of slabs on ground subjected to concentrated loads

2014 ◽  
Vol 4 (3) ◽  
Author(s):  
Jan Øverli
Keyword(s):  
Finite Element ◽  
Load Capacity ◽  
Drying Shrinkage ◽  
Element Model ◽  
Experimental Program ◽  
Ultimate Load Capacity ◽  
Smeared Crack Approach ◽  
Linear Behaviour ◽  
Smeared Crack ◽  
Slabs On Ground

AbstractAn experimental program is presented where a slab on ground is subjected to concentrated loading at the centre, the edges and at the corners. Analytical solutions for the ultimate load capacity fit well with the results obtained in the tests. The non-linear behaviour of the slab is captured by performing nonlinear finite element analyses. The soil is modelled as a no-tension bedding and a smeared crack approach is employed for the concrete. Through a parametric study, the finite element model has been used to assess the influence of subgrade stiffness and shrinkage. The results indicate that drying shrinkage can cause severe cracking in slabs on grade.

scholarly journals Ultimate Strength Assessment of Steel-Welded Hemispheres under External Hydrostatic Pressure

2021 ◽  
Author(s):  
Sang-Rai Cho ◽  
Teguh Muttaqie ◽  
Seung Hyun Lee ◽  
Jaewoo Paek ◽  
Jung Min Sohn
Keyword(s):  
Hydrostatic Pressure ◽  
Load Capacity ◽  
External Hydrostatic Pressure ◽  
Ultimate Load Capacity ◽  
Initial Shape ◽  
Strength Assessment ◽  
Geometric Imperfection ◽  
Collapse Pressure ◽  
Hemispherical Shells ◽  
Shape Imperfection

AbstractThis paper focusses on steel-welded hemispherical shells subjected to external hydrostatic pressure. The experimental and numerical investigations were performed to study their failure behaviour. The model was fabricated from mild steel and made through press forming and welding. We therefore considered the effect of initial shape imperfection, variation of thickness and residual stress obtained from the actual structures. Four hemisphere models designed with R/t from 50 to 130 were tested until failure. Prior to the test, the actual geometric imperfection and shell thickness were carefully measured. The comparisons of available design codes (PD 5500, ABS, DNV-GL) in calculating the collapse pressure were also highlighted against the available published test data on steel-welded hemispheres. Furthermore, the nonlinear FE simulations were also conducted to substantiate the ultimate load capacity and plastic deformation of the models that were tested. Parametric dependence of the level of sphericity, varying thickness and residual welding stresses were also numerically considered in the benchmark studies. The structure behaviour from the experiments was used to verify the numerical analysis. In this work, both collapse pressure and failure mode in the numerical model were consistent with the experimental model.

Finite Element Analysis of the Corrosion Prestressed Concrete Beam

2012 ◽  
Vol 204-208 ◽  
pp. 3040-3043
Author(s):  
Hong Bo Zou ◽  
Xiao Yong Luo
Keyword(s):  
Finite Element ◽  
Corrosion Rate ◽  
Prestressed Concrete ◽  
Concrete Beam ◽  
Mechanical Performance ◽  
Load Capacity ◽  
Element Model ◽  
Ultimate Load Capacity ◽  
Element Analysis ◽  
Prestressed Concrete Beam

Based on analysis of the Corrosion prestressed concrete beam with finite element model, the paper presents the mechanical performance of concrete beams in different corrosion rates. When the corrosion rate is less than 5%, the strand corrosion has little impact on the load capacity. With the increase of the corrosion rate more than 5%, what damage happened to Beam is little steel damage and brittle damage even without apparent warning and at the same time the Corrosion of steel strand will cause the decrease of the ultimate load capacity with the deterioration of ductility.

scholarly journals Flexural Behavior of Reinforced Concrete Beams Covered by Gypsum Layers and Exposed to Elevated Temperatures

2021 ◽  
Vol 318 ◽  
pp. 03005
Author(s):  
Raid Sattar warwar ◽  
AbdulMuttalib I. said
Keyword(s):  
Outer Surface ◽  
Elevated Temperatures ◽  
Load Capacity ◽  
Concrete Surface ◽  
Reinforced Concrete Beams ◽  
Flexural Behavior ◽  
Ultimate Load Capacity ◽  
Direct Exposure ◽  
Experimental Side ◽  
The Relationship

The paper presents results of exposure of normal concrete to elevated temperatures (400 and 700) °C covered by layers (gypsum and plaster) with different thicknesses (10 and 20) mm. The casted specimens for each type of test were divided into three groups. The first was without covering the concrete surface with gypsum, while the second and third groups were covered with gypsum of the outer surface with a thickness of 10 and 20 mm, respectively. The experimental results found that the ultimate load capacity and the first crack load of RC beams were improved by using gypsum layers through 400°C. At thickness 10 and 20 mm, the (Pcr and Pu) loss was about (8 and 6) % and (1 and 7) % respectively, compared to the concrete not covered with gypsum, the loss rate is about (25 and 13) %, and this is clear evidence of the benefit of gypsum in reducing the Elevated Temperatures directly to concrete. As for the temperature of 700, the reduction in (Pcr and Pu) was about (57 and 22) % and (31 and 16) % and (10 and 15) % at 0, 10, 20 mm gypsum thickness, respectively. Through the figures shown in the paper, which were obtained from the experimental side of the research, the load-deflection curves improved when the gypsum thickness increased during the specimens' exposure to fire. Where the relationship between them at a temperature of 400°C in a thickness of 20 mm was better than 10 mm when exposed to fire, so by increasing the thickness of the gypsum, the occurrence of deflection is less because it protects the surface of the concrete from direct exposure to heat and thus prevents the occurrence of cracks in the outer surface of the concrete.

An analytical model for the behavior of I-shaped beam to cylindrical column connections at room temperature and high temperatures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Seied Ahmad Hosseini ◽  
Mostafa Zeinoddini
Keyword(s):  
Analytical Solution ◽  
Elevated Temperatures ◽  
Element Model ◽  
Small Scale ◽  
Offshore Platforms ◽  
Rotational Stiffness ◽  
Rotation Curves ◽  
Content Type ◽  
Shaped Beam ◽  
Cylindrical Column

PurposeIn this paper, a closed-form analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections, commonly used on offshore platforms, at room and elevated temperatures, are presented.Design/methodology/approachAn analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections is presented. The results of this model are compared with those of a non-linear coupled mechanical-thermal finite element model and small-scale experimental tests previously provided by the authors.FindingsIn this paper, a closed-form analytical solution for the prediction of moment-rotation and the rotational stiffness-rotation curves of I-shaped beam to cylindrical column connections, commonly used on offshore platforms, at room and elevated temperatures, is presented. The required yield and plastic moments in this model are provided as an extension to Roark's relationships. The results of this model are compared with those of a non-linear coupled mechanical-thermal finite element model and small-scale experimental tests previously provided by the authors. A reasonable agreement has been found between the analytical model results and the experimental/numerical modeling results.Originality/valueThis article is extracted from the author’s doctoral thesis, and all its achievements belong to the authors of the article.

A new method of buckling resistance evaluation of laterally restrained beam-columns

2016 ◽  
pp. 197-205
Author(s):  
M Gizejowski ◽  
Z Stachura ◽  
M Gajewski ◽  
R Szczerba
Keyword(s):  
New Method ◽  
Resistance Evaluation ◽  
Beam Columns ◽  
Buckling Resistance

scholarly journals Response of the Flat Reinforced Concrete Floor Slab with Openings under Cyclic In-Plane Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Eden Shukri Kalib ◽  
Yohannes Werkina Shewalul
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Lateral Displacement ◽  
Load Capacity ◽  
Element Model ◽  
Absorption Capacity ◽  
Hysteretic Behavior ◽  
Element Analysis ◽  
Floor Slab ◽  
Floor Slabs

The responses of flat reinforced concrete (RC) floor slabs with openings subjected to horizontal in-plane cyclic loads in addition to vertical service loads were investigated using nonlinear finite element analysis (FEA). A finite element model (FEM) was designed to perform a parametric analysis. The effects of opening sizes (7%, 14%, 25%, and 30% of the total area of the slab), opening shapes (elliptical, circular, L-shaped, T-shaped, cross, and rectangular), and location on the hysteretic behavior of the floor slab were considered. The research indicated that openings in RC floor slabs reduce the energy absorption capacity and stiffness of the floor slab. The inclusion of 30% opening on the floor slab causes a 68.5%, 47.3%, and 45.6% drop in lateral load capacity, stiffness, and lateral displacement, respectively, compared to the floor slab with no openings. The flat RC floor slab with a circular opening shape has increased efficiency. The placement of the openings is more desirable by positioning the openings at the intersection of two-column strips.

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