Steel I-beams Research Articles

Structural topology optimization for plastic-limit behavior of I-beams, considering various beam-column connections

This work proposes topology optimization for steel I-beams, including consideration of bolted beam-column connections with geometric and material nonlinear analysis. The aim is to assess and compare the topological configurations influenced by different connections, examining their stress distribution and rotational stiffness to illustrate the potential of structural optimization. The bi-directional evolutionary structural optimization (BESO) approach is implemented. Furthermore, several bolted steel beam-column configurations were validated based on experimental tests. Subsequently, a series of finite element models were developed, contributing to a comprehensive understanding of the plastic-limit behavior of I-beams under different loading conditions. The proposed method could potentially use a lesser quantity of material while maintaining the same level of structural performance. The results indicate that the implementation of structural topology optimization on I-beams while considering various beam-column connections, yields structural performance similar to that of solid web configurations, achieved through material reduction.

Using Machine Learning Algorithms to Develop a Predictive Model for Computing the Maximum Deflection of Horizontally Curved Steel I-Beams

Horizontally curved steel I-beams exhibit a complicated mechanical response as they experience a combination of bending, shear, and torsion, which varies based on the geometry of the beam at hand. The behaviour of these beams is therefore quite difficult to predict, as they can fail due to either flexure, shear, torsion, lateral torsional buckling, or a combination of these types of failure. This therefore necessitates the usage of complicated nonlinear analyses in order to accurately model their behaviour. Currently, little guidance is provided by international design standards in consideration of the serviceability limit states of horizontally curved steel I-beams. In this research, an experimentally validated dataset was created and was used to train numerous machine learning (ML) algorithms for predicting the midspan deflection at failure as well as the failure load of numerous horizontally curved steel I-beams. According to the experimental and numerical investigation, the deep artificial neural network model was found to be the most accurate when used to predict the validation dataset, where a mean absolute error of 6.4 mm (16.20%) was observed. This accuracy far surpassed that of Castigliano’s second theorem, where the mean absolute error was found to be equal to 49.84 mm (126%). The deep artificial neural network was also capable of estimating the failure load with a mean absolute error of 30.43 kN (22.42%). This predictive model, which is the first of its kind in the international literature, can be used by professional engineers for the design of curved steel I-beams since it is currently the most accurate model ever developed.

Optimization analysis for bolted steel I-beam: Considering various sizes of beam web with a focus on sustainability design

Abstract Steel structural construction has consistently held a pivotal role in modern construction practices. Presently, a substantial portion of research efforts has been directed towards the examination of bolted connections, while the optimization of steel beam usage has not garnered equivalent attention. This research initiative is focused on determining the ideal dimensions for the beam web through the utilization of finite element analysis (FEA). This analysis specifically investigates bolted steel I-beams featuring varying beam web sizes under concentrated loads. To achieve this, a three-dimensional (3D) simulation model of a bolted beam-to-column structure has been meticulously constructed and executed within the ABAQUS software to derive optimization insights. The beam web sizes considered span a range from 200 mm, representing a smaller size, to 400 mm, signifying a medium size, and up to 600 mm, which represents a larger beam web size. Following the simulation, the results pertaining to beam displacement and bending stress have been tabulated and compared against manually calculated values to validate the accuracy of the simulation. Remarkably, the percentage disparity between the FEA and manual calculations remained below 5 %, signifying a high level of acceptability. From the post hoc test, the efficiency rate of the 400 mm beam web size stood at 76.67 %, rendering it the most favourable choice in terms of cost-effectiveness and sustainability among the three considered sizes.

Stress-strain state of steel corrugated I-beams prestressed by flange drawing

The material distribution in structures is an urgent scientific and technical problem. Corrugated and prestressed steel structures are efficient and reliable.Purpose: The aim of this paper is to study the operation of steel I-beam with a thin corrugated wall, prestressed by flange drawing.Methodology/approach: Finite element modeling of beams with corrugated and flat walls (models with flat wall, transversely corrugated wall, downward corrugation at an angle of inclination 20 degrees, ascending corrugation at an angle of inclination 20 degrees). The proposed method is used for prestressing the lower beam flange using negative temperature effects. Numerical experiments in LIRA-SAPR software allow to obtain the stress distribution isofields and deformation patterns. A comparative analysis of the stress-strain state.Research findings: The normal stress distribution over flanges of corrugated beams with and without prestress under the external load has low difference. Prestress produces significant deflections of structures and the greatest deflection of the beam with ascending corrugations.

Reinforcing preloaded steel I-beams by considering welding heat effects and geometric imperfections

Steel I-beams are often strengthened by welding steel cover plates to the bottom flanges of the beams. However, very limited studies have been conducted on the effect of welding heat on the behaviour of I-beams reinforced while under load. This paper presents a finite element (FE) analysis-based study on the behaviour of preloaded steel I-beams reinforced with cover plates welded to the bottom flanges of beams, considering welding procedure simulation. FE analysis is conducted to study the effects of welding heat, welding sequence, and weld length on the residual welding deformation and behaviour of steel I-beams reinforced while under load. It is observed that an appropriate welding sequence and weld length can reduce the residual lateral deformations induced from welding of a reinforcing plate to the bottom flange of the preloaded I-beam and thus control the unfavourable welding effects. Based on the analyses, a welding segment length of L/9, where L is the length of the beam, is recommended for practical applications. In addition, FE analysis shows that the direction and magnitude of the initial geometrical imperfection can change the value and direction of the residual deformation resulting from welding. Furthermore, it is observed that preloading does not have any significant effect on the behaviour and ultimate capacity of the I-beam reinforced at a preload level up to 50% of the strength of the unreinforced beam. Also, when compared with the current standards AISC 360-16 and CSA S16-9, FE analysis of reinforced steel I-beams considering welding simulation shows that the current standards significantly overpredict the moment capacities of the reinforced beams when the top flange loading effect is not considered.

Behavior of Metal Frame of Ribbed-ring Dome with Decrease in Number of Supporting Columns

Investigation of the stress state of the metal frame of a ribbed-ring dome, when the number of supporting columns under it is gradually reduced. With that, the same distances or steps between the columns are maintained along the entire contour of the support ring. The main elements of the dome frame and columns are made of steel I-beams. Frames, the domes of which are supported by a different number of cyclically symmetrical columns, were considered as subjects of research. All the domes are characterized by the same geometric structure and size, the same cross sections of the same type of frame elements and are exposed to the same loads. The research was carried out on computer models by calculating the combined effect of the load from the weight of load-bearing and enclosing structures and an asymmetric snow load. The models with a reduced number of columns are obtained by regularly removing them from the original computer model. During the analysis, the stresses in the elements of the frames of all models were determined, which were compared with each other. Deformation graphs and comparative diagrams of the stress state relationships of the frame elements of the original and transformed models are obtained. An assessment of the change in the stress state of the ribbed-ring dome frame with a decrease in the number of columns is given. Significant changes in the stress state of the support ring were noted.

Lateral torsional capacity of steel beams in different loading conditions by neural network

Lateral torsional buckling (LTB) is a common mode of failure in steel structures due to instability. However, current standard recommendations have limitations in accurately determining the ultimate capacity of members subjected to LTB. To address this issue, an in-depth parametric study using finite-element analysis (FEA) was conducted to investigate the effects of major parameters, including various types of loading, on the strength of steel I-beams. Additionally, the artificial neural network (ANN) technique was used to find a reliable procedure for assessing the LTB strength of steel I-beams using a generated database. To demonstrate the efficacy of the developed formulation, it was compared against predictions using existing equations. The presented formula demonstrated strong accuracy, making it an effective tool for engineers designing I-beams to resist LTB. This research makes significant contributions to the structural engineering field and has important implications for the creation and evaluation of steel structures.

Experiments on fire-protected and hot-dip galvanised steel bolted connections

Connections are of high significance in the stability and integrity of steel structures. Connections play a key role in structures exposed to fire because they are supposed to support the entire elements against a variety of loads. In steel beams, a connection is generally implemented to join (at least) two perpendicular members. A thorough understanding of the heat transfer in structural members is a prerequisite to a reliable design. In the case of R30 requirements, a large number of members can be left unprotected if they are hot-dip galvanised. If hot-dip galvanising of a structure is not sufficient to provide required fire resistance, one part of the structure could be hot-dip galvanised while another part to be protected with a reactive fire protection system. When connecting a protected beam to an unprotected hot-dip galvanised beam, information regarding the heat transfer between these beams is required.Additional heating in a connection due to hot dip galvanisation needs to be taken into account when verifying the load-bearing capacity of the component protected by reactive fire protection according to EN 1993-1-2. This study investigates the effect of heat development and transfer in full-scale steel I-beams from a hot-dip galvanised secondary beam to an intumescent-coated main beam through various bolted connections such as fin plates, double angles, and stiffeners with lugs. Fire protection was applied to the main beams, while the secondary beams were hot-dip galvanised. A thorough experimental, numerical and theoretical study was implemented as presented in this paper, the results of which are deemed to provide significant input into improving safety, hence mitigating the risk of steel beams.

Tensile strength analysis of sandwich composite-to-metal joints based on experimental investigation and progressive failure method

In this study, the tensile strength characteristics of the hybrid sandwich composite-to-metal specimen consisting of two steel I-beams and a T-shaped sandwich composite structure were studied. The tensile strength of the sandwich hybrid joints under design load and ultimate load has been tested. The progressive failure model is established according to the modified Shokrieh-Hashin criterion. The interface cohesive zone model is applied to reveal the damage development of the bonding layer. The stresses, strains, ultimate strength, and main damage modes of the hybrid joint under design load and ultimate load conditions are simulated and the predicted results are compared with those from tests. The experimental and numerical results show that the strain, the trend of load-displacement curves and the damage modes are in good agreement. The strength of matrix is the main factor limiting ultimate strength. Therefore, the influences of the overlapping width and thickness on ultimate bearing capacity were analyzed to obtain the optimized structural strength of the sandwich composite-to-metal bolted joints.

Plastic-limit probabilistic structural topology optimization of steel beams

This work presents a novel geometrically nonlinear analysis with imperfections reliability-based topology optimization (RBTO) approach, considering the volume fraction and geometric imperfections as random variables due to their crucial connections to the manufacturability of web openings in steel I-beams. The objective is achieved by controlling the plastic behavior through limit analysis, which imposes a limit on the plastic ultimate load multipliers. The suggested method is developed by imposing constraints related to the available material volume. The bi-directional evolutionary structural optimization (BESO) method is utilized to fulfill the objectives of this paper. The adequacy of the proposed technique is demonstrated by comparing the results of the algorithm with benchmark steel beams that have conventional web openings. Based on the numerical examples, it appears that the selected technique has the potential to increase the load capacity of steel beams while utilizing the same quantity of material within the design domain. Moreover, the improved beams also exhibit better performance in terms of stress levels. The results of this research suggest that the proposed technique enhances the load capacity of steel beams while maintaining the same quantity of material and improving their performance in terms of stress levels.

ЭЛЕМЕНТЫ ОЦЕНКИ РЕСУРСА СТАЛЬНЫХ БАЛОК, ПРЕДВАРИТЕЛЬНО НАПРЯЖЕННЫХ ВЫТЯЖКОЙ СТЕНКИ

The article presents possible ways to determine service life of steel single-span beams with prestressed web. The authors implement the method for searching coefficients of optimal distribution of material over the cross section of a symmetrical, monometallic steel I-beam. Basing on structures theory the study determines the maximum permissible moments of external loads for ordinary and prestressed beams. It formulates analytical expressions characterizing the first and second limit states of prestressed beams and establishes the resource of their bearing capacity. As a result of performed analysis, analytical dependences of prestressed beams stiffness are determined and structures resource is established according to this criterion. The study determines height of beams and its change with span variations and actual uniformly distributed load. Resource height of prestressed beams is established in comparison with height of conventional bending structures. Load-bearing capacity of beams with prestressed web is 1,8 times higher than the corresponding capacity of conventional beam and their resource is 180 %. Deflections of prestressed beams are 77,3 % less than deflections of traditional beams and stiffness resource is 1,29. Height of conventional beam is 1,847 times higher than height of prestressed structure. Service life of prestressed beam is 187%. Key words: prestressing, optimal design, load-bearing capacity, rigidity, service life.

ПОСТРОЕНИЕ УПРУГОЙ ЛИНИИ БАЛКИ И ОПРЕДЕЛЕНИЕ ВЕЛИЧИНЫ И НАПРАВЛЕНИЯ ГЛАВНЫХ НАПРЯЖЕНИЙ В СЕЧЕНИИ БАЛКИ

The paper uses the data from diagrams of I-beam transverse forces and bending moments to calculate the values and directions of primary stresses at three points of the beam cross-section – on the neutral axis, above and below it. To calculate the values of primary stresses, the graphic analytical method with the construction of Mohr's circles is used. Further, the article presents an algorithm for constructing a beam deflection line and calculating cross-section deflections. To determine deflections, the universal beam deflection line equation is used. After determining the largest deflection value, conclusion is made that the hardness condition of a steel I-beam is met.

GPS-Based Network Synchronization of Wireless Sensors for Extracting Propagation of Disturbance on Structural Systems.

Wireless sensor networks (WSNs) have gained a positive popularity for structural health monitoring (SHM) applications. The underlying reason for using WSNs is the vast number of devices supporting wireless networks available these days. However, some of these devices are expensive. The main objective of this paper is to develop a cost-effective WSN based on low power consumption and long-range radios, which can perform real-time, real-scale acceleration data analyses. Since a detection system for vibration propagation is proposed in this paper, the synchronized monitoring of acceleration data is necessary. To meet this need, a Pulse Per Second (PPS) synchronization method is proposed with the help of GPS (Global Positioning System) receivers, representing an addition to the synchronization method based on real-time clock (RTC). As a result, RTC+PPS is the term used when referring to this method in this paper. In summary, the experiments presented in this research consist in performing specific and synchronized measurements on a full-scale steel I-beam. Finally, it is possible to perform measurements with a synchronization success of 100% in a total of 30 samples, thereby obtaining the propagation of vibrations in the structure under consideration by implementing the RTS+PPS method.

Influence of the size of the upper ring on the stressed state of the ribbed-ring metal dome

Studies of several metal ribbed-ring large-span domes on computer models have been carried out. All elements of the dome frames are made of steel I-beams. The dome frames have the same number of ribs and rings, but they have different size of the upper ring. The frame elements cross-sections are oriented normally to the dome surfaces, with the exception of the upper ring. The joints of the frame elements with each other are assumed to be rigid in the normal direction and hinged in the tangential direction. The frames are mounted on support nodes at the level of the lower ring pivotally. All the domes are subjected to the same nodal loads from the weight of the enclosing structures and the weight of snow. The snow load is assumed to be asymmetrical, located only on one side of the dome. Under the combined action of these loads, the dimensions of the upper ring of the domes influence the stress-strain state of their frames. As a result of the research, graphs have been generated representing the stress level in the meridional ribs and in the upper rings of the domes. The conclusion has been made that the stress state of metal dome frames depends on the size of the upper ring. The necessity of increasing the cross-section of the upper ring with an increase in its size has been noted.

Study of Damping of Bare and Encased Steel I-Beams Using the Thermoelastic Model

Steel I-beams are a fundamental structural component in civil construction. They are one of the main load-bearing components in a building that must withstand both the structure and any incoming external perturbations, such as seismic events. To avoid damage to the structure, the building must be designed to dissipate the maximum amount of energy possible. One way energy can be dissipated is through internal or structural damping, of which thermoelasticity is one of the causes, especially in low-frequency harmonic excitations. The main goal of this study is to analyze the amount of damping in an I-beam generated by thermoelasticity and when encased in a Portland cement concrete layer, using a Finite Element model. It was found that, due to the geometry of the I-Beam, the damping coefficient as a function of frequency has two local maxima, as opposed to the traditional single maximum in rectangular beams. Encasing an I-beam in a concrete layer decreases the overall damping. While the extra coating protects the beam, the reduction in damping leads to a lower energy dissipation rate and higher vibration amplitudes.

Flexural Behavior of Rectangular Double Hollow Flange Cold-Formed Steel I-beam

This research experimentally investigates the flexural behavior of rectangular hollow flange cold-formed steel I-beam (RHFCFSIB) under two concentrated loads at the same distance from the support. All specimens were at a constant clear span of (L=1500mm), a constant beam specifications (t=4mm) web, flange thickness (h=300mm) for beam′s depth, and flange width of (bf=150mm). The connecting distance between the bolts, i.e., connects the web to the flanges, was (L/6), and eight stiffeners for each beam were placed under the load bearing points and at the support points on each side. The experimental program included assembling the parts to make beams and testing four specimens under two-point loads. The major parameters adopted in the current research included the flange depth, i.e., hf=30,60,90, and 120mm. The results showed that the beam with a flange depth of 30 mm had a higher ultimate load than other beams; however, it was the highest beam deflection. The beam with a flange depth of 120mm was the best section as a flexural member. The ultimate capacity of this beam increased by 15.34% and 6.4% compared to beams with flange depths of 60mm and 90mm and decreased by 12.9% compared to a beam with a flange depth of 30 mm. The maximum deflection at beam mid-span with a flange depth of 120 mm decreased by 53.8%, 44%, and 19.94% compared to beams with flange depths of 30 mm, 60mm, and 90mm, respectively. Therefore, the flange depth significantly influenced the flexural behavior by increasing the flange depth. Also, the ultimate capacity increased, and the deflection was reduced. The main conclusions drawn from the study were discussed and summarized. The research showed that the Hollow flanged sections gave the best results for flexural behavior.

Machine learning approach for predicting bridge components’ condition ratings

Information on bridge condition rating is critical to make decisions regarding rehabilitation or replacement of bridges. Currently, bridge components’ condition ratings are evaluated manually using inspection reports. Markov chain and Petri net models are most commonly used for predicting future values of bridge parameters, however, applicability of these models for a regional or statewide portfolio of bridges may be limited. The existing data based models have low prediction accuracy. Hence, a data and machine learning based approach is presented herein for predicting the future condition values of major components—deck, superstructure and substructure—in a portfolio of bridges with an objective to develop a more accurate approach. National Bridge Inventory (NBI) was used to get information on current and past bridge components’ condition from year 1992–2019 along with other parameters such as ownership, maintenance responsibility and age. After selecting important parameters, this data was used to train three RUSBoost based random forest models for predicting future values of deck, superstructure, and substructure conditions, respectively. The prediction accuracy of the developed models were found above 93%, thereby addressing the limitation of poor prediction accuracy of the existing studies. Additionally, the uncertainties associated with the random forest based predictions were quantified at the regional level and for individual bridges. On-system concrete pre-cast slab units and steel I-beam bridges in Louisiana were selected to demonstrate the proposed approach and predict bridge components condition ratings for years 2020 and 2021.

Behavior of unrestrained hot-rolled steel I-beams exposed to localized fire: An experimental study

The behaviour of hot-rolled steel I-section beams was studied experimentally and numerically in uniform temperatures in the past, but only limited experimental data are available for localized fire tests. The present paper reports ten experimental tests for short to medium-range laterally unrestrained I-beams of Class 1 section with a non-dimensional slenderness ratio in the range of 0.74 to 1.1. The localized fire behaviour of unrestrained I-beams is experimentally studied with a high thermal zone having a temperature range of 595 to 1200 °C. Three-point loading is provided considering simply-supported boundary conditions with pre-load and peak load (ultimate load) in the range of 0.26 to 0.76 of the design load capacity of a beam member at ambient temperature. The two types of fire scenarios are considered (a) fire concentration at the middle of the span and (b) fire concentration near the support of the beam under steady and transient experimental conditions. The geometrical imperfection is measured using an industrial blue-light optical scanner. A numerical validation study was also conducted using the robust FE modelling software ABAQUS. The experimental study concluded that failure mode can depend on fire location, load ratios, and span length. In the case of localized fire at the middle of the span, lateral torsional buckling happened, and when the fire was near support, local buckling happened at higher load ratios. However, local buckling happened in the beam for lower to mid-load ratios. It is observed that the steady and transient fire tests provided a negligible effect on the response of the beam member. The experimental and numerical results are in good agreement, with a mean percentage variation of 1.5 %, with a maximum value of up to 4.67 %. The study provides quite a simple experimental setup that can easily be replicated for different types of members that enhance the fire safety study of structure. Further, a parametric study is conducted under simply-supported and varying end restraints condition at supports.

Nonlinear Inelastic Stability Behavior of High-Strength Stainless Steel I-Beams with Sinusoidal Web Openings

Perforated beams can bring countless benefits compared to traditional plain-webbed beams. However, steel beams with sequential web openings are more susceptible to instabilities, and special care must be taken in a design concerning the failure modes these structures can present. The study presented herein explicitly dealt with the stability behavior of perforated beams with sinusoidal openings. This type of perforated member features smooth-lined openings constructed from a single thermal cut in conventional plain-webbed steel profiles. A broad study was carried out through numerical simulation using the ABAQUS software, in which perforated profiles manufactured with S600E high-strength stainless steel were studied. The use of high-strength steels in perforated profiles is a little explored topic in the literature, despite having a significant impact on the behavior of these elements. With the study carried out, a broad overview of the stability behavior of these members was obtained, especially concerning global stability. A total of 5940 FE models were developed, considering the application of different types of loads. In these models, linear buckling analysis (LBA) and geometrically and materially nonlinear analysis with imperfections (GMNIA) were performed. The results obtained were compared with international design codes, and it was found that some codes fail to represent the behavior of members that present lateral-distortional buckling (LDB) and interactions between local and global failure modes. This behavior is a significant design concern since the studied members had high yield strength, making them more susceptible to interaction-governed failure modes than usual-yield strength members. Additionally, the study found that some design codes do not accurately represent the behavior of members loaded outside the shear center due to the destabilizing effect of loading on these structures.

Field Investigation of the Reinforcement and Support Mechanism for a Tunnel in Layered Soft Rock Mass

A crucial deformation phenomenon is observed in shale and silty clay sections in a tunnel. To analyse the reinforcement and support mechanism and behaviour of the tunnel support structure in layered soft rocks, field tests for the axial force of the cartridge rock bolt, surrounding rock pressure, stress of a steel I-beam and lattice girder were performed. Based on the field deformation analysis data, the reinforcement behaviours of the cartridge rock bolt and steel floral pipe, and support behaviours of lattice girder and steel I-beam in the layered rock mass and silty clay were analysed.