Flange Width Research Articles

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.

АВТОМАТИЗОВАНЕ ПРОЄКТУВАННЯ ЛОНЖЕРОНУ КРИЛА БЕЗПІЛОТНОГО ПОВІТРЯНОГО СУДНА

One of the most crucial objective in designing aircraft structures is to ensure their strength while meeting the requirement for minimal weight. In operation, the structure must withstand loads without failure, as well as be designed with the lowest possible weight and, in most cases, volume.The determined geometric model of the structure based on the minimum weight criteria, reduces the overall weight of the aircraft which leads to: reducing the power requirements of the engine, and thus the cost of the aircraft; decreasing fuel consumption, making the aircraft cheaper in operation.The weight of the wing is equal 30-50% of the aircraft empty weight. Depending on the structural and load-carrying scheme of the wing, the weight of the spars can range 7-30% of the wing`s weight. Wing spar geometric model determination has a significant impact on the weight of the aircraft and thus on its cost and operational expenses.The problems of the wing spar automated design of an unmanned aerial vehicle are considered. The concept of creating a wing spar of an unmanned aerial vehicle according to the minimum mass criterion is presented.This study determines relation between the minimum required volume (weight) of the wing spar and the number of stiffeners as well as relations between the cross-section geometric properties of the spar (thicknesses of the flanges and web, flanges width) along its span.This study proposes approach for determining geometrical model of the wing spar based on the minimum weight criteria, which can serve as a valuable reference for the design process of spars or similar beam elements. The determined geometrical model of the wing spar for unmanned aerial vehicle, derived from analogous aircrafts data, is applicable for preliminary design purposes in this class of aircraft.

Research on Anchorage Performance of the Foundation Ring for Wind Turbines.

The foundation ring (FR) is a steel component embedded within the concrete of a wind turbine foundation, playing a pivotal role in connecting the wind turbine tower to the foundation structure. In this paper, the FR-foundation connection is equivalent to the exposed foundation and the shallow foundation by analyzing the anchorage characteristics of the foundation ring. Based on the ABAQUS concrete damaged plasticity model, full-scale modeling of the wind turbine foundation is carried out. The influence of embedment depth, ring radius and base flange width of the foundation ring on moment capacity is simulated. Based on the observed stress distributions under ultimate loads, analytical expressions were proposed to estimate the variation law of anchorage load-bearing capacity in the ultimate load state. Compared with the numerical simulation, the average errors under different influencing factors are 8.2%, 9.6% and 10.8%, respectively. The results indicate that the base flange provided the majority of the moment capacity, though the contribution of the sidewall increased to 25-50% that of the base flange in later stages.

Experimental study on fatigue behavior of prefabricated high-strength steel-concrete composite bridge beams

To investigate the fatigue performance of prefabricated high-strength steel-concrete composite beams (P-HS-CCB), six specimens were designed with different fatigue load amplitudes, different fatigue load upper limits, and varying degrees of shear connection. Among them, specimen S560 underwent static failure testing, while the remaining five specimens underwent fatigue testing. The analysis was conducted from the perspectives of fatigue failure modes, fatigue life, and stiffness after specific cycles, with a comparison of the fatigue life calculation formula from different international codes. The results demonstrate that the fatigue failure mode of the P-HS-CCB is cracking in the vicinity of the steel beam at the mid-span, followed by crack propagation along both the web and flange widths. The P-HS-CBB exhibits excellent combination effects and anti-fatigue performance, maintaining nearly constant stiffness during fatigue loading with minimal composite section slip. The fatigue life of the P-HS-CBB is mainly influenced by the fatigue load amplitude during the testing. The S-N curve provided by AASHTO shows a good fit with the curve fitting based on experimental data and can be used to guide the anti-fatigue design of this type of beam.

On the Use of the Effective Width for Simply Supported Generally Loaded Box-Girders

A new method for evaluating the effective flange width of simply supported rectangular box-girders in bending is illustrated. It aims to overcome the lack in the literature of a general method able to supply the effective flange width for a general distribution of loads along the beam axis, not restricted, i.e., to the few cases reported in standard codes. The method consists of finding an analytical expression for the effective width under sinusoidal loads of arbitrary wavelength and combining the results in the framework of a Fourier analysis. The model allows investigating the shear-lag effects on displacements and stresses. The analytical formulation proposed is validated against numerical results supplied by refined Finite Element analyses.

A new resistance insert spot welding method for injection-molded FRP–steel component

For weight reduction, multi-material designs comprising metal and fiber-reinforced plastic (FRP) components in vehicle body structures have been increasingly used. However, the commonly used resistance spot welding (RSW) technology for car body assembly cannot be employed to join sheet metal and FRPs, limiting the use of FRPs. To solve this problem, a novel resistance insert spot welding (RISW) technique was developed in this work for RSW of steel parts and FRP structure parts made by injection molding. Small inserts were developed by using finite element method and experiments that may be welded to different micro-alloyed and dual-phase sheet steels using the projection welding method. The usual flange width of original equipment manufacturers could be kept unchanged. Using the developed insert and welding parameters, the maximum temperature in the FRPs surrounding the inserts was limited to 255 °C, minimizing the damage to polyamide 6 (PA6) material (with 40 wt% glass fiber). A weldability range between 2.5 and 7 kA could be achieved. The joining strength of RISW between a micro-alloyed HC340 steel in 0.75 mm and 1.5 mm thickness and a 2.5 mm/3.0 mm PA6-GF40 material is 20 to 80% higher than self-piercing riveting (SPR). For high-speed loading, RISW strength increases by 39 to 56% further. Finally, RISW was successfully applied to an FRP–steel roof-frame sub-assembly that consists of 19 simultaneously integrated inserts, achieving 10% weight reduction.

Experimental study on the flexural behavior of partially encased composite beams with corrugated steel webs

Combining the advantages of partially encased composite structure (PEC) and corrugated steel web, a new type of composite PEC beam with corrugated web was proposed in this paper, namely corrugated webbed PEC (CWPEC) beam. In order to investigate the structural performance of the proposed CWPEC beams, four specimens were designed and fabricated. Four-point bending tests were carried out to study their flexural performance and failure modes. The failure process, load-displacement curve and strain distribution of the tested specimens were analyzed. Experimental results showed the high load carrying capacity and superior ductility of the proposed concept. Parametric study indicated that the concrete strength was increased from C30 to C50, the ultimate load slightly increased by 3.38%. The flange strength decreased from Q355 B to Q235, the ultimate load reduced by 9.17%. The flange width decreased from 250 mm to 200 mm, the ultimate load decreased by 22.21%. As comparison, the increase of steel flange width is more efficient to improve section moment capacity. Further analysis verified that the flexural strength of CWPEC beam was mostly provided by flanges with little contribution from the corrugated web. Finally, based on the quasi-plane assumption, prediction formulas for cracking moment and ultimate moment of CWPEC beams were proposed.

Shear strength of prestressed concrete beams with short shear span: Full‐scale experiments and evaluation of design methods

AbstractPrestressed concrete (PC) is increasingly used in civil engineering construction. Notably, research on shear resistance in PC beams with short shear span remains relatively limited, necessitating further comprehensive exploration. In the study, tests were conducted on bonded post‐tensioned PC T‐beams with short shear span (a/h = 1.0), subjecting them to monotonic loading destructive tests. These beams measured 24.9 m in length, 1.605 m in height, and had a top flange width of 2.0 m. They featured a uniform cross‐section with a 0.22 m web thickness. Given the size of the full‐scale test beams and space constraints for loading, an innovative loading scheme was devised to minimize the counterweight. Test results demonstrate the safety and feasibility of the loading scheme. The tests were conducted five times and the main test variables were the draped tendons and the quantity of horizontal web reinforcement. The tests revealed that horizontal web reinforcement significantly influenced crack propagation but had a minimal effect on shear strength. For the parameter values taken for the test beams, the prestressing level has less effect on the shear strength of the beam. Simultaneously, an investigation was conducted involving a total of 119 PC beams. This investigation aimed to evaluate the degree of conservatism and accuracy in shear design code provisions and shear strength equations derived from various standards, including the strut‐and‐tie model (STM) of ACI, AASHTO, and Tan, as well as the critical crack model of Yuan and the truss model of Laskar. Comparative analysis indicates that, the design method provided by Yuan exhibit relatively superior predictive capabilities.