Steel I-beams Research Articles

Numerical study of the effects of flange damage on the steel beam capacity under static and fatigue flexural loads

Steel structural sections can get damaged owing to several factors, including natural and operational factors. This damage affects both the structural element's resistance to external static loads and the number of load cycles in fatigue loading. The impact of this damage depends on the percentage, location, and the type of stress applied. Damaged steel I-beams were studied in the lower flange and under static loads only. In this study, a finite element (FE) simulation is performed to investigate the effect of damage on the upper and lower flanges of steel I-beams and the effect on the maximum flexural load capacity and number of load cycles. The maximum flexural load capacity was measured with the shape of the stress distribution through the cross-section at the location of the damage. For validation, the obtained FE analysis results are compared with those of six steel beam specimens from previously published experimental tests. The results demonstrate that numerical analysis can accurately simulate these elements. Moreover, the maximum flexural capacity is unaffected when the damage to the lower beam flange is less than 20%. The location of any percentage of damage to the upper flange directly affects the efficiency of the beam. The damage has a greater impact on the number of load cycles than on the maximum flexural load capacity. The load cycles decreased by 90.5%, with 40% damage on the lower beam flange. Thus, the effect of the stress concentration should be considered when calculating the number of load cycles.

The influence of bracing on the stress state of the ribbed-ring dome framework

The aim of current research was to establish the relationship between the stress state of the ribbed-ring dome framework and the degree of its bracing. It was assumed that the meridional ribs and rings of the dome framework are made of metal. The framework of the dome consists of 24 ribs and 7 rings. The study was performed for a ribbed-ring dome of spherical shape with a span of 39.3 m and a height of 11.0 m on computer models. The initial computer model of the framework of a ribbed-ring dome made of steel I-beams without bracing has been developed. On the basis of the initial model, additional models were developed for the frameworks with bracing between meridional edges in four, eight cyclically symmetric sectors and in all sectors. Both for the initial model and for all models of the dome framework with bracing, computer calculations were performed for the effect of the load from the own weight of the load-bearing and enclosing structures, and two variants of the snow load. During the calculations, deformations, internal forces and stresses in the meridional ribs, upper and intermediate rings of different models were determined, which were compared with each other. Graphs of changes in deformations of the frame, graphs and diagrams of changes in internal forces and stresses in the meridional ribs, in the upper and intermediate rings of the dome, depending on the degree of bracing in the framework, are obtained. An assessment of the influence of bracing on the stress state of the rib-ring dome frame is performed. The peculiarities of the influence of different coupling schemes on the stressed state of the dome frame are noted.

Test Study on Strength of Laser Additive Manufacture AF1410 Steel I-Shaped Beam

The static and fatigue strength of laser additive manufactured AF1410 steel I-beam were tested by a four-point bending test, and the same method was used to test the conventional forged, machined AF1410 short steel beams. The fatigues test data of both short beams were analyzed by DFR method. The test and analysis results show that the static strength of laser additive short beams is close to conventionally fabricated short beams, and the fatigue performance is weaker than that of forged, machined short beams.

Elastic lateral-torsional buckling behavior of steel I-beams with sinusoidal web openings

Recent advances in the production of perforated steel profiles have given rise to the emergence of new opening patterns, among which the sinusoidal pattern stands out. Profiles manufactured with this type of opening are usually used to overcome large free spans and they have a cross-section height considerably higher in relation to the plain-webbed profile that originates them. Due to this, profiles of this nature are more susceptible to failure by lateral-torsional buckling. However, not enough research is found on this type of profile, especially in relation to global instability. In addition, the existing lack of consensus in determining the critical moment in alveolar beams is amplified when considering the openings in a sinusoidal pattern. Therefore, the present work consisted of a numerical evaluation of the elastic stability behavior of these elements through ABAQUS software, in which an extensive parametric study was developed with 15,205 finite element models. Through the parametric study, it was possible to evaluate the influence of several geometric parameters of these beams in the critical moment, as well as to propose an analytical calculation method suitable for beams with sinusoidal openings, considering different loading conditions, which showed excellent compliance with the numerical results.

A Study on the Influence of Bolt Arrangement Parameters on the Bending Behavior of Timber–Steel Composite (TSC) Beams

The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber–steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber–steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load–midspan deflection curve, and load–midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber–steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber–steel interfaces were in the range of 2–6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen’s flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 × 10−3. Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices.

CCTV Camera Array for the Displacement and Strain Measurement of a Beam Specimen in a Laboratory

The available conventional sensors, like displacement transducers, used in the Structural Engineering Laboratory are expensive. In addition to that, the need for data acquisition devices also escalates the expense invested in point contact measurement systems. The recent appeal of vision-based measurement and the search for cost-effectiveness has led to an exploration of the established sampling moiré method using cheap closed-circuit television (CCTV) cameras as a viable option. The sampling moiré method is simple and analyzes the displacements from grating images by a phase-shifting method. Several trial experiments were conducted, which demonstrated that the setup is at least as accurate as the traditional measuring system. An experiment was conducted on a steel I-beam for displacement measurement, which displayed satisfactory results. In addition, the setup was also tested for strain measurement, and it has yielded promising results that need fine-tuning. This paper discusses the challenges, findings, and the possibility of incorporating vision-based displacement measurements in laboratory platforms.

Features of the Stressed-Strain State of a Steel-Reinforced-Concrete Span Structure with Preliminary Bending of a Steel Beam

Purpose. The authors aim to determine the features of the operation of a steel-reinforced concrete span structure with beams reinforced with an I-beam, with their pre-stressing using the bending of a steel I-beam. Methodology. To manufacture a steel-reinforced concrete span structure, it was proposed to reinforce an I-beam with a camber, which is then leveled with the help of applied external loads. For practical convenience, the vertical external forces are replaced by horizontal forces that keep the metal I-beam in a deformed state and in this state it is concreted. After the concrete strength development, the external forces are removed and the metal I-beam creates the pre-stressing of the concrete. Findings. When determining stresses, checking calculations by analytical method and the method of modeling with the help of the ANSYS program were used. The stress diagrams along the lower and upper fibers of a metal I-beam and stresses in concrete in the upper and lower zones of the beam were constructed. The analysis of the results showed that the pre-bending of a metal beam can be used to create a pre-stressing, which improves the performance of steel-reinforced concrete span structures, increases their rigidity and allows using of such a structure to increase the balks of railway and highway bridges. Originality. In the paper, a study of the stress-strain state of steel-reinforced concrete beams of the railway span structure was carried out, taking into account the pre-stressing of the concrete. A method of manufacturing a steel-reinforced concrete beams is proposed, which provides pre-stressing of the reinforced concrete due to the bending of a steel I-beam. Practical value. As a result of the calculations, it was found that the structure, when manufactured by the specified method, has greater rigidity compared to reinforced concrete or metal beams. The height of the beam can be lower compared to reinforced concrete or metal span structures. These circumstances are essential for railway bridges, especially for high-speed traffic ones.

New formulas for predicting the lateral–torsional buckling strength of steel I-beams with sinusoidal web openings

Lateral torsional buckling (LTB) of steel I-beams is characterized by simultaneous lateral deflection and twist. LTB is an instability failure mode that has been intensively investigated. However, existing standard procedures and formulations still have limitations in determining the LTB ultimate moment, especially when considering the use of perforated beams. Consequently, in the current paper, by conducting an extensive parametric study, it was tried to investigate the effect of all main parameters as well as the effect of different loading conditions on the ultimate LTB resistance of steel I-beams with sinusoidal web openings. Then, based on the provided database, the artificial neural network (ANN) method was employed, and based on it, a high-precision formulation was proposed to predict the ultimate LTB strength of steel I-beams. In addition to the ANN method, a regression-based formula was also developed as a classical method to examine the differences between the two methods. Finally, the proposed formulas were compared with other existing formulas for estimating the LTB strength. The results showed that the proposed formula based on ANN not only present a reasonable accuracy compared to the existing formulations but also can be used by engineers as practical equations in the design of I-beams with sinusoidal web openings.

Seismic performances of the joint between replaceable-coupling beams and composite shear wall

Double-skin composite shear walls (DSCSW) have been widely used in high-rise buildings. A novel joint between the replaceable coupling beam (RCB) and the DSCSW (RCB-to-DSCSW joint) was proposed, and its seismic behavior was investigated. Three specimens with varying lengths of the embedded steel I-beam were subjected to a quasi-static test. The damage mode of the joint includes local buckling of the faceplate, tensile fracture of the faceplate butt weld, and concrete crushing. The tensile fracture of the faceplate weld and the concrete crushing significantly affect the ductility of joints. An increase in the length of the embedded I-beam improves the transfer of external loads to the interior of wall pier. In addition, the specimen with a longer steel I-beam (CJ-3) exhibits higher initial stiffness, strength, and ductility. The cumulative energy consumption of CJ-3 was the highest for the same rotation of loading. A simplified method to calculate the joint bearing capacity according to the components' stress patterns was proposed and validated.

OPTIMAL HEIGHT OF STEEL I-BEAMS WITH CHANGING THE WIDTH OF THE FLANGES

The article improves the methodological approach to finding the best constructive solution for a beam made of welded steel I-beams with a variable flange width. An idealized physicalmathematical model of the construction of a beam made of welded steel I-beams with a tapered flange depending on the consumption of steel and changes in the geometric characteristics of the cross-section is described. The bending strength conditions of the beam are taken as limitations. The purpose of the research was to develop an approach to establish the regularity of a rational constructive solution depending on the variability of the width of the flanges of the elastic steel I-beam along its length.It is shown that determining the pattern of changes in the stress-strain state of steel beams with variable shelf width at a constant cross-section height is an urgent task. As a result on the optimal consumption of steel for the structure is shown. A pattern hasbeen established between the variable parameter of the width of the flanges and the coordinate of the calculated section. The effect of displacement of the calculated section of the beams in the direction of a decrease in the geometric characteristics of thebeams, depending on the degree of variability of the width of the shelf along the length of the beam, has been confirmed. Thus, in beams with a variable shelf width at a constant wall height, the maximum stresses occur in the cross-section that does not havethe maximum geometric characteristics.Analytical dependences of determining the optimal height depending on the variability of the width of the flanges were obtained. The methodology of research in the search for a rationalconstructive solution is described. It is shown that in the case of the variability of the width of the flanges, the parameter of the optimal height of the beam depends on the load distribution unction along the length of the beam.A cantilever-clamped elastic beam of I-beam cross-section was studied. Through the relative parameter of the variability of geometric characteristics, it is shown that when the parameterof the variability of the shelf width is changed, the calculated cross-section moves toward the free end with smaller geometric characteristics.Corresponding numerical studies have been carried out, which are illustrated by graphs. The conducted research allows choosing theoptimal dimensions of a steel welded I-beam by changing the width of the flanges that perceive bending moments. According to the research results, the degree of variability of the cross-sectionis recommended for rational designs of steel Ibeams by changing the width of the flanges.

ANALYSIS OF THE STRESS-STRAIN STATE OF A FIRE-RESISTANT STEEL FLOOR BEAM

he article presents an improved methodology for numerical modeling of steelstructural elements on the example of a floor beam, taking into account the influence of fire protection material. The article describes a step-by-stepmethodology for calculating fire resistance in LIRA-SAPR software, which shows in detail the principles of fire resistance analysis.This methodology takes into account the nonlinear dependence of changes in the main thermal and technical characteristics of materials, such as the coefficient of thermal conductivity, heat capacity and convective heat transfer, on temperature. The influence of fire protection deformation characteristics of structural elementswas analyzed.The article also describes the distribution of temperature fields over the elements of the experimental section and investigates the change in temperature and strength characteristics of the steel I-beam of the floor as a function of time. Several options for fire protection using materials from a Ukrainian manufacturer are proposed. Theeffectiveness of the above materials is numerically verified. The analysis results of different fire protection options are compared, which allows you to choose the most optimal option. The results of analysis with and without taking into account thenonlinearity of materials are also compared and described. In addition, the article investigates the role of the floor slab as a fire protection material.This makes it possible to determine the influence of the floor slab on the fire resistance of the structure and provide an additional level of safety.The article will be useful for design engineers who work with steel structures, as well as for researchers interested in the impact of fire protection materials on fire resistance. It provides valuable scientific and practical information that can be used to improve the safety and reliability of steel structures in fire-resistant environments.

Two-stage damage identification method based on fractal theory and whale optimization algorithm

Structural damage identification based on time domain method of vibration response has been widely developed in the recent decades, however, it still confronts some difficulties, such as measurement noise and model error. This paper proposes a novel two-stage damage identification method based on fractal dimension and whale optimization algorithm (WOA). In this study, based on vibration data, the difference in curvature of fractal dimension (DCFD) is used as the damage index to identify the location of suspicious damage elements in the first stage. A new objective function is proposed based on the curvature of fractal dimension (CFD) of acceleration signal, and the WOA is used to estimate the severity of the suspicious damaged element in the second stage. Firstly, the validity of the proposed method is verified by a numerical simply supported beam, and the results exhibit good damage identification ability. Then different noise levels (5% ~ 20%) are introduced into the dynamic responses to verify its robustness, the result shows that the method is of good anti-noise ability in the first stage. Although the second stage is slightly sensitive to noise, it can still effectively identify the severity of damage. Secondly, the vibration testing of a steel I-beam is designed to verify the rationality of the method in the application of actual structure. Finally, based on the simulated vibration test data of the I-40 Bridge, the applicability of the method to complex civil structure is verified, which shows that the method still has good ability to identify the location and severity of damage in complex structure and is of great significance in practical application.

Fire design of stainless steel I beams prone to lateral torsional buckling under end moments

It is known that the loading type significantly influences the resistance of steel I-beams to lateral torsional buckling (LTB), which led to the development of Eurocode 3 design rules accounting for the beneficial effect of non-uniform bending in laterally unrestrained beams. New calculation formulae for stainless steel beams under fire conditions have recently been proposed for incorporation in the second generation of Eurocode 3 − their safety evaluation in the context of different bending moment diagrams is still a relevant issue that needs to be investigated. This paper presents a numerical study on the resistance of stainless steel I-beams with slender and non-slender cross-sections and undergoing LTB when acted by end moments at elevated temperatures, focusing on the influence of the moment gradient. The safety and accuracy of the Eurocode 3 design approaches (current and second generation versions), as well as a design proposal previously developed for beams with stocky stainless steel sections, are assessed through the comparison of their predictions with extensive numerical failure moments obtained with the software ANSYS. It is shown that the design proposal previously developed for stainless steel beams with stocky sections provides the best predictions, even if having considerable number of underestimations.

Numerical Study on Upgrade of Steel I-Beams and Columns with Rectangular Web Openings

This study investigated numerically the effect of small and large rectangular web openings in unstrengthened and strengthened steel I-beams and columns. With the use of a numerical model, 25 simply supported steel I-beams were subjected to a four-point bending test. In addition, 25 steel I-columns were tested numerically under axial compressive load. All steel I-beams and columns were compared with solid reference specimens without web openings (control specimen), where all specimens have the same 400 mm depth and 177 mm width steel section dimensions. Twelve of the 25 steel I-beams and columns with openings were strengthened with steel plates, and all had different web openings that were symmetrically located near the support areas. The performance of all steel I-beams and columns was compared before and after a strengthening procedure. The selected opening depths ranged from 40 to 280 mm. Aspect ratios of opening length to opening depth of 1.0, 2.0, and 3.0 were chosen. ABAQUS software was used to perform numerical analysis on I-sections (beams and columns) that were either unstrengthened or strengthened. All specimens were analyzed in terms of their load-displacement characteristics and failure modes. Finite element analysis showed that those beams and columns with small web openings have a slight decrease in strength and stiffness, which is considered to be within acceptable limits unlike solid steel beams and columns (control specimen). I-section beams and columns that have been strengthened have significant effects on increasing the load-displacement characteristics.

A New Formula for Predicting Lateral Distortional Buckling Strength of I-Beams Subjected to Different Loading Conditions

Lateral distortional buckling (LDB) mode has been investigated as one of the failure modes in steel I-beams. The LDB mode in such beams is known by simultaneous lateral deflection, twist, and cross-sectional change due to web distortion. However, many studies have been conducted to investigate the behavior of this failure mode; so far, no formula has been found to calculate the ultimate LDB resistance of I-beams, which also takes into account the effect of different loading conditions. Consequently, in the current paper, by conducting an extensive parametric study, it was tried to investigate the effect of all main parameters as well as the effect of different loading conditions on the ultimate LDB resistance of I-shaped beams. Then, based on the provided database, the artificial neural network (ANN) method was employed, and based on it, a high-precision formulation was proposed to predict the ultimate LDB strength of steel I-beams. In addition to the ANN method, a regression-based formula was also developed as a classical method to examine the differences between the two methods. Finally, the proposed formulas were compared with other existing formulas for estimating the LDB strength. The results showed that the proposed formula based on ANN not only presents a reasonable accuracy compared to the existing formulations but also can be used by engineers as practical equations in the design of I-beams.

Assessment of lateral–torsional buckling in steel I-beams with sinusoidal web openings

Beams with sinusoidal web opening are alveolar beams manufactured from a single web cut, which lead to the production of higher I-sections and with a better strength-to-weight ratio when compared to the I-sections from which they originated. There are few studies in the literature about this I-section type, especially in relation to their behavior regarding global stability and Lateral Torsional Buckling (LTB) strength. Bearing in mind the importance of understanding the behavior of alveolar beams with sinusoidal openings in relation to LTB, an extensive parametric study was carried out through numerical analysis in the commercial finite element software ABAQUS. The study was performed with 10 I-sections of the IPE type, with lengths ranging from 6 m to 32 m. In addition, initial imperfections were considered, such as residual stresses and geometric imperfections. With the parametric study results, it was possible to evaluate the main existing analytical procedures, both for the determination of the LTB elastic critical moment, as well as the LTB ultimate moment. The adequacy of standard procedures (AISC; Eurocode 3 and AS4100) was evaluated, as well as analytical procedures present in the scientific literature for determining the LTB ultimate moment. Through the achieved results, it was possible to analyze the behavior of different adaptation methods for the calculation of the elastic critical moment in sinusoidal alveolar beams, as an alternative to the traditional double-T approach. Furthermore, it was found that the AISC-360 standard is unsafe in the case of actions applied to the upper flange, even though this is the most common condition in engineering projects.

Behavior of steel I-beams reinforced while under load

Steel I-beams often require reinforcing while they are under load. A common method for strengthening steel beams is by welding steel cover plates to the bottom flanges of the existing members. Very limited research has been conducted on the behavior of I-beams reinforced under load. This paper presents a finite element (FE) based study on steel I-beams welded with steel cover plates while under load. A series of simply supported steel I-beams reinforced with cover plates welded at the bottom flanges are analysed. FE analysis shows that with increased preload, the capacity of the I-beam reinforced under load reduces when the failure mode of the beam is lateral-torsional buckling (LTB). On the other hand, the variation of the preload has an insignificant effect on the behavior and ultimate strength of the reinforced beam when the reinforced beam fails in flexural yielding. Also, effects of different parameters, such as residual stress patterns in the I-beam and cover plate, welding residual stress, type of welding patterns, the difference in steel grades between I-beam and reinforcing plate, on the behavior of the steel I-beams reinforced while under load are investigated numerically. Finally, the flexural capacities of reinforced I-beams with welded cover plates obtained from FE analyses are compared with the capacities predicted by the American (AISC 360-16) and Canadian (CAN/CSA-S16-19) steel design standards. FE analysis shows that AISC 360-16, when the effect of loading height is considered, can reasonably predict the capacity of I-beam reinforced with welded cover plate at the bottom flange.

Testing Mechanical Stresses of Bearing Steel I-Beams of Automobile Overpass Using Magnetic and Tensometric Methods

Testing Mechanical Stresses of Bearing Steel I-Beams of Automobile Overpass Using Magnetic and Tensometric Methods

Effects of Shear on the Elastic Lateral Torsional Buckling of Doubly Symmetric I-Beams

The theoretical lateral-torsional buckling solutions for I-beams utilized in many design specifications may the overestimate lateral torsional buckling (LTB) resistance when significant shear is present due to web distortion. This paper investigates the effects of shear on the elastic LTB of doubly symmetric steel I-beams through computational models. A parametric study was conducted considering a range of geometric parameters and loading conditions commonly found in design applications in buildings and bridges. The results show that shear can have a substantial impact on the LTB resistance under many practical design circumstances. The impact of shear on LTB is more significant for sections with larger web slenderness ratios and smaller depth-to-flange width ratios. Postbuckling shear resistance does not significantly impact the reductions in LTB resistance due to shear. A practical design method that accounts for shear effects on the LTB behavior in stiffened and unstiffened beams was proposed and verified by comparison with computational solutions. Design examples demonstrating the proposed method are provided.

Performance Analysis of Castellated Steel I-Beam using FRP Stiffeners

Abstract: Castellated beams are now widely used for a variety of structural applications. Castellated beams are the ones which have perforations in their web part. However, these perforations increase stress concentration around the openings, and also get subjected to web post-buckling. To reduce these post-buckling failures and increase the load-carrying capacity, the castellated steel I-beams are provided with different types of stiffeners at various locations. In this paper, the behaviour of a hexagonal castellated steel I-beam (ISMB) under point loading is investigated using carbon fibre polymer (CFRP) strips as stiffeners. Two different types of CFRP strip stiffeners are provided in the transverse direction and around the openings of the castellated beam. The finite element analysis of these stiffeners has been carried out by using ABAQUS software. The results show that the use of CFRP stiffeners for castellated beams enhances load-carrying capacity up to 20% and reduces the deflection by 12% as compared to the control castellated beam. The use of transverse CFRP stiffener reduces the web buckling failure and increases the load carrying capacity effectively as compared to the stiffeners used along the openings. As a result, it is preferable to use transverse stiffeners instead of the stiffeners used along of the openings. Keywords: Abacus software, Castellated beam, CFRP, Openings, Transverse stiffeners