Gusset Plate Thickness Research Articles

Fatigue performance of a steel truss web-concrete external joint in railway composite continuous girder bridges

ABSTRACT This study conducted fatigue tests on two 1:3 steel truss web-concrete external joints to investigate their fatigue performance. The fatigue failure mode of the external joints and the stress distribution of each component were investigated. In addition, a finite element analysis (FEA) model was established, and parametric analysis was carried out to discuss the influence of gusset plate thickness, stiffening plate layout, and gusset plate structural form on fatigue performance. The results show that the fatigue life of the external joints under the design load amplitude is 3.75 million times (187.5 years). Fatigue cracks appear in the junction area between the gusset plate and the end of the stiffening plate, which is a weak fatigue detail of the external joint. The fatigue cracks cause local stress redistribution of the gusset plate. The stress at the junction (GN3) between the gusset plate and the stiffening plate N3 can be reduced by up to 37%, 61%, and 21% by altering the above three factors. Furthermore, the fatigue life of the optimized joint is increased by 1.4 times, indicating that the fatigue performance can be significantly enhanced by improving the stiffening plate layout and the gusset plate structural form.

Post-earthquake fire performance of the gusset plate moment connection

PurposeIn this paper, the seismic behavior of the gusset plate moment connection (GPMC) exposed to the post-earthquake fire (PEF) is investigated.Design/methodology/approachFor this purpose, for the sake of verification, first, a numerical model is built using ABAQUS software and then exposed to earthquakes and high temperatures. Afterward, the effects of a series of parameters, such as gusset plate thickness, gap width, steel grade, vertical load value and presence of the stiffeners, are evaluated on the behavior of the connection in the PEF conditions.FindingsBased on the results obtained from the parametric study, all parameters effectively played a role against the seismic loads, although, when exposed to fire, it was found that the vertical load value and presence of the stiffener revealed a great contribution and the other parameters could not significantly affect the connection performance. Finally, to develop the modeling and further study the performance of the connection, the 4 and 8-story frames are subjected to 11 accelerograms and 3 different fire scenarios. The findings demonstrate that high temperatures impose rotations on the structure, such that the story drifts were changed compared to the post-earthquake drift values.Originality/valueThe obtained results can be used by engineers to design the GPMC for the combined action of earthquake and fire.

Experimental and numerical studies of impact loading on single-layer reticulated shells with aluminium alloy gusset joints

Aluminium alloy materials have found extensive application in large-span space grid structures. While research on the mechanical properties of aluminium alloy materials and components is generally well-established, there remains an incomplete understanding of the overall structure. Therefore, further investigation into the overall performance of aluminium alloy reticulated shells is crucial to promote their use in spatial structures, guiding structural design and addressing practical engineering challenges. This study focuses on the design of a single-layer aluminium alloy reticulated shell with a 2 m span, which was subjected to an impact test to examine its dynamic response and failure mode. By comparing and analysing stress, acceleration, and displacement time-history curves obtained from these different test conditions, the dynamic response behavior of the reticulated shell was determined. To simulate the impact on reticulated shells, explicit dynamic analysis was conducted using non-linear finite element software LS-DYNA. Based on the deformation characteristics and failure phenomena observed during the impact test, three distinct failure modes were defined for the single-layer reticulated shell. Through parameter analysis using the validated finite element model, it was determined that increasing the thickness (tp) of the aluminium alloy gusset plate or reducing the radius (R) of the gusset plate effectively enhances the overall stiffness and impact resistance of the single-layer reticulated shell. Overall, this research contributes to a deeper understanding of the performance of aluminium alloy reticulated shells under impact loads. The findings provide valuable insights for guiding structural design and addressing practical engineering problems in the field of spatial structures.

Investigating seismic behaviour of cold-formed steel moment frames with the welded through-plate flexural connection

The Cold-Formed Steel (CFS) construction in seismic regions requires carefully selecting and designing an approved seismic-force resisting system. Among the available seismically-resistant structural systems, the bolted CFS moment frames have recently gained some attention. However, given the currently existing design issues associated with the bolted connections in CFS moment frames, this paper seeks to conduct a numerical investigation into the potential substitution of bolt fasteners with the weld materials in CFS frames. The objective is to explore the possibility of including the welded connection as an alternative to bolted connections in subsequent editions of the ASCE 7 code. To this end, finite element models, consisting of two built-up CFS beams and twenty-three flare-bevel-groove and fillet weld specimens, are initially validated against the cyclically and monotonically loaded tests with data available in the relevant literature. Subsequently, the verified weld and CFS beam models are incorporated in the simulation of thirty-four CFS beam-to-column welded moment connections, each differing in beam dimension, weld length and size, and gusset plate thickness. The built-up beams comprise back-to-back and lip-to-lip double C-section profiles. Stress variations along the weld lines, derived initially from nonlinear finite element analyses and then computed from the theoretical elastic analysis, are compared to establish a basis for categorizing stress distribution patterns in the longitudinal welds. Finally, six CFS frames assembled with the welded moment connection and subjected to a combined column axial compression and cyclic lateral drift are examined, resulting in an estimated seismic modification coefficient, R, equal to 3.8. Overall, the welded moment connections demonstrate a stable seismic response with an average ductility ratio, μ, of 2.7. The dominant failure mode is a locally developed ductile fracture in the two end segments of the longitudinal welds, identified as critical regions.

Experimental investigation of screwed beam-column connection using cold-formed steel back-to-back sections with gusset-plate

Fifteen tests have reported the experimental behavior of steel beam-column connections using cold-formed steel (CFS) sections with gusset plates attached to self-drilling screws. Using screws instead of bolts can be economical in cold-formed steel structures due to the nonexisting failure of bolts in tests. The aim of the study was to understand how gusset plate thickness, beam thickness, and stiffener use could affect screwed beam-column connections using cold-formed steel section behavior; experimental research using cantilever testing was carried out with full-scale specimens of the connections. The results presented here show which stiffeners can prevent the beam from collapsing at the gusset plate's end-point, but they cannot affect the failure modes. However, the stiffening cannot modify the failure mode; it does not affect the behavior and characteristic values of the moment-rotation curve. Additionally, the moment resistance significantly decreased in the beam thicknesses without stiffeners to less than 1.5 mm. Furthermore, the ductility of the joint with the thicknesses of the gusset plate (P) is 1.5 mm, and the C/P ratio (C is beam thickness) is less than 1, which decreased with the used stiffener in the test specimens. Thus, the gusset plate, beam thickness, and C/P ratio are essential in determining the failure mode shape and the moment resistance value. Additionally, the results presented here are compared with the literature.

An experimental study of FRP truss side plate joint

Ultra-high performance concrete (UHPC) slab - fiber reinforced polymer (FRP) truss hybrid beam has been proved as an effective and advanced bridge system. However, the limited shear strength and the significantly lower transverse properties compared with its longitudinal counterparts result in low rigidity and load carrying capacity of bolted FRP truss joints, which governs the overall performance of the UHPC slab- FRP truss hybrid beam. A FRP truss side plate joint was proposed which integrates a steel U-shaped gusset plate (SUGP) to reinforce the traditional bolted joint. The proposed joint outperformed the conventional bolted joints in terms of the failure mode, load carrying capacity, and stiffness. The load carrying capacity of the proposed joint can be improved by up to 63% and the ultimate deflection was reduced by up to 33%. The effects of a variety of key design parameters, including adhesive, bolt diameter, pre-torque, and length and thickness of the gusset plate, on the performance of the SUGP joint were evaluated. Test results showed that: (i) the adhesive between the pultruded FRP profiles and the steel gusset plate could increase both the initial stiffness and ultimate load carrying capacity of the steel SUGP joint; (ii) length and thickness of the steel gusset plate did not result in notable difference in the behavior of the steel SUGP joint for the range of parameters investigated herein; and (iii) application of pre-tightening torque within the thread of the bolts slightly improved the load carrying capacity but significantly improved the ductility of the steel SUGP joint.

Static performance of steel temcor joints subjected to axial tension and compression loads

In this study, steel temcor joints with Huck bolts (10.9 grade) for single-layer grid-shell structures were investigated. Experimental, numerical, and theoretical methods were adopted to explore the behaviour of the temcor joint of steel under axial tension and compression loads. In the beginning, six specimens with a single Huck bolt were designed to investigate the failure mode and the shear strength of the Huck bolt. And then, steel temcor joints (TC1, TC2, and TC3) were designed and tested considering the number of Huck bolts and the gusset plate thickness. In the test, the TC1 joint with only eight Huck bolts exhibited the lowest load-bearing capacity with main bolt shear failure under tension and compression loads. Moreover, the TC2 and TC3 joints exhibited higher bearing capacities with bolt shear failure in the tension tests, while they generated the same compressive bearing capacities with the main failure occurring in the H-shaped beam. A 1/6 FE models for three types of specimens in the tension and compression tests were established using Abaqus software. Simultaneously, a parametric analysis was conducted to explore the impact of the gusset plate thickness on the performance of steel temcor joints. The tension and compression theoretical solutions were derived. Finally, the steel temcor joint with Huck bolt exhibited excellent stiffness and bearing capacity which can satisfy the design requirements for the single-layer grid shell structures.

Assessment of frame corner connections subjected to cyclic loading in cold formed steel sections

This research investigates the performance of cold-formed steel moment connections subjected to quasi-static cyclic loading through laboratory testing and numerical modeling. The beam-to-column connections studied in this research were categorized into two types: screw-fastened connections and bolted connections. Three specimens were tested under cyclic loading, two of which were fastened using 6 mm self-drilling screws, and one specimen using 12 mm ordinary bolts. Numerical models were developed using finite element software and validated against the tested specimens. The finite element software was integrated with a user element subroutine verified previously in literature to capture the screw behavior accurately when subjected to cyclic loading. The verified numerical model was then used to develop a parametric study, where the effects of changing the gusset plate thickness, bolts/screws arrangement, and stiffeners' locations were investigated. The study showed that screw-fastened connections are capable of dissipating energy through ductile deformation under cyclic loading. Moreover, additional stiffening plate connecting the column's flanges with the beam's flanges improved the moment capacity significantly (35–41%), and energy dissipation capacity of the connection (26–28%).

FINITE ELEMENT ANALYSIS OF GUSSET PLATE CONNECTION DESIGN FOR COLD-FORMED STEEL FRAMES

The application of cold-formed steel sections has been extended from secondary members to primary structural members in recent years. This increases the use of gusset plate connections in cold-formed steel since it is a common connection used in steel structures. However, current design codes on connection design do not have a comprehensive method to consider the effects due to the buckling of the thin cold-formed steel sections. Therefore, it is important to develop a more accurate model to predict the capacity of cold-formed steel connections. This paper aims to propose an equation for gusset plate beam-to-column connection using finite element models. Finite element models have been developed and compared with existing test results. The failure mode and ultimate strength of the numerical models are similar to the experimental results. The validated finite element models are then used to study the effects of gusset plate thickness, effects of cold-formed steel section depth and thickness, and the effects of bolt size and spacings. Elastic and plastic stiffnesses are obtained from the developed models. The connection behavior followed a typical elastic-plastic curve according to the connection ductility and failure mode. An empirical model is developed from the finite element models to predict the joint behavior of gusset plate beam-to-column connection for cold-formed steel structures. AS 4600 may have underestimated the initial stiffness of the connection.

Static performance of steel temcor joint subjected to out-of-plane bending moments

The temcor system is one of the most famous single-layer grid shell structures’ connections. In this study, temcor joints were designed using Q345 steel with Huck bolts instead of the aluminium alloy to expand using an H-shaped beam of steel in single-layer grid shell structures. Twenty-two joints with a single Huck bolt connection were designed and tested to investigate the shear strength of Huck bolts. At the same time, three specimens of steel temcor joint (TC1, TC2, and TC3) were designed considering the number of Huck bolts, the thickness of the gusset plates, and material type. FE models for tested joints were established using Abaqus to conduct numerical and parametrical analyses. The experimental and numerical results indicated that the bending capacity and the stiffness of the steel temcor joint were limited increased by increasing the gusset plate thickness. However, when the thickness of gusset plates exceeded the thickness of the flanges of the H-shaped beam, the main failure occurred on the H-shaped beam. However, those joints’ stiffness and bending capacity stopped increasing.Moreover, the bending capacity and stiffness of steel temcor joints were higher than that of aluminium temcor joints by an average of 177% and 180%, respectively. The theoretical solution for the bending capacity of steel temcor joint was proposed, and their stiffness was calculated based on Eurocode 3. Finally, the bending capacity and stiffness of the temcor joints obtained from FE models and theoretical equations were in good agreement with the experimental data.

Numerical & experimental investigation of slotted-hidden-gap connection for square HSS brace members

The Slotted-Hidden-Gap (SHG) connection represents an attractive alternative to the conventional knife plate connection for HSS braces of steel braced frames as it allows the brace to yield along its length without having to reinforce the connection. Prior studies have proven the effectiveness of this detail for circular and square HSS braces. However, no encompassing seismic design method or detailing rules exist for SHG square HSS members. To gain deeper insight into the behaviour of the SHG connection, a preliminary numerical parametric study of square HSS braces under a monotonic tension loading protocol was done to further investigate key factors influencing the connection's performance. The weld size and length as well as the gusset plate thickness are critical in the design of SHG connections and may hinder the connection performance if poorly designed or fabricated. A laboratory testing program, of four SHG HSS ASTM A1085 (254 × 254 × 13) brace specimens with different weld configurations, was also carried out. Keeping a 20 mm overlap length despite changing the overall weld size and length was sufficient to develop the yield resistance of the braces and to force fracture away from the connection region. Utilizing longer length smaller sized welds granted an additional 3.1% of brace strains compared to connections with shorter welds.

Cold-formed steel beam-to-column bolted connections for seismic applications

Cold-formed steel (CFS) portal frames are gaining increased popularity around the world. The structural performance of these frames is to a large extent controlled by the CFS beam-to-column connections, which in most practical applications transfer the loads through the beam web using a gusset plate, while the flanges are left unconnected. This can lead to premature local buckling failure of either the CFS beam web in the connection zone or the gusset plate, leading to poor seismic performance. This paper aims to develop two new connection configurations which engage the flanges in the connection behaviour. In conjunction, practical seismic design recommendations are presented, which allow a balance between the load carrying capacity of the connections and their seismic performance to be reached. Detailed Finite Element connection models, taking into account material nonlinearity and initial geometric imperfections, are developed and validated against experimental data. The validated FE models are then used to conduct a comprehensive parametric study to investigate the effects of key design parameters, including the beam thickness and the gusset plate shape and thickness, on the moment–rotation behaviour of the connections. Based on the results, suitable connections, which balance strength with seismic performance, are introduced. Their seismic performance is evaluated in terms of ductility, energy dissipation and damping coefficient, leading to some practical design recommendations commensurate with different seismic performance levels.

Behavior of different bolted connection configurations in frames composed of cold-formed sections

Rigid bolted cold-formed steel connections have been very popular for their better distribution of straining actions and for better full-filling serviceability requirements. However, the behavior of every single element in the connection as well as the interaction between them is not clear due to its complex behavior. A nonlinear finite element parametric study was conducted on the apex knee connection of a portal frame constructed with cold-formed back-to-back double-lipped C sections for both the rafter and the column. These back-to-back lipped C sections, connected by gusset plates are used as beam and column members. Only the webs of lipped C sections are connected to the connection gusset plates with bolts. The section flanges are not connected to the columns for ease of construction. The study focused on investigating the effect of different parameters on the ultimate capacity and the failure mode of the eave connection. Studied parameters include different bolt configurations, bolt diameters, gusset plate thickness, the bolt pre-tensioning force, and the edge distance. The effect of bolt bearing on the C-section web was considered in the calculation of the capacity of the connection. Five modes of failure were identified namely; lateral out-of-plane buckling of the gusset plate, local buckling of the connected section, bolt bearing of C-section web and the gusset plate, tearing of C-section web. It was observed that bearing failure is the dominant mode of failure. However, in some cases, the lateral-out-of-plane buckling of the gusset plate takes place and causes the premature failure of the connections at low values of applied loads. The local failure of the connected sections occurs at the ultimate loading phase. Several observations were found and some useful recommendations for optimum connection configuration are suggested. A simple interaction design procedure for special configuration to calculate the resistance of the joint connection under moment, shear, and normal forces based on the bolt bearing failure for different bolt pitches is proposed.

Mechanical properties of T-plate stiffened gusset joints for aluminum alloy single layer two-way grid shells

The mechanical performance of T-plate stiffened gusset (TSG) joints for aluminum alloy single layer two-way grid shells is presented in this paper. Firstly, a kind of TSG joints for aluminum alloy spatial structures is proposed to improve the mechanical behavior of gusset joints. Secondly, six full-scale specimens, including unstiffened gusset (USG) joints, plate stiffened gusset (PSG) joints in literatures and TSG joints, are tested under monotonic loads to investigate their flexural capacity. Thirdly, the design parameters of TSG joints, such as gusset plate thickness, beam height, beam width, beam flange thickness, beam web thickness, T-plate flange thickness and T-plate web thickness, are studied through numerical analyses. The experimental and numerical results indicate that TSG joints can show better out-of-plane mechanical properties than USG and PSG joints. Finally, the bearing capacity prediction methods for TSG joints are provided based on theoretical analyses.

Advanced Design of Block Shear Failure

This paper presents the behaviour and design procedure of bolted connections which tend to be sensitive to block shear failure. The finite element method is employed to examine the block shear failure. The research-oriented finite element method (RFEM) model is validated with the results of experimental tests. The validated model is used to verify the component-based FEM (CBFEM) model, which combines the analysis of internal forces by the finite element method and design of plates, bolts and welds by the component method (CM). The CBFEM model is verified by an analytical solution based on existing formulas. The method is developed for the design of generally loaded complicated joints, where the distribution of internal forces is complex. The resistance of the steel plates is controlled by limiting the plastic strain of plates and the strength of connectors, e.g., welds, bolts and anchor bolts. The design of plates at a post-critical stage is available to allow local buckling of slender plates. The prediction of the initial stiffness and the deformation capacity is included natively. Finally, a sensitivity study is prepared. The studied parameters include gusset plate thickness and pitch distance.

Nonlinear FE analysis on stiffness and resistance of bolted cold-formed steel built-up joints

This paper describes a computer-based finite element (FE) approach for investigating the stiffness and resistance behaviour of beam-column moment joints in the portal frame constructed by cold-formed steel (CFS) back-to-back channel sections. A total of 8 specimens constructed by flat sheets and bolt are tested in the study. The applicability of the numerical simulation approach is validated against the experimental outcomes. Based on the FE simulations, a modified equation is proposed to predict the initial flexibility of four-layer CFS lap joints under tension. Parametric studies consisting of 18 four-layer bolted connections and 27 beam-column bolted models are conducted based on the validated model to investigate the effects of sheet width-to-thickness ratio, bolt-to-bolt hole tolerance and overlap length on the flexibility of the connection and to reveal the influence of bolt spacing, gusset plate thickness and beam profile on the failure behaviours, moment transfer coefficients and ultimate resistance of CFS beam-column moment joints. The FE obtained results indicate that increasing bolt spacing is a better option to improve the joint capacity when compared with increasing gusset plate thickness. The flexural capacity of the CFS bolted built-up joints with varying sectional configurations can meet the criterion of the existing design specifications such as Eurocode and US code.

Bearing Capacity of Steel Tube Tower Connection under Different Thickness of Gusset Plate

In this paper, a finite element model is established to study the influence of connection plate thickness on the bearing capacity of steel tube tower connections. Through the bearing capacity of connections under different connection plate thickness, the influence of connection plate thickness on the bearing capacity of steel pipe tower connections is analyzed. Finally, the relationship between the thickness of connection plates and the bearing capacity of steel tube tower connections is analyzed by regression analysis. The results show that with the increase of the thickness of gusset plate, the bearing capacity of steel tube tower connections increases linearly. The bearing capacity calculated by regression analysis is in good agreement with the finite element simulation results.

Parametric study on the I-shape brace connection of conventional concentrically braced frames

Concentrically braced frames (CBFs), designed using the conventional linear elastic method without seismic proportioning and detailing requirements, are referred to as Conventional CBFs (CCBFs) in this study. They are widely used in moderate and low seismic areas in North America due to the ease of design and economy. Without a code specified dedicated fuse member to dissipate earthquake induced energy, or a prescribed yield/failure hierarchy, the brace connection of a CCBF is usually the weakest link in the lateral load-carrying path and prone to fracture. The brace connection is therefore determinant for the structural seismic performance. In this paper, a parametric study based on a validated numerical simulation procedure was carried out on a typical I-shape brace connection, i.e. the flange plate connection. Three key design parameters, namely, the gusset plate thickness, the flange lap plate thickness, and the web lap plate thickness, were varied to study their effects on both the compressive and tensile behaviour of the brace and connection assembly. Various possible failure modes were revealed both in compression and in tension. The results showed that the brace end restraint provided by flange plate connections in CCBFs was significant; the pinned-end assumption would lead to conservative estimation of the brace buckling resistance, which might trigger detrimental gusset plate buckling. The tensile overstrength of the flange lap plate, due to the presence of transverse tensile stress along the net section, was quantified using the von Mises criterion. Design recommendations are proposed with regards to attaining better deformation capacity.

Seismic performance analysis of PBL gusset connections in buckling-restrained braced RC frames

The implementation of buckling-restrained braces (BRBs) in new reinforced concrete frames (RCFs) is more susceptible to the complex gusset connection between BRBs and the framing members. In this paper, a novel gusset connection with the L-shape perfobond strip (PBL) group was proposed to ease the installation and exhibit more reliable BRB-to-RC joints in new BRB-RCFs. Finite element (FE) monotonic pushover analysis was conducted to investigate the mechanical property of the L-shape PBL group, in terms of the effect of the gusset plate thickness, PBL arrangement and transverse rebars. An empirical formula was suggested for the optimal PBL gusset plate thickness. To gain insights into the seismic performance of the application of the PBL gusset connection in BRB-RCFs, the BRB-RCF subassemblage FE model was constructed and verified by the full-scale test. The analysis results showed that the BRB-RCF subassemblage exhibited a full hysteretic curve and more than 60% of energy was dissipated by the BRB. The gusset connection basically remained in the elastic stage and no significant damage could be observed even at 3% interstory drift ratio (IDR), which indicated that the proposed connection was effective.

Research on Mechanical Properties and Parameter Identification of Beam‐Column Joint with Gusset Plate Angle Using Experiment and Stochastic Sensitivity Analysis

Based on stochastic sensitivity analysis, a new style of joint structure with greater ductility and higher strength—the beam‐column joint with gusset plate angle (JGA) steel—was proposed. Research on the static and hysteretic behavior of the JGA was performed using finite element analysis and experimental methods. The research results indicated that adding a seat angle could increase the positive and negative initial rotational stiffness and strength and provide a better energy consumption performance of the joint. An improved chaotic particle swarm optimization (ICPSO) neural network algorithm was used to study the stochastic sensitivity. Seven important parameters that influence the bending stiffness and strength of the JGA, namely, the beam height, beam flange width, beam web thickness, gusset plate thickness, connection angle steel thickness, connection angle steel width, and seat angle steel thickness, were investigated by stochastic sensitivity analysis. Moreover, the beam height, connection angle steel, and seat angle steel thickness, which had significant influences on the mechanical properties of the joints, were studied in depth by finite element analysis. Within the range of the parameters of the joint, the higher the beam height was, the larger the connection angle thickness was; the smaller the connection angle width was, the better the joint performance was. A reasonable design of the JGA is proposed: a beam with the SH2 section (250 × 125 × 6 × 9 mm) and a 10 mm thick and 75 mm long angle steel connection.