Flange Width Research Articles

New design model for the slab reinforcement in external steel-concrete composite joints under sagging moment

Concrete and structural steel are the two most widely used materials in composite construction. Although the behaviour of composite joints' under hogging moment is well covered, it must be recognized that the behaviour of these joints under positive moment bending effect -sagging moment- is not yet been fully mastered. Such loading condition might arise in constructions composites joints exposed to seismic events. This paper aims to presented in this paper is devoted to characterize the behaviour of single-sided composite joints under sagging moments and provide a design approach to estimate the required reinforcement in the vicinity of the composite joint. The European code Eurocode 8 (Code, 2005b), which is concerned with seismic action, provides an analytical formula to assess the reinforcement under mechanism 1 only. However, no formula is provided to estimate the reinforcement under mechanism 2, although the entire reinforcement section is obtained under the effects both resisting mechanisms. The influences of the investigated parameters, namely the column height, column flange width, and slab width are highlighted. These parameters play a significant role in determining the amount of transverse reinforcement and the activation of resisting mechanisms 1 and 2 in the slab. The transverse reinforcement rate, needed to prevent yielding, is estimated under the combination of mechanism 1 using the analytical formula from the European code Eurocode 8 (Code, 2005b), and under mechanism 2 using the proposed analytical model. The last is validated by comparing it to the numerical simulation results of VecTor2. Adequate convergence has been achieved through the proposed model.

Numerical study of the effect of circular openings in the upper surface of rectangular hollow flange steel beams on the sectional moment capacity

Rectangular Hollow Flange (RHF) steel beams may have openings drilled in their top surface to pass some plumbing and electrical wiring inside the RHF cavity. These openings affect the behavior of these steel beams and may reduce their resistance to bending moment. To investigate this effect, Finite Element Modeling (FEM) was used to simulate RHF steel beams with and without flange openings with several variables in geometric dimensions. The FEM results were examined using 8 experimental test specimens of RHF steel beams obtained from previous studies without flange openings. The results showed high accuracy in modeling these RHF steel beams in structural behavior and ultimate bending moment capacity. Current design codes were applied to predict the capacity of these RHF steel beams without flange openings, both from FEM results and experimental tests. The prediction values were always less than the ultimate capacity of RHF steel beams without flange openings. After verifying the results, 98 RHF steel beams with different flange opening diameters were modeled. The reduction ratios in ultimate capacity in steel beams with hollow flange openings are directly proportional to the opening diameter, hollow flange height, and steel yield stress, while they are inversely proportional to the thickness and width of the hollow flange and the steel beam web height. The reduction ratios in the ultimate capacity for RHF steel beams with flange openings are small in the compact category, and these ratios increase with the non-compact and slender categories.

Shear behavior of FRP-UHPC composite beams enhanced by FRP shear key: Experimental study and theoretical analysis

To investigate the shear behavior of FRP (fiber reinforced polymers)-UHPC (ultra-high performance concrete) composite beams, four-point bending tests were conducted on seven FRP-UHPC specimens and two FRP-NSC (normal strength concrete) specimens, having different width and depth of concrete flange as well as FRP shear key (FSK) spacing. The slip between FRP profiles and concrete flange was controlled by employing FSK and epoxy resin bonded hybrid connection. The failure pattern, load-deflection/strain curves, and sliding response of composite beams were analyzed to study the influence of concrete type, FSK spacing, width and thickness of concrete slab. The results indicate that FRP-UHPC composite beams exhibited shear failure, while FRP-NSC composite beams experienced bending-shear failure. The composite beams demonstrated shear-lag effect, which became more pronounced with the increasing of the concrete slab width. The use of UHPC, reducing FSK spacing, and increasing the size of cross-section of concrete flange can effectively enhance the shear performance and reduce interface sliding. Formulae were developed to predict the shear capacity and deflection, considering shear deformation. The results predicted by the formulae developed match well with the experimental results.

Structural Retrofitting of Corrosion-Damaged Columns in Reinforced Concrete Buildings : A Case Study in KFC Commercial Restaurant Banda Aceh, Indonesia

Abstract The aim of this paper is to identify effective strategies and solution for damaged column due to corrosion. It investigates a case study of a commercial building in Aceh Province, Indonesia, that suffered from corrosion attack in its columns. The building’s structural deterioration was due to the corrosion of its embedded steel reinforcement, which led to cracking, spalling of concrete and ultimately local buckling. The assessment method that conducted on the existing building involved a combination of non-destructive testing, visual inspections, and laboratory analysis to assess the structural condition and identifying the necessary repairs. The structural model was developed using finite element analysis software, which utilizes a numerical method to simulate the structural response to different loads. The retrofitting strategy included both jacketing and the addition of wide flange profile columns to enhance structural integrity. It demonstrates the effectiveness of structural retrofitting in restoring the integrity of structural column damaged by corrosion with the retrofitted columns exhibiting up to 15 greater strength than the existing column. This study provides insights into effective strategies for rehabilitating structures affected by natural disasters.

Online pre-perception of forming state based on real-time measurement in spinning of thin-walled shell component

Die-less spinning is an advance incremental forming process widely used for the manufacturing of thin-walled shell components. During the spinning, workpiece shape and forming state both change continuously, and the influence of process parameters on the forming results is also time-varying, which make it difficult to control the forming quality. To this end, this work develops a real-time measurement system and an online pre-perception method to provide technical support for dynamic control of the spinning process. Specifically, the real-time measurement system is constructed firstly by placing two laser profilers bilaterally at two sides of the workpiece. Based on the measuring data of two laser profilers, the profile data of workpiece cross-section is obtained by coordinate transformation, data denoising and correcting the error caused by inclined workpiece surface. Then, an algorithm is proposed to identify the critical geometric parameters (flange width, roller action radius, wall thickness and flange fluctuation degree) of workpiece shape from the profile data. In contrast to the measurement results by a three-coordinate measuring machine, the developed system presents a real-time measurement error less than 4 %. Moreover, an online pre-perception method of wall thickness and wrinkling defect is developed based on the real-time measured workpiece shape parameters. The online pre-perception of wall thickness and wrinkling defect presents high accuracy with the relative error less than 2.1 %. The above results indicate both the workpiece dimensions and spinning state can be well real-time measured and online pre-perceived, which can provide important foundation for the study of time-varying influence and dynamic control of the spinning process.

Prediction of crippling load of I-shaped steel columns by using soft computing techniques

This study is primarily aimed at creating three machine learning models: artificial neural network (ANN), random forest (RF), and k-nearest neighbour (KNN), so as to predict the crippling load (CL) of I-shaped steel columns. Five input parameters, namely length of column (L), width of flange (bf), flange thickness (tf), web thickness (tw) and height of column (H), are used to compute the crippling load (CL). A range of performance indicators, including the coefficient of determination (R2), variance account factor (VAF), a-10 index, root mean square error (RMSE), mean absolute error (MAE) and mean absolute deviation (MAD), are used to assess the effectiveness of the established machine learning models. The results show that all of the three ML (machine learning) models can accurately predict the crippling load, but the performance of ANN is superior: it delivers the highest value of R2 = 0.998 and the lowest value of RMSE = 0.008 in the training phase, as well as the highest value of R2 = 0.996 and the smaller value of RMSE = 0.012 in the testing phase. Additional methods, including rank analysis, reliability analysis, regression plot, Taylor diagram and error matrix plot, are employed to assess the models’ performance. The reliability index (β) of the models is calculated by using the first-order second moment (FOSM) technique, and the result is compared with the actual value. Additionally, sensitivity analysis is performed to check the impact of the input variables on the output (CL), finding that bf has the greatest impact on the crippling load, followed by tf, tw, H and L, in that order. This study demonstrates that ML techniques are useful for developing a reliable numerical tool for measuring the crippling load of I-shaped steel columns. It is found that the proposed techniques can also be used to predict other kinds of failures as well as different kinds of perforated columns.

Flexural behavior of cold-formed steel I-beams strengthened in the web with different materials

This research presents an experimental and theoretical study investigating the flexural capacity of built-up steel cold-formed I-beams strengthened in the hollow web with different materials. Eight built-up cold-formed steel I-beams were prepared and experimentally tested. As a control specimen, one was not strengthened, steel shear connectors strengthened one without materials, and six specimens were strengthened by filling the hollow web with different materials. The strengthened materials used are wood wastes (Sawdust with epoxy- Sawdust with polyester), lightweight concrete, normal-weight concrete, High-Strength concrete, and polymer mortar. The specimens' method of failure, load at failure, and vertical displacements were recorded. The relationship between vertical load and deflection at the span's midpoint has been graphed to analyze the impact of strengthened materials. Using polymer mortar resulted in the highest capacity, outperforming other materials. Finite element models of the tested beams were established. Good agreements between experimental and numerical models were observed. 84-FE numerical models were established to determine the effect of cover plate thickness on flange width ratios and the height-to-width of the strengthening material. Finally, new equations that calculate strengthened beam capacity were presented.

Analysis of Factors Affecting the Seismic Performance of Widened Flange Connections in Mid-Flange H-Beams and Box Columns

Following the Northridge and Kobe earthquakes, research has increasingly focused on achieving high ductility in beam-to-column connections. This study investigates the seismic performance of connections featuring widened beam-end flanges in mid-flange H-beams and box columns, an area with limited prior research compared to I-section columns and narrow-flange H-beams. Detailed finite element modeling using ABAQUS 6.1.4 demonstrates that widened beam-end flanges significantly improve bending capacity and ductility by relocating the plastic hinge away from the connection, thereby enhancing seismic resilience. Key findings include the identification of optimal design parameters: flange length ranging from 0.55 to 0.75 times the beam flange width, beam flange cutting length between 0.36 and 0.39 times the beam depth, and flange cutting depth from 0.19 to 0.23 times the beam flange width. These parameters ensure effective plastic hinge development and improved structural performance. This study introduces a novel approach that emphasizes geometric optimization over material-based enhancements, offering a cost-effective and practical solution for improving seismic performance and extending previous research insights.

Hysteretic behavior of eccentric RHS beam-to-column joints under cyclic in-plane bending

This paper conducted experimental and numerical studies on the hysteretic behavior of eccentric rectangular hollow section (RHS) beam-to-column joints under cyclic in-plane bending. The study began with the design of both stiffened and unstiffened joints, followed by hysteresis tests that revealed failure modes like web weld tearing and stiffener fracture. The seismic performance of the joints was evaluated using hysteresis curves, skeleton curves, ductility coefficients, strength degradation coefficients, and energy dissipation coefficients. Compared to unstiffened joints, the stiffened joints exhibited a 30 % increase in peak load and a 18 % improvement in maximum energy dissipation coefficient. Subsequently, finite element (FE) analysis was performed, and the influence of key parameters on the hysteretic behavior was studied using validated FE models. The results indicated that the hysteretic behavior was positively correlated with the flange width ratio of beam to column, the ratio of beam section height to column flange width, and the thickness ratio of beam to column, while it was negatively correlated with the width-to-thickness ratio of the column. Finally, a mathematical model for the hysteretic behavior of both stiffened and unstiffened joints was developed and validated through experimental and FE comparison, offering practical applicability in engineering design.

Heat transfer mechanism of superabsorbent polymers phase change energy storage cold-formed steel wall under fire

The superabsorbent polymer phase change materials (SAP materials) exhibit exceptional water absorption and retention properties, offering substantial potential for fire protection in steel structures, thereby reducing the need for sheathing boards and fire-retardant coatings, while minimizing energy consumption. Understanding the heat-mass exchange theory of SAP materials is crucial for enhancing their application in the building industry. This study develops a comprehensive theoretical model for heat-mass exchange in cold-formed steel (CFS) walls incorporating SAP materials. An equilibrium phase change model and a simplified thermal radiation model were developed to capture the water loss and dynamic heat exchange processes in SAP materials. These models were integrated into a transient fluid-solid-thermal coupling model using Ansys Fluent and User Defined Functions. In the case study, the newly developed numerical models can accurately predict temperature field changes in CFS walls with SAP materials, demonstrating the heat transfer mechanisms of hot and cold flanges at different temperature rise stages. The developed numerical model was used to investigate the effects of factors such as the moisture content of the SAP material, web depth, and flange width on the fire resistance of the CFS wall. Results indicated that increasing the wall stud height improves fire resistance, while increasing flange width has little effect on hot flange temperature. These findings provide a theoretical foundation and practical guidelines for the application of SAP phase change insulation materials in the building industry, promoting energy reduction and supporting sustainable construction practices.

Investigations On the Effective Width of Wide Flange Steel Girders

AbstractEffective width, as presented in Eurocode 3 is analysed. Efforts have been made to distinguish between the behaviour of the various structural parts acting as wide flanges. Different mechanical models are adopted: for the bridge deck plate between girders, for the cantilever deck part, and for the bottom plate of box girders with the presumption to reflect more adequately their actual participation in the complex girder work at bending. Also, the interaction between girders in a superstructure at loading is simulated as far as possible in order to replace to some extent a sophisticated spatial analysis. The Eurocode 3 way of presenting the matter is preserved. The results obtained are compared with the corresponding Eurocode parts and an assessment on the reported differences is given. The goal is to supply the designers with extended understanding the effects arising from the shear lag phenomenon.

Simplified Direct Strength Method for the design of cold-formed steel channels with circular web openings under two-flange loadings

Previous studies have put forward reduction factor equations to determine the web crippling strength of cold-formed steel (CFS) channels with circular web openings. However, these equations overlook vital parameters such as material yield strength, flange width, and fillet radius of CFS channels. Consequently, this paper introduces simplified Direct Strength Method (DSM) equations, which account for plastic loads (Py) and elastic buckling loads (Pcr), integrating the aforementioned crucial parameters. Eight unique yield line models were devised, considering two-flange loadings: interior-two-flange (ITF) and end-two-flange (ETF), as well as the positioning of circular web openings, to compute the yield line length for Py. Similarly, new Pcr equations were also proposed. The reliability of the proposed equations was evaluated using a dataset of 236 test results sourced from the literature. This assessment aims to demonstrate the suitability of the equations for incorporation into future revisions of international design codes.

Numerical analysis of the seismic performance of existing steel frames with rigid connection with truss-beam-segments

Addressing the insufficient research on fully welded connection with truss-beam-segments (FWCT), this study conducts a comprehensive investigation into the seismic performance of FWCT and its associated steel frame. Primary parameters influencing the seismic performance of FWCT are examined through numerical analysis, and a design method for FWCT is provided. Subsequently, a time-history analysis of composite frames with FWCTs is proposed to investigate the effect of adding truss-beam-segments during rare earthquakes on the seismic performance of the structure as a whole, along with reinforcement recommendations. The study results show that the width of the truss-beam-segment (TS) should ideally be equal to the width of the beam flange, with a thickness equal to that of the beam flange. The net height should be less than or equal to 0.17 times the clear height of the steel beam. The horizontal angle of the external diagonal leg should be less than or equal to 40°, and the length of the horizontal short leg should be greater than the plastic deformation region length at the beam root. The axial compression ratio for the column should be less than 0.7 to prevent local buckling of the column. As the thickness of the composite slab increases, the initial stiffness and load-bearing capacity of the positive moment region gradually increase, while those of the negative moment region remain relatively constant. Time-history analysis indicates that the maximum story displacement and inter-story displacement of the composite frame with TSs are reduced by 4.7 %–5.3 % and 2.5 %–5.8 %, respectively, compared to the composite frame without TSs under seismic wave action. This implies an enhanced capacity of the composite frame with TSs to withstand lateral deformation. For a mid-to high-rise composite frame with n stories, the addition of TSs was recommended primarily for the first (n/2 + 1) floors where plastic regions occur, aiming for a more economically efficient retrofit design and enhanced seismic performance.

Withdrawal Capacity of a Novel Rigging Device for Prefabricated Wood I-Joist Floor Panels

Prefabricated wood construction relies heavily on efficient material handling, yet rigging system design for floor panels remains understudied. This study introduces a novel rigging device that attaches to prefabricated wood I-joist floor panels using self-tapping screws, avoiding potential damage caused by predrilled holes in the sheathing panels and framing members. To establish allowable lifting capacities and optimal installation practices, comprehensive withdrawal tests were conducted on 114-floor panel specimens. Factors influencing withdrawal capacity, such as anchor plate placements, flange materials and width, screw type and quantity, and sheathing panel thickness, were systematically evaluated. Results indicate that withdrawal capacity does not scale linearly with screw quantity and that anchor plates with eight screws centered on the flange enhance performance by up to 20% compared to four-screw configurations. Unexpectedly, thinner sheathing panels yielded higher capacities, potentially due to increased screw penetration depth in the joist flange. In addition, anchor plate orientation, flange width, and flange materials also impact capacity. These findings provide essential data for designing reliable and efficient rigging systems in prefabricated wood construction.

Destructive Testing of the Pinkabach Railway Bridge – Large scale Testing of Sensor Systems for Fatigue Crack Monitoring and System Identification

The work presents experiments carried out on an out-of-service steel railway bridge, the so called Pinkabach bridge. The objective was to test advanced and novel sensor systems, i.e. Distributed Fiber Optic Sensing (DFOS) and Acoustic Emission (AE), for the monitoring of fatigue cracks, both for crack initiation and subsequent crack growth, in steel railway bridges. Also, sensor systems for overall system identification, i.e. Tiny Motion (TM), Distributed Acoustic Sensing (DAS) and dynamic response analysis, have been tested. The Pinkabach bridge was a single span plate girder railway bridge with a span width of 21,5m that was taken out of service and transported to a secure environment that allowed for destructive testing with permanent access to the structure itself under controlled conditions. By harmonic excitation of the structure at its first resonance frequency, cyclic stress levels comparable to the stress levels during train passage were generated and it was possible to emulate the fatigue load from decades of train traffic within the limited period of the experiments. Crack initiation and growth happened at two locations of the flanges and crack growth was monitored till the crack length was half of the flange width of the main girder. To end the experiments a static load test showed the remaining capacity of the damaged structure. A conventional sensor system was used for validation and comparison with calculated predictions based on linear fracture mechanics, used for the design of the experiments. An overview over the whole set of experiments as well as (intermediate) results and findings on the applicability of the novel sensor systems are presented in this paper. The experiments are a collaborative work of multiple scientific and industrial partners and have been carried out as part of Area 3.1 of the COMET Project Rail4Future, funded by the Austrian Research Promotion Agency FFG.

Serviceability limit state of incrementally launched steel bridge I-girders

Bridge girders are subjected to repeated patch loading during incremental launching (i.e. travelling over supports). Plastic deformations are likely to occur in the girder already at the first patch loading. They influence the girder’s structural response and bring about a decrease in the ultimate resistance at subsequent patch loadings. This problem is analysed in the present paper through the serviceability limit state (SLS) of incrementally launched bridge I-girders (ILBGs). The SLS of ILBGs is a current problem since only a few studies, with contrasting conclusions and certain limitations, have been recognised in the literature. Research is limited on plate girders without longitudinal stiffeners made of structural steel. Flat slide-type launching shoes are considered in this paper.The serviceability requirement (repeatable behaviour of ILBGs) and criterion (that effective membrane strains should remain in the elastic range) are adopted from the literature. So, the serviceability resistance is adopted as a load at the start of the effective membrane plastic strains in the girder. In order to propose a practical and simple SLS design procedure, the serviceability resistance is normalised against the ultimate resistance, so a serviceability correction factor (ksls) is defined. The paper presents a parametric numerical analysis of the factor (ksls). A finite element model previously developed and validated by the author is employed to simulate a nonlinear response of patch-loaded girders. The parametric study includes 599 girders. ksls is inversely proportional to the web thickness and directly proportional to the flange thickness and the yield strength of the steel material. The load length, web depth and flange width do not influence ksls. The influence of the spacing between transverse stiffeners on ksls is negligible. Finally, by regression analysis of the results of parametric study, an original and reliable serviceability correction factor is proposed as the main objective of the research. The range when the SLS of ILBGs should be checked is also defined.

Experimental Study on Shear Lag Effect of Long-Span Wide Prestressed Concrete Cable-Stayed Bridge Box Girder under Eccentric Load

Based on the engineering background of the wide-width single cable-stayed bridge, the shear lag effects of the cross-section of these bridge box girders under the action of the eccentric load were experimentally studied. The behavior of shear lag effects in the horizontal and longitudinal bridge directions under eccentric load in the operational stage of a single cable-stayed bridge was analyzed by a model testing method and a finite element (FE) analytical method. The results showed that the plane stress calculation under unidirectional live load was similar to the results from spatial FE analysis and structural calculations performed according to the effective flange width described in the design specification. At the position of the main beam near the cable force point of action, the positive stress at its upper wing edge was greatest. At a distance from the cable tension point, the maximum positive stress position trend showed that from the center of the top flange to the junction of the top flange and the middle web to the junction of the top flange and the middle web and the side web. Under eccentric load, the positive and negative shear lag effects on the end fulcrum existed at the same time, and the shear lag coefficient on the web plate was larger than the shear lag coefficient on the unforced side. Due to the influence of constraint at the middle fulcrum near the middle pivot point, positive and negative shear lag effects were significant, and the coefficient variation range was large, resulting in large tensile stress on the roof plate in this area. According to FE analytical results, stress and shear forces of a single box three-chamber box girder under eccentric load were theoretically analyzed, the bending load decomposed into the accumulation of bending moment and axial force, using the bar simulation method, and the overall shear lag effect coefficient λ was obtained and verified.

Off-label use of Lumen-apposing metal stents for treatment of short benign biliary strictures

BackgroundEndoscopic stenting is the mainstay of treatment for benign biliary strictures. There is a not-negligible rate of recurrence and stent migration. Lumen-apposing metal stents (LAMS) have a unique design with short length, large diameter and wide flanges which make them less prone to migration. AimsTo describe the intraluminal use of LAMS to treat short benign biliary strictures. MethodsAll consecutive patients who underwent bi-flanged LAMS placement for benign biliary strictures, in approximately 6 years, were retrospectively included. Primary outcomes were technical and clinical success; secondary outcomes were number of endoscopic procedures, adverse events evaluation and stricture recurrence during follow-up. ResultsSeventy patients (35 male, mean age 67) were enrolled; bilio-enteric anastomotic stricture was the most common etiology. Technical and clinical success were 100 % and 85.7 %, respectively. Patients with post-surgical stricture had a higher success rate than patients with non-surgical stricture or with bilio-enteric anastomotic stricture (90.4 %, 86.3 % and 81.4 %, respectively). Adverse events were 12/70 (17.1 %): stent migration was the most frequent (8/70, 11.4 %). Stricture recurrence was found in 10/54 patients (18.5 %). ConclusionLAMS placement could be safe and effective treatment for short benign biliary strictures in patients in which a significant caliber disproportion between stricture and the duct above was revealed.

Process design for flexible T-profile-rolling of tailored thickness stringers with different cross sections

A new process, called flexible T-profile-rolling, is being developed to produce T-profiles with variable thickness distribution in longitudinal direction by flexible rolling. These tailored thicknesses allow for load-adapted and weight-optimised design of stringer profiles for aircrafts. The new process can replace the chemical milling currently used in the production of stringers and enables a more environmentally friendly and resource-saving production of the thickness changes. In order to achieve uniform thicknesses in the web and flange of the T-profile, a new rolling stand with rolls inclined against the T-profile and varying roll radii was developed. However, the varying roll radii cause different longitudinal strains in the profile cross-section due to the varied contact areas between the roll and the rolling stock, resulting in unwanted profile bowing. This bowing depends on the profile dimensions, as the adjacent roll radii vary over the profile cross-sections.This paper demonstrates the effects of profile dimensions on deflection through numerical investigations with different web heights, flange widths and thickness reductions. A straightening method is presented to obtain straight profiles as a function of the profile dimensions. The results show that this process can produce almost straight T-profiles with variable thicknesses for different cross section dimensions.

Structural Behavior Castellated 2C Cold-Formed Steel Beams

This study's primary objective is to examine the structural behavior of using 2C-Cold produced. Section Castellated beams when subjected to monotonic load till failure. The experimental program testing. Seven Fabricated samples of castellated steel beams and one sample, which is a non-castellated steel beam (reference beam), were tested as supported beams under concentrated loads at two points over a clear span length (1730 mm). All castellated steel beams were similar in all properties and dimensions except the breadth of the upper and lower flanges. The current study considers the implications of modifying the width of the top and bottom flanges on how these beams behave. The findings showed that the ratio of the tested Castellated beams' ultimate load-carrying capacity to the non-castellated reference beam (R1) ranged from 99.3 to 117.2%, and the ratio of the tested beams' ultimate deflection to the same reference beam (R1) ranged from 72.6 to 103.2%. Increasing the breadth of the top and bottom flanges has a direct relationship with castellated beam stiffness and ultimate load. Finally, adjusting the flange width between the top and bottom flanges reduces castellated beam rigidity and ultimate load.