Steel Beam-column Connections Research Articles

Behavior of steel beam section under warping using BIM program

AbstractWarping not only one of the most important phenomena in steel section it is also considered as the most complicated phenomena. Ductility, bearing capacity and serviceability of steel sections may affect by increasing stress concentration of the normal stresses due to warping. In the present work, simulation of steel beam section under effect of warping is studied. Two cantilevers connected to two columns in opposite sides with a middle steel beam-column connection to create different moments on the beam to investigate the behavior of steel section under warping using building information modeling. It is found that the stress strain relationship has four groups depending on the load intensity and the angle of rotation induced due to warping.

Seismic evaluation of steel beam-column connection equipped by circular slit dampers

AbstractThis study evaluates metallic yield dampers, specifically slit steel dampers, for protecting steel beam-to-column connections during seismic events. Finite element model simulations were conducted for the damper and its connection. Analysis of circular parameters, like the radius slot, showed that appropriately sized slit dampers exhibit advantageous seismic behavior. Moment-rotation, hysteresis curves, and plastic stresses comparisons indicate efficient energy absorption. The maximum moment was 25% lower than conventional samples. The slit steel damper model with a ductility factor of 3.5 allows significant plastic deformation before potential failure. Results emphasize the slit damper's potential for optimal performance in steel frames, suggesting its use for efficient energy absorption.

Experimental Study on Hysteretic Performance of Steel Moment Connection with Buckling-Restrained Dog-Bone Beam Sections

Steel beam–column connections with dog-bone beam sections have gained significant attention and have been extensively applied. This is attributed to their ability to effectively centralize and integrate plastic hinges, thereby diverting potential damage away from the beam ends during earthquake events. In order to achieve the enhancement of the ductility and energy dissipation of connections by inhibiting local buckling during an earthquake event, a novel steel moment connection with buckling-restrained dog-bone beam sections was proposed in this paper. There were three types of proposed connections according to the different arrangements of restrained steel plates, including arranging the restrained plates only on the flanges, only on the web, and on both the flanges and webs of the dog-bone beam sections. In this study, three specimens with buckling-restrained dog-bone beam sections and one control specimen with a dog-bone beam section were tested under cyclic loading. The failure modes, hysteretic curves, skeleton curves, stiffness degradation ductilities, displacement ductility ratios, and energy dissipation capacities of the specimens were analyzed based on the experimental results to evaluate the seismic behavior of the proposed connections. The results indicated that the local buckling of the proposed connections was significantly reduced compared with the traditional connection with a dog-bone beam section under the condition of keeping the plastic hinges away from the beam–column connection core. The arrangement of the restrained plates in the dog-bone beam section had little effect on the bearing capacity and the initial stiffness, with errors all being within 6%. It is worth mentioning that the connection with restrained plates only on the flanges in the dog-bone beam sections showed a more obvious improvement in the deformation capacity and energy dissipation capacity of the connection, which increased by 21% and 16%, respectively. Additionally, high-quality welding between the beam and column, smooth cutting shapes on the weakened flanges, and the high-quality drilling of long slots at the fixed point in the restrained plates and the dog-bone beam sections should be guaranteed to improve the hysteretic stabilities of the proposed connections.

Post-tensioned steel beam-column connections with reduced length BFRP tendons

The seismic behavior of the traditional top and seat angle beam-column connection was experimentally evaluated using a half-scaled prefabricated exterior beam-column connection subassembly. Then, an ensemble of three post-tensioned beam-column connections using reduced length basalt fiber reinforced polymer (BFRP) tendons was tested with three different tendons' post-tension (PT) force levels of 15.9, 30, and 50% of the tendons' ultimate strength. Following that, another group of three additional subassemblies containing both reduced length BFRP tendons, as post-tensioning devices, and top and seat angles, as energy dissipation (ED) devices, was tested with the same three post-tension force levels used in the previously tested group. Finally, an analytical model was proposed to capture the moment-relative rotation response of the traditional top and seat angle and the connection combining both the top and seat angles and the BFRP tendons. The results showed that connections containing BFRP tendons only, with the lowest PT force level, provided the same envelope of the top and seat angle connection, and further enhancement could be achieved by increasing the PT force level. Also, the addition of the BFRP tendons to top and seat angle connection improved the connection strength, initial stiffness, post-yield stiffness, and reduced the residual drift. In addition, the proposed analytical model predicted the moment-relative response well, which ensures the reliability of the model in designing such connections.

Finite element analysis and hysteretic model of self-centering steel connection with dual energy dissipation mechanism

In the traditional steel beam-column connection, the beam flanges were welded to the column face, while the beam web was bolted to the column face by shear tab. During seismic events, this connection often suffers from brittle failure. This paper presents a novel self-centering steel connection with dual energy dissipation mechanism. The connection utilizes the sliding of friction elements and the plastic deformation of T-stub at different stages to dissipate energy. As a result, the proposed connection not only enhances energy dissipation capacity but also increases the safety redundancy of the structure. The main focus of this study is to investigate the structural behavior of this new type of connection by refined finite element analysis models. These models are constructed using ANSYS and validated against experimental results. Furthermore, parametric analysis is conducted to investigate the influence of various factors on the seismic performance of the connection. These factors include the initial post-tensioning force of prestressed steel strands, the shape form of T-stub flange, the flange thickness of T-stub, the coefficient of friction between friction plates and web of T-stub, and the pre-tension force of high-strength bolts. The results demonstrate that increasing the initial post-tensioning force of the steel strands reduces the residual deformation and enhances the self-centering ability of the connection, and the dual energy dissipation behavior is more obvious. Meanwhile, the occurrence of both sliding and plastic deformation of T-stub is postponed. The influence of the thickness of the T-stub flange is minimal during the friction-based energy dissipation stage but significant during the energy dissipation stage of the plastic deformation of T-stub. Moreover, increasing either the coefficient of friction between friction plates and T-stub webs or the initial post-tensioning force of high-strength bolts significantly improves the bending strength of the connection and reduces residual deformation. Meanwhile, these factors mostly affect the friction sliding stage to delay the starting point of sliding, but their influence on the plastic deformation is minimal. Finally, a theoretical hysteretic model is proposed based on the dual energy dissipation mechanism. The model is compared and analyzed against experimental results, demonstrating good agreement. This provides theoretical foundation for the design of similar structural connection.

Analysis of steel beam column connection under cyclic loading with reduced web opening type fuses

Analysis of steel beam column connection under cyclic loading with reduced web opening type fuses

Experimental study on self-centering steel connections based on phased energy dissipation mechanism

Traditional steel beam-column connections and column bases often experience yield or buckling, which makes repair difficult. The recent development of resilient seismic structures has addressed this issue. Resilient seismic structures can achieve self-centering functionality through prestressed steel strands and dissipate energy through energy dissipation elements, while protecting the main components such as beams and columns from damage. This paper presents an experimental study on connections that combine friction and plastic deformation of T-stub to achieve energy dissipation. Four specimens were designed by varying the cross-sectional form of the T-stub flanges and the material of the friction plates. Quasi-static tests were conducted under low-cycle reversed loading to observe the test phenomena. The test results including moment-rotation response, deformation, stiffness, energy dissipation capacity, force of high strength strands and strain were analyzed to investigate the seismic performance of the connections. It was found that weakening the cross-section of the T-stub enabled uniform yielding and energy dissipation. Reducing the friction force between the friction plates and the T-stub web enhanced the self-centering capability while decreased the energy dissipation capacity. Overall, the connections exhibited good seismic performance.

Resilient performance of steel connections with low yield point fuses considering the effect of RC floor slab

The beam-column connection of a steel frame equipped with replaceable low yield point steel cover plates (SF-LYCP) was proposed to address the significant repair challenge and financial losses caused by beam-column connection brittle failure after an earthquake. According to an experimental study, the SF-LYCP exhibited outstanding bearing capacity, ductility, energy dissipation, and post-earthquake rapid recovery performance. To explore the effect of the reinforced concrete (RC) floor slab on the mechanical behavior of SF-LYCP in a natural working environment, the finite element method of steel beam-column connection with low yield point (LYP) steel cover plates considering the effect of the RC floor slab (SF-LYCP-RCslab) was developed and analyzed by ABAQUS. The results demonstrated that the proposed finite method was able to accurately predict the behavior of SF-LYCP-RCslab. The load capacity, initial stiffness, and energy dissipation capacity of the SF-LYCP-RCslab were increased in comparison to the SF-LYCP. The LYP cover plates in the SF-LYCP-RCslab still played the desirable role of structural fuses. However, the concrete of the RC floor slab had severe damage and prevented the quick replacement of repairable LYP cover plates. Based on these findings, four improved strategies for the SF-LYCP-RCslab were proposed to reduce concrete damage and increase the replacement convenience of damaged elements. Comprehensively considering the bearing capacity, ductility, energy dissipation, structural fuse function, concrete damage, and post-earthquake rapid recovery performance, the improved strategy, which adopted a profiled steel–concrete composite floor slab with a gap, was recommended in steel frame beam-column connection design.

Nonlinear analysis on mechanical behaviour of high strength steel extended endplate connections and equivalent T-stubs in fire considering axial force

In fire, ignoring the axial force acting on the high strength steel (HSS) beam-column endplate connections when considering catenary action may lead to a safety risk for the whole steel structure. Hence, a nonlinear analysis is conducted to reveal the actual performance of HSS T-stubs and HSS extended endplate connections in fire using the software ABAQUS. The ultimate displacement, failure mode and bearing capacity of HSS T-stubs under tension-shear combined action are investigated. The failure modes and moment–rotation curves of HSS endplate connections obtained by the numerical study are verified with test results in fire. Furthermore, the effects of bolt diameter, endplate thickness, endplate strength, the combination of endplate thickness and endplate strength, as well as temperature on the mechanical behaviour of HSS endplate connections considering axial force are studied. The results of nonlinear analysis are verified against Eurocode 3 Part 1–8 in various situations. The results indicate that when the shear-to-tension ratio is 2.0, the tensile bearing capacity and ultimate displacement of HSS T-stubs at 600 °C decreased to 38% and 31% of the pure tension, respectively. The parametric analysis shows that when the temperature is 600 °C, the initial stiffness and ultimate flexural capacity of connections are only about 40% and 31% of that at 20 °C.

Numerical analysis of steel beam–column connection under cyclic loading with dog bone type fuses

Numerical analysis of steel beam–column connection under cyclic loading with dog bone type fuses

An Overview of Commonly Used Steel Beam-Column Connection in Indonesia for Low-Rise Building

The Indonesian seismic provision for steel structures was initiated in 2002. The use of steel has also been increasing as a choice of structural material since then. However, there are still many weaknesses in the seismic design of steel structures that have been carried out so far. A lot of beam-column connections in steel buildings in Indonesia use a haunch in a moment-resisting connection system. Haunched systems are not described in AISC 358 as permitted connections for earthquake-resistant buildings. Recently, Europe publishes European Prequalified Steel Joints (EqualJoints). There are four types of connections discussed, and one of them is the haunched type connections. The haunched connection meets the seismic requirements to be suitable for use as an earthquake-resistant connection in Europe. This can be used as a reference if we are going to design a haunched connection in Indonesia. However, special attention should be paid to the details. The bolt configuration, the thickness of the end plates, and the shape of the haunch are not like those commonly used in Indonesia, there must be improvements to be adjusted in EqualJoints. So that the performance of the connection against earthquakes becomes more guaranteed.

Seismic behavior of steel beam-column connection with assembled steel rod energy dissipaters

The exorbitant expenses associated with the post-earthquake rehabilitation of the primary structure has been addressing the importance of a resilient building that exhibit easy and cheap repairability. To achieve a resilient building structure, a feasible way is to localize the plastic damages in preselected structural fuses which can be easily replaced. In doing so, a novel energy-dissipative steel beam-column connection incorporating the assembled steel rod energy dissipaters (ASREDs) was proposed in this paper. Firstly, the moment-resistant capacity and the rotational stiffness was theoretically derived based on a simplified mechanical-based method and the component method, respectively. Then, cyclic tests on four specimens were conducted to investigate the cyclic and recovery performance of the connection. The influences of the quantity, location, and geometrical details of the ASREDs on the performance of the connection were evaluated. The considered connection performance indexes included strength, deformability, and energy dissipation capacity. Test results showed that the proposed connections efficiently protected the primary structural members of the steel frame, i.e., beams and columns, by restricting the plastic damage within the core rod of the ASREDs. The obtained hysteretic loops were stable and plump, whereas the strength degradation was not observed until the rotation of the beam-column connection exceeded 0.03. The damaged connection was easily repaired by replacing failed ASREDs. The repaired connection exhibited identical performance with the original one. Finally, numerical models accounting for the ductile damage of ASREDs were established to reproduce the test results and to enrich the experimental database. Results showed that the numerical model could simulate the seismic behavior of connections with reasonable accuracy, and the analytical methods for predicting the performance of the connections were validated against both experimental tests and numerical simulations.

Seismic analysis and design of steel beam-column connections in Indian standard code framework

Seismic analysis and design of steel beam-column connections in Indian standard code framework

Cold Formed Steel Type C On Beams With Connection Variations

The disadvantages of using cold rolled steel (cold formed steel) include a thin profile and low stiffness of the connecting parts. Stiffness research of various types of joints is needed to study element failure, machine error or connection failure which causes the collapse of cold rolled steel structures. Analysis is needed for cantilever structures, because the maximum deflection that occurs in cantilever structures is greater than that of simply supported beam structures. The shape and type of cold rolled steel joints greatly affect the stiffness and stability of cold rolled steel structures so that the strength of several types of joints must be studied. The purpose of this study was to analyze the stiffness of the test results under the influence of bending loads on each type of cold rolled steel beam-column connection. Cold steel C channel profile with a thickness of 0.75 mm is used as the object in this study. The beam-column structure is assembled with various kinds of connections, including direct screw connections, screw-gusset plates, screw-angle plates, and screw-angle plate-gusset plates. This research shows addition of the elbow plate increases the strength of the test object by means of a screw connection and gusset plate to the load. However, the results of the maximum load in the experiment still have not reached the maximum load of the analysis results. In the screw connection the damage that occurs is tearing in the connecting plate (tear out), in the gusset plate connection the damage that occurs is the collapse of the gusset plate, in the screw-angled plate connection there are 2 damages, where the damage starts with a tear in the connecting plate ( tear out) and followed by damage to the screw that is damaged (pull out).

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.

Mechanical Performance Study of Beam-Column Connection with U-Shaped Steel Damper.

The article proposes the use of a semi-rigid energy-dissipation connection combined with a U-shaped metal damper to avoid brittle failure of rigid steel beam–column connections under seismic loading. The U-shaped metal damper connects the H-section column and the H-section beam to form a new energy-dissipation connection as an energy-dissipation member. Compared with the existing research, this connection has a stable energy-dissipation performance and great ductility. To clarify the mechanism of energy dissipation, mechanical models under two U-shaped damping deformation modes are established. The calculation formulas for the yield load and stiffness are derived for the corresponding deformation mode using the unit load method. Taking the T-shaped beam–column connection and the application of U-shaped steel damper in the beam–column connection as an example, the mechanical model of the connection is established and the calculation formulas for the yield load and stiffness are derived. At the same time, the connection is subjected to a quasi-static test under cyclic loading. The results show that the hysteretic curve of the test is complete and that the skeleton curve is accurate compared to the theory. The error range of the initial stiffness and yield load obtained by the test and the theoretical formula is kept within 20%, indicating that the theoretical formula is reasonable and feasible. In addition, the correctness of the finite element model is verified by establishing a finite element model and comparing it with the test. The mechanical responses of purely rigid connections and rigid semi-rigid composite connections are compared and analyzed using a multi-story and multi-span plane frame as an example. The results show that the model with semi-rigid connections, compared to the model with rigid connections, avoids the gradual loss of bearing capacity caused by the failure of the connection area of the second floor of the main structure and improves the seismic performance of the main structure.

Fracture analysis of high-strength steel beam-column connections with initial defects

In order to predict the ductile fracture of beam-column connections with initial defects, the finite element models of the existing Q460C high-strength steel local connection specimens were established, and J-integral, VGM and SMCS model were used to predict the fracture. Compared with the test results, the predicted results of the J-integral, VGM and SMCS model had good accuracy which verified the applicabilities of J-integral, VGM and SMCS model in fracture prediction of connections with initial defects. The finite element analyses were carried out on three full-scale cruciform Q460D high-strength steel frame beam-column connection specimens with three kinds of weld access holes. The influences of initial defect location, initial defect length, initial notch radius and weld access hole form on fracture index were studied. The results indicated that with the same initial crack length, fracture was more likely to occur at crack at flange HAZ; when the beam end load was constant, the required fracture toughness JI value increased with the increase of the initial crack length; with the same initial notch depth and initial notch radius, fracture was more likely to occur at notch at flange HAZ; the sharper the initial notch end was, the greater the stress triaxiality was and the more likely the specimen was to fracture; the weld access hole form had a significant influence on the deformation capacity of cruciform beam-column connection specimens, but had little influence on the strength of the connection specimens.

Experimental and numerical study on the performance of a novel self-centering beam-column connection equipped with friction dampers

Regarding some major issues in the behavior of steel beam-column connections such as the existence of residual drifts, low energy dissipation, different behavior in hogging and sagging moments along with the complexity of constructional details, this paper introduces a novel self-centering beam-column connection equipped with friction dampers. In this regard, two full-scale experimental specimens with two and four post-tensioned strands, were evaluated by application of a quasi-static cyclic loading protocol. Besides providing closed-form equations to estimate the forces of post-tensioned strands and the amount of connection moment, the considered finite element modeling procedure was validated using ABAQUS software. Then, the considered finite element models which meet the requirements of ACI318-19 and Eurocode3, were analyzed parametrically to study the effects of some important parameters such as the amount of strand post-tensioning and pin pre-tensioning forces, the strand diameter size along with the strand relative distance on the performance of the proposed connections. Based on the obtained results, it was observed that the proposed connection while needs less labor intensive and low installation costs, shows a stable flag-shaped hysteretic curve up to a drift of 7% without any residual rotation. Also, the required specifications to achieve the best performance of the proposed connection were introduced and the effect of variation of the considered important parameters on the energy dissipation capacity, rotational stiffness, strength and ductility of the connection was discussed. Finally, it can be concluded that the 2-strand and 4-strand connections provided the same amount of energy dissipation ratio and ductility, while the 4-strand connection had more rotational stiffness ratio and strength ratio.

Effectiveness of masonry infill walls on steel frames with different beam-column connections under progressive collapse

In this study, the effectiveness of masonry infill walls on steel frames with different beam-column connections under progressive collapse was investigated through a parametric study. A vertical force was applied to the center steelcolumn to represent the progressive collapse of steel frames. This study focused on the three most common types of steel beam-column connections found in steel structures: shear, bolted, and welded connections. Single-story (1/3 scale) steel-framed configurations with single shear and bolted beam-column connections and another infilled wall steel frame with welded connection from the literature were tested experimentally under a middle column loss event to validate the accuracy of 3D finite element models created with ABAQUS software. The verified finite element simulations were then used to study the performance of progressive collapse resistance for 12 various types of steel frames with masonry infill walls with three different types of beam-column connections. The effects of the full infilled frame, bare frame, and infilled frame with openings were explored. The size, location, and shape of the openings in the infilled frame, and the performance of these parameters with respect to the change in the type of beam-column connection were evaluated. In accordance with their mechanisms of failure and load–displacement behavior, masonry infill walls were compared in flexural and catenary action phases. The findings show that infill walls considerably improve the steel building’s structural strength and energy dissipation against progressive collapse.

Resilient steel beam-column connection with bolted compact hollow structural steel damper

This study proposes a resilience-based design approach that considers the correlation between the resilience response of self-centering post-tensioned (SCPT) steel beam to column connections and the inelastic performance of the required energy dissipation (ED) system. A compact circular hollow steel tube (CHST) is proposed as a replaceable ED system. On the basis of existing experimental results, a detailed three-dimensional finite element modeling (3D-FEM) was carried out to identify the response of the compact CHST under half cyclic loading. A large number of numerical works ended with the extraction of design charts to determine the axial strain (ΔL/L) of the ED system before encountering post-yield buckling and/or excessive strength degradation. Accordingly, in a numerical validated reference SCPT connection, several predesigned ED systems were implemented for simulation. As a result, according to the design charts, the optimum selection of proper inherent depth to thickness (D/t) ratio and length to depth (L/D) ratio of the CHST-ED system can increase the resilience of modern self-centering steel structures. In addition, the improvement of the entire connection resilience is associated with the development of satisfactory energy dissipation capacity. Furthermore, the superior performance of the connection under sequential cyclic loading promotes the application of the proposed SCPT-ED connection in a resilient structural system.