Behavior Of Gusset Plate Connections Research Articles

A practical analytical model for special concentrically braced frames

Special concentrically braced frames (SCBFs) are extensively used in high seismicity regions because of structural efficiency and high ductility for energy dissipation. SCBFs exhibit large inelastic deformation through tensile yielding, buckling and post-buckling behaviors of braces. A simple and accurate model for brace with low computational cost is vital to capture the complex structural behavior of SCBFs. The previous researches generally recommended ten elements per brace, which significantly increases both modeling and computer time. In this paper, a new hybrid flexibility-based beam-column element, considering initial geometrical imperfection and residual stress explicitly, distributed plasticity along member length, and semi-rigid behavior of gusset plate connections is proposed for modeling of SCBFs. It is worth to point out that the zero-length springs attached to element ends for simulation of gusset plate connections can consider the influence of axial force, which has not been reported in literature. Furthermore, the influences of initial geometrical imperfection and residual stresses on the performance of SCBFs are firstly evaluated on the basis of direct analysis method (DAM) specified in AISC360 (2016) and Eurocode-3 (2005). As all dominant factors affecting structural behaviors have been considered, the proposed method using one-element-per-member model provides sufficiently accurate results for practical design with enhancement of computational efficiency. Several examples illustrate the accuracy and efficiency of the proposed model for performance-based seismic design of SCBFs.

Cyclic Performance of Braces with Different Support Connections in Special Concentrically Braced Frames

Gusset plate connections between the steel braces and the supporting frame members play an important role in the performance of special concentrically braced frames (SCBFs) under earthquake loading conditions. Extensive studies have been conducted on SCBFs in which the gusset plate connections are designed to ensure the out-of-plane buckling of steel braces. However, research on the cyclic behavior of gusset plate connections allowing the in-plane buckling of braces is very limited. An experimental investigation has been carried out in this study to investigate the cyclic performance of the in-plane buckling of gusset-brace assemblies. Tests showed that the gusset plate connections detailed for in-plane buckling of braces provided performance at par with those detailed for the out-of-plane deformation arrangement. A numerical comparative study on three types of connection arrangements has also been conducted, namely, a) out-of-plane buckling of braces using gusset plates, b) in-plane buckling of braces using knife plates, and c) direct connection of braces without using any gusset plates. Braces made of hollow steel sections having constant slenderness ratio and width-to-thickness ratio are used in all the numerical models. The main parameters compared are the energy dissipation capacity, displacement ductility, patterns of failure, and the sequence of yielding in the components. Both test and analysis results are used to quantify the performances of gusset plate connections in order to achieve an efficient and reliable concentrically braced frame systems.

On‐line hybrid test method for evaluating the performance of structural details to failure

SummaryA test environment to evaluate the seismic performance of gusset plate connections intended for steel braced frames is proposed. The developed test method combines the substructuring techniques with finite element analysis methods in an on‐line hybrid scheme. Numerical substructure analysis is conducted on bracing members, while bracing connections are treated as experimental substructures. A force‐displacement combined control imposed with the aid of 2 jacks ensures physical continuity between the analysis and test. The rotational behavior of gusset plate connections subjected to large inelasticity and varying axial loading until fracture is investigated. Two gusset plate details were designed and tested to verify the efficiency of the proposed method. The test method is rational, and smooth operation is achieved. The test results revealed the advantage of the developed on‐line hybrid test method in exploring the ultimate capacity of bracing connections.

BEHAVIOUR OF A GUSSET PLATE CONNECTION UNDER COMPRESSION

The paper presents behaviour of gusset plate connections in compression. The finite element method is employed to examine the buckling resistance of the gusset plate connections. The FE model is validated to results of physical tests and verified by an analytical solution based on existing formulas. Finally, a parametric study is performed. The studied parameters include gusset plate thickness and size, types of connection between the gusset plate and frame members and stiffeners.

Inelastic buckling and post-buckling behavior of gusset plate connections

In this study, by using finite element non-linear static analysis and comparing it with experimental models, the buckling and post-buckling behavior of bracing gusset plates has been investigated. The effects of such parameters as dimension and thickness of the gusset plate and the influence of position of the bracing member on the behavior of gusset plate have been examined. The results of the analyses clearly suggest that capacity, buckling and post-buckling behaviors of gusset plates depend on the position of the bracing splice plate with respect to the free bending line as well as on the size and thickness of the gusset plate. Also, with respect to numerical analysis results, some practical graphs for the calculation of buckling capacity of gusset plate connections are presented. For steel structures, the proposed method is apparently more accurate than available code procedures.

Compressive Behavior of Gusset Plates Connected with Single-Angle Members

AbstractGusset plate connections with single-angle steel members are commonly used in power transmission towers. However, little research has been carried out with regard to the compressive behavior and design of gusset plates connected with single-angle members. Due to the complexity of the connections and load eccentricity, it is difficult to predict the compressive strength of the gusset plates. In this study, two full-scale experimental tests and a numerical parametric study were conducted to investigate the compressive behavior of such gusset plate connections. In the tests, the buckling failure mode and lateral-torsional deformation were observed. Finite-element (FE) models were then established and validated through comparison against the test results. In the parametric study, the effects of gusset plate thickness, unbraced length, distance to bending line, and load on the adjacent bracing member were examined. On the basis of the findings of this study and currently available design methods, two d...

Post-buckling resistance of gusset plate connections: Behaviour, strength, and design considerations

This paper presents a numerical study on the buckling behaviour of gusset plate connections under compression. The main focus is given to the post-buckling resistance of relatively slender gusset plate connections, cases which are commonly found in thin gusset plates in light-weighted structures, and also potentially, as driven by the recent development in steel manufacture industry, in high-strength steel (HSS) gusset plates. The numerical modelling strategy was carefully validated using the results of eight full scale tests previously conducted by the authors and co-workers, and an extensive parametric study was subsequently performed covering a reasonably wide range of geometric configurations and material properties of practical gusset plate connections. Stable post-buckling equilibrium paths were observed for the models with relatively thin gusset plates, and the use of HSS further promotes remarkable post-buckling resistance. The influences of initial imperfection and material strain hardening on the buckling behaviour of gusset plate connections have also been discussed in detail. Based on the results from the numerical study, two design approaches were proposed, namely, Column Buckling Approach, which is based on a modified column analogy from the current design practice, and Plate Buckling Approach, which is based on a plate analogy and modified Winter formulae. While both methods can be used by practicing engineers, the latter may take account of the plate action of gusset plates in a more reasonable manner, and it is also more consistent with the common design rules for plated structures.

Compressive strength and behaviour of gusset plate connections with single-sided splice members

Due to the ease of fabrication and construction, gusset plate connections with single-sided splice members are a popular connection type in building frames and light structures. However, this detail produces local out-of-plane eccentricity, which can be detrimental to the ultimate strength of the connections. This paper presents experimental, numerical, and analytical investigations of the compressive behaviour of eccentrically loaded gusset plate connections. Three full-scale tests were conducted, including two specimens with unstiffened splice members and the remaining one with stiffened splice members. The ultimate loads of the three specimens were found to be evidently less than the concentrically loaded specimen which has been earlier reported. Finite element (FE) models were then established, which were validated through comparisons against the test results. The sensitivity of the FE models to the initial imperfections was also studied. An extensive parametric study was subsequently performed, and the influences of varying gusset plate and splice member geometric configurations were discussed in detail. Three key failure modes were identified for the eccentrically loaded gusset plate connections, namely, Gusset–Splice Interactive Plastic Failure (G–SIPF), Splice Plastic Failure (SPF), and Gusset Plate Buckling (GPB). A set of design rules based on the nature of each failure mode was proposed accordingly, where good agreements were observed between the FE and the design results in terms of both the ultimate load and the governing failure mode. Worked examples were finally provided to clearly illustrate the proposed design procedure.

Behaviour of gusset plate connections to ends of round and elliptical hollow structural section members

Gusset plate connections to the ends of hollow structural section (HSS) members are regularly used in steel-framed buildings and roof trusses. Recent research on this connection type has indicated that current design recommendations for preventing tensile failure induced by shear lag may be overly conservative. This paper presents an experimental study on 13 gusset plate end connections to circular and elliptical HSS members under quasi-static tension and compression loadings. Current design proposals found in research studies and in design guides and specifications are compared with the experimental work. Various fabrication details for this connection type have been considered, and the influence of connection length, gusset plate orientation (in the tube long side versus short side), and distance between welds has been studied. In the experimental study, failure of all specimens under tensile loading was caused by circumferential fracture of the HSS or by tear-out of the HSS base material along the weld. The compression specimens failed by local buckling of the HSS at the connection end. A preferred static design approach for such connections is thus recommended.Key words: gusset plate, hollow section, tube, connection, round, elliptical, shear lag, tear-out failure.

Gusset plate connections under monotonic and cyclic loading

A numerical investigation of the monotonic and cyclic behaviour of steel gusset plate connections is conducted using a nonlinear finite element model. Successive versions of the model, which include the effects of framing member stiffness, nonlinear material behaviour, initial imperfections, and bolt slip, are formulated and validated by comparison with test results. A parametric study is then conducted to examine the effects of the load sequence and the interaction between the gusset plate and the brace member under cyclic loading. This investigation demonstrates that the cyclic behaviour of gusset plate connections can be modelled accurately using a simplified finite element model. Gusset plate – brace member subassemblies, wherein the gusset plate is designed as the weak element in compression rather than the brace member, are shown to have stable behaviour under cyclic loading and better energy absorption characteristics than similar subassemblies with the brace member designed as the weak element in compression.Key words: steel, connections, gusset plates, cyclic loading, concentric bracing, buckling.

Behavior and design of gusset plate connections in compression

A total of thirteen full-scale tests were conducted to investigate the compressive behavior and strength of gusset plate connections. The test parameters included gusset plate thickness, size, and brace angle. In addition, the effects of frame action on the compressive behavior of gusset plate connections were also investigated. In general, the gusset plate specimens were failed by sway buckling of the connection since no out-of-plane restraint was provided from the bracing member. The test results indicated that, in general, significant yielding of the gusset plate specimens occurred prior to reaching the ultimate load. However, only limited yielding was observed for the thin specimens with a plate thickness of 6.5 mm. The ultimate load of the specimens increased almost linearly proportional to the gusset plate thickness and decreased with increasing plate size. A slight decrease in the ultimate load of the specimens was observed when a 30° brace angle was used instead of a 45° one. The beam and column moment had only negligible effects on the ultimate load of the specimens; however, yielding of the specimens was detected at a load level significantly lower than that had no framing moment. The numerical simulation provided good agreement with the test results.

Elastic Buckling Strength of Gusset Plate Connections

To investigate the elastic compressive behavior of gusset plate connections, eight tests are performed with gusset plate thickness, gusset plate size, and out‐of‐plane restraint of the diagonal bracing member as test parameters. The effects of the framing members on the gusset plate are neglected in the testing program. It is found that the primary failure mode of gusset plate connections loaded in compression is gusset plate buckling. The buckling can be classified as sway buckling and local buckling depending on the out‐of‐plane restraint of the diagonal bracing member. The elastic buckling strength of the specimens is affected significantly by the gusset plate thickness and the out‐of‐plane restraint of the bracing member. The finite‐element analysis by the program ANSYS gives reasonable predictions of the buckling strength of the gusset plate connection. A parametric study was performed using ANSYS. It is found from the parametric study that splicing member should always be extended toward the beam an...

Stability and ductility of steel structures under cyclic loading

MATERIAL PROPERTIES AND PLASTICITY MODELS: The Experimental Basis of Material Constitutive Laws of Structural Steel under Cyclic and Nonproportional Loading (G.C. Lee, K.C. Chang, and K. Sugiura). Instability of Steel Short Column under Cyclic Loadings (K. Sugiura, E. Watanabe, G.C. Lee, and K.C. Chang). Bounding Surface Plasticity Model for Steel under Cyclic Loading (Y.F. Dafalias). A Uniaxial Stress-Strain Model for Structural Steels under Cyclic Loading (E. Mizuno, C. Shen, Y. Tanaka, and T. Usami). High Performance Steels for Earthquake Resistant Building Structure in Japan (H. Kuwamura). Experimental Observations: Cyclic Behavior of Gusset Plate Connections in V-Braced Steel Frames (A. Astaneh). Cyclic Post-Buckling Behavior of Steel Bracing Members (S.C. Goel). Cyclic Local Buckling of EBF Shear Links with or without Axial Force (K. Kasai and E.P. Popov). Stability of Beams in Eccentrically Braced Frames (M.D. Engelhardt, K.C. Tsai, and E.P. Popov). Buckling and Fracture in Cyclically Loaded Truss Girders (C.C. Chen and L.W. Lu). Steel and Concrete-Filled Steel Compression Members under Cyclic Loading (T. Usami, S. Mizutani, T. Aoki, and Y. Itoh). Ductility and Ultimate Strength of Concrete-Filled Steel Members (T. Kitada). Ductility of Steel Bridge Piers from Dynamic Loading Tests (K. Kawashima, G.A. MacRae, K. Hasegawa, T. Ikeuchi, and K. Oshima). Experimental Investigation on Hysteretic Behavior of Thin-Walled Box Beam-to-Column Connections (N. Nishimura, W.S. Hwang, and Y. Fukumoto). Experiments on Partially Encased Composite Columns (K. Takanashi and A.S. Elnashai). Substructured Hybrid Earthquake Loading Test of Steel Box Pier Models (Y. Yamada, H. Iemura, W. Tanzo, M. Yasuda, and S. Oka). Analytical Modeling: Numerical Experiment on Buckling/Plastic Collapse Behavior of Plates under Cyclic Loading (T. Yao and P.I. Nikolov). Multi-Spring Joint Model for Inelastic Behavior of Steel Members with Local Buckling (K. Ohi and K. Takanashi). Modelling of Hysteretic Behavior of Thin-Walled Box Members (E. Watanabe , K. Sugiura, T. Mori, and I. Suzuki). Prediction of Damage and Residual Strength of Tubular Member under Collision (H. Murakawa, Y. Ueda, and D. Xiang). Toward a Mythology of Cyclic Lateral Buckling of Beams (K.D. Hjelmstad). Cyclic Plastic Collapse of Steel Planar Frames (K. Uetani). Ultimate Energy Absorption Capacity of Moment Frames under Earthquakes (H. Akiyama). Design Implementation: Width-to-Thickness Ratios for Plate Elements in Earthquake Engineering Design of Steel Structures (Y. Fukumoto and Y. Itoh). Earthquake Resistant Design of Ductile Braced Steel Structures (S.C. Goel). Analysis and Design of Steel Braces and Braced Frames in Building Structures (M. Nakashima and M. Wakabayashi). Seismic Resistant Design of Steel Moment Resisting Frames Considering Panel-Zone Deformations (W. F. Chen and J.Y.R. Liew). Estimation of the Deformation Capacity of Steel Bridge Piers (G.A. MacRae and K. Kawashima). Future Research Needs. Future Research Needs (T.V. Galambos). Appendix A - The State of the Art: Ductility and Cyclic Buckling - A Japanese Contribution in the Field of Civil Engineering (E. Watanabe and M. Dogaki). Appendix B - Seminar Attendees. Author Index.