Flange Width Research Articles

Elastic and inelastic analyses of composite cellular beams in hogging moment regions

The present paper aims to assess the elastic and inelastic behavior of steel–concrete​ composite cellular beams in hogging moment regions. The finite element model is developed via ABAQUS software. In the parametric study, the unrestrained length, I-section dimensions, loading conditions, and the key parameters of the cellular beams are varied. The elastic results are compared with analytical procedures. From the elastic analysis, it was possible to observe interactions between lateral distortional and local buckling modes. The web-post buckling was observed in the finite element models with short unrestrained length since it was under considerable shear force. The flange width, flange thickness, web depth, and web thickness were the parameters that had the greatest influence on the elastic critical load. Some analytical procedures, such as AS 4100:1998, provided non-conservative results for the beams with lower I-section global slenderness and subjected to gradient hogging moment.

Dissipating the earthquake lateral base force of structure using sliding plate and link beam base isolation

Link beam and sliding plates is used to isolate structure against lateral base shear of the foundation due to earthquake forces, the link beam element made from steel wide flange act as a metallic damper, combined with sliding plates become as base isolation. Analysis with the Etabs program results in significant differences in internal moment, shear and axial forces between structures that using link beam base isolation and those without, as well as the results for drift and deformation of the structure. The first step of analysis is estimate the dimensions of the structural elements. Base on the loads of the structure, the lateral base force of the structure can be calculated manually, so that, by applying the dynamic balance equation, the size of steel wide flange that will be used as the link beam. can be found. Furthermore, the analysis of internal forces, deformation, and structural drifts are calculated using the Etabs program for structural systems that with or without base isolation. The both results are compared so that it can be concluded that by using the base isolation link beam there is a significant decrease in the magnitude of the internal forces, drift and displacement, so that by using this base isolation, the elements of the structure will be reduced significantly, and the cost of structure can be saved, the safety and comfort of the building can be further improved too.

Application of variable-height beams with wooden sub-rafter elements in the roof structures of industrial buildings

The investigation pertains to the coating utilized in single-story industrial buildings. Frame constructions with spans of 24, 30, and 36 meters are examined, employing wood-based elements as rafter structures. The reinforced concrete rafter structures exhibit a pitch of 2-3 meters and are configured in the shape of an I-beam. The truss structures along their length are subdivided into seven sections, featuring variable lengths, flange widths, rib thicknesses, and cross-section heights. Deflection calculations consider the nonlinearity of concrete and reinforcement deformations, adhering to prevailing building codes. The elastic solutions method is employed in conjunction with the finite difference method. The proposed coating designs are distinguished by their ease of manufacturing, transportation, and element installation. The wood-composite rafter structure boasts a lower mass compared to reinforced concrete elements, facilitating installation with a lightweight crane and overall diminishing the coating's weight without compromising its structural integrity. Several beam characteristics for spans of 24, 30, and 36 meters include respective mid-span heights of 1.2 meters, 1.4 meters, and 1.5 meters; volumes of 8.23 cubic meters, 9.25 cubic meters, and 10.6 cubic meters; and weights of 19.8 tons, 22.2 tons, and 25.4 tons. The proposed solution allows for the integration of bending moment and stiffness diagrams for the rafter beam configuration.

Investigating UHPC in deck bulb-tee girder connections, part 1: Analytical investigation

Precast concrete deck bulb-tee girder systems offer an excellent choice for prestressed concrete bridges with spans of 100 ft (30.48 m) or more. These girders are placed side by side in the field and connected using longitudinal joints. The wide top flange of the girders acts as a deck, eliminating the need for a cast-in-place concrete deck and providing a solution for accelerated bridge construction. However, the longitudinal joints between the girders often crack under service loads, allowing for water and deicing chemicals to enter the system and cause corrosion. An analytical study with ultra-high-performance concrete (UHPC) longitudinal joints was performed to investigate the joint performance when subjected to thermal and live loads. A continuity diaphragm with UHPC in the top flange was also investigated for negative moment over pier. Results of the investigation suggest that the use of UHPC can improve the performance of the connections. The high bond strength of the UHPC reduces the connection length and allows for simpler reinforcement details.

Experimental and numerical study on the shear lag behavior of l-shaped double-steel-plate composite shear wall

The shear lag behavior significantly affects the stress distribution of structural members, and ignorance of the shear lag behavior may cause serious engineering accidents. This work shows the shear lag behavior of two l-shaped double-steel-plate concrete composite shear wall (LDSCW) specimens (one with a wide flange and one with a narrow flange) under cyclic loading experimentally investigated. All specimens failed by the local buckling of the steel plate and concrete crushing. The LDSCW shows a good ability to dissipate energy, and the LDSCW with larger flange width exhibits better carrying capacity. The shear lag behavior is serious on the flange of the LDSCW. A finite-element (FE) model is developed to investigate the shear lag behavior of the LDSCW. It is concluded that the influences of the axial compression ratio and the height-width ratio of the flange of the LDSCW on the shear lag effect are significant. Models for predicting the effective flange width (EFW) of LDSCW in the Plastic Stage and Elastic Stage, which make good agreement with experimental results, are developed. The results of this work can provide a reference for the design of the LDSCW.

Confinement mechanism of FRP-confined concrete-encased cross-shaped steel columns

Fibre-reinforced polymer (FRP)-confined concrete-encased cross-shaped steel columns (FCCSCs) are an emerging type of hybrid columns. In an FCCSC, the concrete is subjected to combined confinement from the steel section and the FRP tube, leading to an enhanced load capacity and excellent ductility of the column. While several recent experimental studies have demonstrated the excellent structural performance of FCCSCs, the complex confinement mechanism behind their structural behaviour has not been clarified or thoroughly examined. This paper presents a comprehensive study aiming to investigate the confinement mechanism of FCCSCs. In this paper, the experimental observations of FCCSCs are first summarized, followed by three-dimensional FE modelling of the columns. The FE models, after being verified against the test results in various aspects, are used for a systematic parametric study. In this study, the complex interaction between the three components of FCCSCs (i.e., FRP tube, steel section and concrete) is illustrated explicitly and the effects of key parameters (i.e., flange width, flange thickness, web thickness and FRP tube thickness) are examined separately and thoroughly, leading to an in-depth understanding of the confinement mechanism of FCCSCs. In particular, through the examination on the distribution of steel flange-to-concrete normal pressure, it is shown quantitatively that the variations of the dimensions of the steel section in a practically wide range have only marginal effects on its confinement to the concrete, while the increase of FRP tube thickness tends to reduce the confinement effect from the steel section.

Simultaneous in-situ x-ray beam profile and intensity measurements with a minimally invasive pixelated diamond monitor

Measuring x-ray beam position, profile, and intensity at synchrotron beamlines provides valuable information for all experiments. Sydor’s transparent x-ray camera (TXC), based on technology originally developed at Brookhaven National Laboratory[1], enables these measurements in-line with experiments for live feedback. The TXC has a low beam profile that fits within a standard vacuum flange width and is composed of diamond material for > 90% transmission of > 5 keV x-rays, minimizing disruption of beamline space and the x-ray beam itself. Standard device parameters include 32 x 32, 60 µm pitch pixels, linearity over a 107 – 1016 photons/s dynamic imaging range, < 40 pA noise floor, and total flux measurement mode. Device performance has been evaluated using a pinhole mask with a benchtop silver x-ray tube and during beam focusing tests at the XFP beamline at NSLS-II and flux characterization at the FAST beamline at CHESS. This work will highlight the features of this commercial beam diagnostic, test results, and future directions and applications of the technology.

Thermal Gradients and Their Effects on Bending Behavior of Composite Girders with Trapezoidal Profiled Webs

Thermal gradient may have significant effect on the bending behavior of the composite girder with trapezoidal profiled web. To quantify such an effect on the thermos-strain action, temperature elevation test and finite element modeling were carried out on the specimens with the flange sensitive to bending and the web possessed adequate buckling resistance. The cross-sectional thermal gradients for different location away from the middle of span were measured using thermocouples and correlated using Boltzmann sigmoid equations. The applicability of finite element model was validated against experiments in terms of the distribution of thermal strain, deflections and axial strains. The axial strain distributions across the flange width and along the longitudinal direction of girder were analyzed in details. The testing and finite element modeling results showed that, the deflections with applied loads near the middle of span subjected to maximum bending moment are notably influenced by the increase of thermal gradient. The maximum axial strains at the upper surface and the lower surface of the bottom flange are obviously influenced by the temperature, especially for the girders with relatively high span-depth ratios or thicker flanges. The thermal gradient at the upper surface of the bottom flange is relatively higher than that on lower surface for every 10°C rise of temperature which meant that the upper surface of the bottom flange connecting trapezoidal profiled webs is more sensitive to thermo-elastic action.

Investigations on the influence of load width on web compression buckling strength of wide-flange steel members

A comprehensive study on web-compression buckling strength of wide-flange steel members subjected to concentric transverse loads spread over lengths longer than member section depth is presented in this paper. Calculation methodologies previously developed for web-compression-buckling strength of wide-flange steel members were established for use in beam-to-column moment connections, where the load width is relatively very narrow compared to the depth of the section, therefore does not include load width as a parameter in strength equations. More recently developed calculation procedures that account for load widths are typically limited to member section depth and are merely based on numerical models, and lack experimental evidence that validates these models. This study presents experimental research on steel wide-flange members subjected to transverse compression loading by having the load length as the primary variable. Experiments were conducted on specimens with measured imperfection levels and provided results on the buckling strength, displacement, and strain variation of the web portion during testing. The experimental program also investigated the potential of creep under sustained loading on web compression buckling strength of wide flange members at load levels near buckling strength. Benchmark numerical models using the finite element method were developed using the test results to obtain insights into the observed behavior and were employed in conducting numerical parametric studies to investigate the sensitivity of results due to load width and the angle of the applied load for various cross sections. The results obtained from the experimental and numerical studies were compared with the calculation methods provided in the North American and European design codes to evaluate their accuracy. The parametric study results were also used to develop an analytical calculation procedure for estimating the web-compression-buckling strength of steel wide-flange shapes subjected to vertical and inclined loading.

Experimental and numerical investigation of I-beam to concrete-filled tube (CFT) column moment connections with pipe-stiffened internal diaphragm

This paper presents an experimental and numerical investigation of two full-scale I-beam to concrete-filled tube (CFT) column internal-diaphragm moment connection specimens. In this type of connection, to allow the passage of concrete through the column tube wall, the internal diaphragms are perforated, which, as a result of drilling, creates stress concentration in these plates, reducing their strength and stiffness. In this study, first, to improve the diaphragms' performance, these plates were stiffened utilizing steel pipes, and the effect of this stiffening on the connection behavior under cyclic loading was investigated in the laboratory. In the second part, the specimens were analyzed by the finite element (FE) method in the Abaqus software. Results indicated that stiffening the internal diaphragm plates with the pipes increased the connection's flexural strength and cumulative energy dissipation by 20% and 22%, respectively. It also prevented the yielding of the diaphragm plates and increased the connection's stiffness by 8% to 22%. Furthermore, the stiffening of the internal diaphragms led to better stress distribution at the plastic hinge region in the beam and shifting of the maximum rupture index location from the outer edge of the beam flanges by about 40% of the beam flange width towards the beam's longitudinal axis. It was also concluded that the proposed connection with stiffened internal diaphragm meets the criteria for utilization in intermediate moment frames (IMFs) in seismic regions.

Application of a parallel laser apparatus to measure forearms and flanges of wild Bornean orangutans (Pongo pygmaeus wurmbii).

We constructed a parallel laser photogrammetry apparatus constructed from commercially available parts, and measured forearm lengths and flange widths of 16 wild Bornean orangutans. Our objectives were to validate our method and apparatus, discuss issues encountered, and construct preliminary growth curves. For adult males, we also compared flange width to forearm length as a way to investigate the relationship between body size and flange development. We used a camera cage around a DSLR camera, on top of which we attached two parallel green lasers. We estimated error with repeatability, accuracy, and interobserver reliability measures, and measured forearm lengths in three different ways to see which was most consistent. The longest forearm measure was the most repeatable (CV = 1.64%), and was similar to flange repeatability (3.50%). Accuracy measurements of a known object were high (error = 0.25%), and Interobserver discrepancy low (3.74%). Laser spacing increased with distance to the subject, but we corrected for this using calibration photos after each session. We transparently discuss the issues we encountered with the aim that this accessible method can help expand the use of laser photogrammetry. Preliminary measurements show that male flange widths and forearm length do not reliably increase in tandem, and that female growth plateaus at around the age at first birth (15 years old). We conclude with suggested improvements to the apparatus and method to ensure the lasers remain parallel.

Effects of biaxial loading path on seismic behavior of T-shaped RC walls

T-shaped RC walls are commonly used to resist horizontal seismic excitations in multiple directions. The differences in the intensity and spectrum characteristics of two translational components of ground motion cause the wall to experience complex biaxial displacement trajectories, resulting in a different seismic response compared to the behavior derived from conventional uniaxial cyclic tests. Thus, to investigate the seismic behavior and coupling mechanism of T-shaped walls subjected to different magnitudes of loading in two orthogonal directions, this study examined five identical T-shaped walls under uniaxial loading along two principal axes and biaxial loading with three represented loading paths. The test results showed that the mechanical behavior in one direction was significantly affected by the loading in the orthogonal direction owing to internal force redistribution and additional stress caused by the biaxial coupling bending, resulting in vertical variation and intersection of their hysteretic curves. Further, the biaxial loading primarily aggravated the cracking and damage of the flange, which accelerated the performance degradation in the flange direction and reduced the effective flange width involved in resisting web direction load. In addition, the biaxial coupling effect was found to be proportional to the area enclosed by the loading path. Thus, the most severe damage and performance degradation were observed under a square path, followed by an eight-shaped path, with the cruciform path exhibiting the least effect. Consequently, based on the results, recommendations for the design of T-shaped walls subjected to biaxial earthquake actions were proposed.

Evaluation of Laminated Composite Beam Theory Accuracy.

Carbon fiber-reinforced polymer (CFRP) has been widely implemented in electric vehicle bodies and aircraft fuselage structures. The purpose of CFRP is to reduce the weight and impart rigidity in the final product. A beam structure is typically used to bear the structural load, and the rigidity of the beam can be changed by arranging the laminated fibers at different angles. In this study, a composite I-beam is used as an example in engineering components. Because the theoretical model of the superimposed composite I-beam is established, the theoretical formula is based on the theoretical assumptions of the two-dimensional composite beam, and is combined with the traditional composite plate theory to analyze the maximum bending stress, strain, and deflection. During the theoretical derivation, it is assumed that the flanges of the I-beams are divided into narrow and wide flanges. The beams are considered as structures of beams and flatbeds. When a narrow flange is loaded in the side, the wide flange has no lateral deformation, and the lateral moments are neglected. Therefore, the accuracy of this formula needs to be verified. The purpose of this study is to verify the accuracy of theoretical solutions for the deflection and stress analysis of composite beams. A finite element analysis model is used as the basis for comparing the theoretical solutions. The results indicate that when the aspect ratio of the beam is >15, the theoretical solution will have better accuracy. Without the addition of the material, when 0° ply is placed on the outermost layer of the flange of the nonsymmetric beam, the effective rigidity of the beam is increased by 4–5% compared with the symmetrical beam. The accuracy range of the theoretical solution for the composite beams can be accurately defined based on the results of this study.

Best-fit constraint equations for coupling mixed-dimension simulation models with wide flange cross sections

A new mixed-dimension coupling method is formulated for members with (bi-symmetric) wide flange cross sections based on the idea of least squares transformations between two sets of point clouds. This coupling method imposes the minimum number of constraint equations required to link the displacement, rotation, and torsion-warping degrees-of-freedom of the dependent node. At the heart of the formulation is the solution of a 4 × 4 eigenvalue problem and the deduction of torsion-warping deformations. The proposed method is implemented and validated for nonlinear finite element analysis and the source code is made publicly available. Examples demonstrate that the proposed coupling method can improve interface stress distributions over alternative methods and is suitable for the coupling of elastic continuum finite elements. • A method to couple beam and continuum elements was developed using minimization. • The minimization implies a linear eigenproblem for bi-symmetric sections. • The method was implemented, then verified with numerical and experimental data. • The method results in minimal constraints to couple the beam and continuum domains. • Torsion-warping deformations are coupled, and shear stress transfer is improved.

Design and cyclic testing of bolted end plate connections between steel link beams and cross-laminated timber for coupled shear walls

Coupled cross-laminated timber (CLT) wall systems with ductile steel link beams offer an efficient, high-capacity lateral load resisting system for buildings in earthquake-prone regions. This study proposes a type of beam to CLT wall connection using a bolted end plate in a notched CLT panel edge to create a semi-rigid joint. A simplified analytical method is proposed to predict the connection strength and is compared against the results of full-scale experiments. The experimental strength values were all greater than the predictions from the proposed method. Therefore, the strength method seems conservative and is suitable for the capacity design of similar connections in coupled wall systems. The final specimen in the test programme was capacity designed and its cyclic test results demonstrated adequate connection strength and relatively high stiffness were achieved for a 200 mm-deep wide flange link beam. The specimen’s link beam yielded at an applied shear load of 180kN and reached a maximum strength of 278kN while dissipating a large amount of energy through steel yielding. The bolted end plate connection appears to be a practical solution for application in coupled CLT shear walls.

Axial compression behavior of core-steel tube with T-shaped flanges reinforced concrete column

A novel core-steel tube with T-shaped flanges reinforced concrete (CSTRC) column is proposed. The steel skeleton of CSTRC columns consists of a core-steel tube with T-shaped steel welded around the steel tube. Ten CSTRC column specimens and one contrast specimen without core-steel tube are tested to examine their axial compression behavior. The effects of the cross-section form of core-steel tubes, the steel flange width, steel flange thickness, steel web height, and volume ratio of stirrups on the failure mode and bearing capacity of CSTRC column are also methodically investigated. Furthermore, finite element models are developed to conduct parametric studies to determine how the strength of both the concrete and the steel skeleton affects the bearing capacity and ductility. Finally, a calculation formula to predict the axial compression bearing capacity of CSTRC columns is established. The test results reveal that: (1) compared with the contrast column, all CSTRC columns exhibit good bearing capacity, with a better deformation regime; (2) the cross-section form of core-steel tubes has little influence on the bearing capacity of CSTRC columns, but demonstrates great impact on its ductility. Additionally, growing the width and thickness of the steel shape flange and lessening the stirrup spacing enhances the ductility of CSTRC columns; (3) increasing the strength of both the concrete and the steel skeleton improves the bearing capacity of columns, but decreases the ductility; (4) the prediction results calculated by the proposed approach agree well with the experimental results, which confirms the suitable accuracy of the proposed method.

Seismic performance study on Q460 high-strength steel welded cruciform beam-column connections

Four Q460 high-strength steel welded cruciform beam-column connection specimens were designed. Among them, different forms of weld access holes were adopted for three specimens, and the locally expanded beam flange configuration was adopted for the other one. Quasi-static tests were carried out on the specimens. Seismic performance of the specimens was studied. The test results show that the specimens have good seismic performance. The ultimate failure modes of each specimen are all shown as the fracture of the beam flange steel base metal or welding material near the weld access hole. Ductility of high-strength steel welded connection can be improved by changing the form of weld access hole. Seismic performance of the expanded beam flange connection specimen was relatively better, which was mainly reflected in the fact that the failure at the weld access hole was delayed in late loading period. Finite element analysis (FEA) was conducted on each specimen. The FEA results were almost consistent with the test results. Analysis shows that the maximum von Mises stresses around the weld access holes of each specimen occurred near the weld access hole toes. The von Mises stress value of each specimen in the middle part of the beam flange width was almost the same. The difference of the von Mises stress values in the beam web height direction of the specimens with different configurations was mainly manifested in the range of three times of the weld access hole height below the upper weld access hole.

Residual Stresses in Welded I‐section Members with Flame‐cut Flanges

AbstractThe residual stress distribution influences substantially the stability behavior of steel members. Its shape, directly impacted by the fabrication process, is very different in hot‐rolled and welded members. Among welded members, flame‐cut flanges and hot‐rolled flanges are commonly employed in practice. However, buckling curves of Eurocode 3 are based on experimental tests and numerical simulations performed on welded members having hot‐rolled flanges only and lead to conservative results comparatively to the previous French design standards but also to hot‐rolled members. Investigations are strongly needed to adapt the existing buckling curves to welded members using flame‐cut flanges and a first step is to estimate the residual stress distribution in such members.The results available in the literature dealing with residual stresses measurements in welded members with flame‐cut flanges investigate stocky profiles that can be far from common practice, welded members being preferably slender sections. This paper presents the results of an experimental campaign on residual stresses performed on eight slender welded members varying the flange width and thickness as well as the flange type : hot‐rolled or flame‐cut. The measurements were performed using the sectioning method. A new model for residual stress distribution in welded I‐section members with flame‐cut flanges is then proposed based on these tests results and existing data from the literature.

Elastic Local Buckling Strength of Wide Flange Beams Web Subjected to End Moment and Distributed Load

AbstractThe buckling modes of wide flange beams are classified as lateral buckling and local buckling. AIJ Recommendations for Stability Design of Steel Structure [1] for these buckling modes are based on elastic buckling strength. It is therefore important to understand the elastic buckling strength and buckling modes of wide flange beams. The current design specifications make provisions based on simple stress states such as uniform compression and pure shear stress. For long‐span beams, which are currently used in many structural members, dead loads dominate in short‐term loading. However, few studies have considered stress changes due to distributed loading, and the specifications do not adequately consider actual design situations. The aim of this study is to determine the elastic local buckling strength of the web of wide flange beam subjected to uniformly distributed load and end moments. The subject is the web with 4 edge fixed support and the analysis method is a theoretical analysis using the energy method. By considering the difference between the maximum positions of bending stresses and shear stresses, the buckling strength and buckling mode could be correctly determined. The shear buckling coefficient enabled a unified classification of the buckling modes.

Cyclic behavior of metallic damper connected reinforced concrete beam-column joint with an opening in slab

The study proposes a solution of constructing the inevitable rectangular opening in the reinforced concrete (RC) slab upon the metallic damper for the RC beam-column frame to alleviate the adverse effect of the slab for the system compared to the designed bare frame joint. To systematically understand the cyclic behavior of the system, a quasi-static test is conducted on two half-scale specimens, and a parametric study is carried out to explore the effects of the rectangular opening of the RC slab along with the top and bottom flanges of the damper on the hysteretic responses of the system. Test results show that the positive and negative bearing capacities of the system are asymmetric because the centroid shifts upward from the middle of the metallic damper and RC beam. Although the intervention of opening in RC slab for the dog-bone damper connected RC joint is hard to mitigate the additional stiffness and bearing capacity from the slab to the system, such application could restrain the out-of-plane instability of the dog-bone damper by about 21.74% and improve both loading capacity degradation and energy dissipation degradation of the system. Furthermore, numerical results confirm that the distance of opening from the RC slab significantly decreases the depth of the neutral axis of the RC beam with the slab so that the bearing capacity and initial stiffness of the system improve by about 26.47% and 27.88%, respectively, as the distance of the opening to the damper reduced from 0 mm to 60 mm. Moreover, benefitting from the significant influence on the depth of the neutral axis, the bottom flange of the dog-bone damper, especially the flange width and weakened depth of the damper, has a significant improvement on the hysteretic responses of the system.