Steel Beam-column Joints Research Articles

Seismic Performance of Precast Steel Beam-Column Joint with Bolted Connection

Seismic Performance of Precast Steel Beam-Column Joint with Bolted Connection

The Hysteresis Behavior of Steel Beam–Column Joint with the Load Bearing-Energy Dissipation Connection for Converter Station Building

Prefabricated converter station building has been gradually applied in the field of power engineering construction due to the advantages of standardized design, high construction efficiency, and quality control. The beam–column joint is the essential constitutive part to ensure structural integrity and reliable force transmission for the prefabricated structure. In this paper, a novel load bearing-energy dissipation connection is proposed and applied to the beam–column joint to improve seismic performance and seismic resilience. Pseudo-static tests were conducted on the beam–column joint with the load bearing-energy dissipation connection, and the test results demonstrated that the tested beam–column joints developed with similar failure modes, and the damage was concentrated in the load bearing-energy dissipation connection while the beam and column remained elastic. The beam–column joint with the load bearing-energy dissipation connection had stable hysteresis behavior, with favorable bearing capacity and energy dissipation behavior. A shorter slip length and a larger bolt distance could lead to better stress development and enhance the bearing capacity, while the slip length barely affected the ductile behavior. Moreover, a finite element model was established and validated to extend the parametric study to provide a preliminary understanding of the mechanical mechanism of the proposed beam–column joint with the load bearing-energy dissipation connection. It was confirmed that the load–-deformation behavior was greatly affected by the slip length, but the slip length barely affected the initial stiffness. The width of the sliding steel fuse influenced the bearing capacity and the degradation behavior. A wider width could lead to a higher bearing capacity and improve the degradation behavior. Based on the analysis of the stress development and stress distribution corresponding to different feature points, it was concluded that the use of bearing-energy dissipation improved the stress development in the framing components and achieved damage concentration.

Seismic fragility and resilience assessment of steel frame with replaceable T-stub connection components

Based on a rational design, steel beam-column joints with replaceable T-stub connection components (SBCJ-RTCCs) possess superior structural fuse performance and seismic resilience performance. To further evaluate the benefits of steel frames using RTCCs in terms of dynamic response, structural and non-structural components damage as well as seismic resilience, a 12-story steel frame equipped with RTCCs (SF-RTCCs) and a steel moment resisting frame (SMRF) were designed and established. On the basis of validating the simulation results with the experimental findings, the nonlinear dynamic analyses and incremental dynamic analysis (IDA) based seismic fragility analysis was performed. The results confirm that the introducing RTCCs into steel frames can significantly mitigate base shear and floor acceleration as well as produce a more uniform inter-story deformation and a more rational yielding mechanism. Meanwhile, the SF-RTCCs can obtain comparable collapse-resistant performance compared to SMRF, and both frames possess sufficient redundancy to resist structural collapse. Thanks to the lower floor acceleration responses, the SF-RTCCSs performs much better than SMRF in controlling non-structural components damage. After DBE excitations, the probabilities of RTCCs can be replaced by 1st class and 2nd class was 17.2 % and 84.9 %, respectively. After MCE excitations, RTCCs has about 29.3 % and 67.2 % probability that it can be replaced by 2nd class and 3rd class, respectively. Considering the lower economic losses, short repair time and fewer casualties, the rating of seismic resilience of SF-RTCCs was enhanced from one-star of SMRF to two-star.

Study of Panel Zone Behavior in Interior Beam–Column Joints with Reduced Beam Section (RBS)

Based on the post-earthquake investigation of the Beiling and Hanshen earthquakes, many welded rigid beam–column joints were found to exhibit brittle failure. The failure modes of the joint region and the overall steel frame structure under the action of the earthquake need to be studied. The seismic performance of different types of weakened beam-end interior joints was investigated. The finite element method was verified by high-strength steel beam–column joint tests conducted by our research team. Finite element modeling of weakened steel beam flanges and weakened steel beam web joints was carried out based on the validated finite element modeling method. The joints were studied and analyzed using seismic parameters such as joint stress clouds, equivalent story shear–inter-story displacement ratio curves, panel zone bending moment–shear ratio curves, ductility, stiffness, and energy dissipation. The results of this study showed that honeycomb open hole-type joints exhibit a better deformation and energy dissipation capacity compared to open circular web hole-type joints. However, their load carrying capacity is reduced, which is mainly due to the larger area of the web openings. Additionally, double reduced beam section (DRBS) joints exhibit superior seismic performance and plastic hinge outward movement characteristics compared to single reduced beam section (RBS) joints. It was also found that the deformation and energy dissipation of DRBS joints and steel beam honeycomb hole-type joints are mainly borne by the beams, with the panel zone’s participation in energy dissipation accounting for a smaller proportion of the energy.

Experimental research on H-section beam-square steel column joints connected by self-tapping screws

This paper proposes a novel thin-walled steel beam-column joint entirely using self-tapping screws. Compared to bolted and welded connections, its advantages of easy construction, low precision requirements, and fast construction are suitable for low-rise steel structures. Four full-scale H-section beam-square steel column joints connected by self-tapping screws were tested and the force transfer mechanism was investigated. Three of the specimens were loaded monotonically at the beam ends. The effects of the L-shaped connecting plate thickness and the arrangement of stiffening ribs on the bending performance of the joints are analyzed. Monotonic loading tests have demonstrated that the increased thickness and the arrangement of stiffening ribs enhance the common forces in the clusters of self-tapping screws, thereby increasing the bending stiffness of the joints. One of the specimens was tested with cyclic loads. The cyclic loading test revealed that the hysteretic curve of the self-tapping screws connection is relatively full, with high energy dissipation capacity and low degradation of strength and stiffness. Finally, the improved component method proposed the calculation method of bending resistance of self-tapping connection joints. The calculation accuracy is within 10 %, which can be used as a reference for the design of bending resistance.

Experimental investigations of beam-column joints with replaceable BRFCPs using sliding restraint plates

This paper proposes a replaceable buckling-restrained flange cover plate (BRFCP) for steel beam-column joints with cantilever beam segments, in which a sliding restraint plate (SRP) with slotted holes is used to constrain the core plate buckling deformation and simultaneously control the restraint plate without significant damage. First, theoretical analyses and design considerations were presented for this joint. Second, cyclic loading tests were conducted on five joints with different BRFCP configurations, including different formats of restraint plates (discontinued or sliding restraint plates), filling plates (discontinued or sliding filling plates), and restraining gaps with different sizes. The test results showed that the damage of the proposed joint was visually observed only on the replaceable core plates and was not observed at any other structural components. The SRP can effectively constrain the buckling deformation of the core plate in comparison to the discontinued restraint plates; thus, the proposed joint showed more stable force–deformation hysteresis. The continuity of the filling plates and the restraining gap size had little influence on the overall hysteretic response of the joint. However, a larger restraining gap caused larger stress in the restraint plates. Finally, numerical models of the test joints were established in ABAQUS and validated by the test results, which can serve as a reference for further research.

Restoring force model for steel beam to CFST/HSS column joints with a reinforced concrete slab

The seismic performance of the steel beam-column joints is significantly influenced by the composite action of the reinforced concrete (RC) slab. This paper aims to propose a restoring force model for steel beam to CFST/HSS column joints with an RC slab. Based on the test results and numerical regression, a simplified trilinear skeleton curve and hysteresis rule were proposed. Secondly, a restoring force model considering the stiffness degradation was proposed. Finally, the restoring force models were compared with the finite element models. The results show that the ratio of the predicted results of the restoring force model to the finite element model (FEM) results at the yield and plastic points ranges from 0.91 to 1.10. The coefficients of variation for the two states were around 0.05, on average. The developed restoring force model provides a reliable and accurate method for evaluating the seismic performance of building structures or members.

Retracted: Mechanical Performance Analysis of Steel Beam-Column Joints in Fabricated Multirise Steel Structures after Fire

Retracted: Mechanical Performance Analysis of Steel Beam-Column Joints in Fabricated Multirise Steel Structures after Fire

Finite Element Analysis and Parametric Study of Panel Zones in H-Shaped Steel Beam–Column Joints

This paper investigates the mechanical properties of a traditional welded rigid joint with a weakened panel zone under seismic load. The created finite element model is calibrated by the high-strength steel joint test, carried out by the team in the early stage, and the effectiveness of the finite element method was verified. The finite element software ABAQUS is used to investigate the influence of different joint web thicknesses on the mechanical properties of middle column joints under a low-cyclic-loading test. Supported by a validated numerical model, the ductility, energy dissipation, and other properties of different thicknesses of panel zone column webs are carefully analyzed. The results indicate that the thickness of the web plate in the panel zone significantly affects the location of the joint plastic hinge. The ultimate loading capacity of the joints increased significantly with an increase in the thickness of the webs in the panel zones. Compared with the joint with a weakened panel zone, the hysteresis curve of the strengthened joint is fuller; meanwhile, it cannot alleviate the stress concentration at the weld holes of the web. When the thickness of the joint domain web is too weak, excessive deformation in the joint domain will lead to a decrease in the bearing capacity of the joint, causing damage. The stiffness degradation coefficient of the web-thickened specimen was found to be dominated and controlled by the stiffness of the beam; however, with an increase in the thickness of the web, the stiffness degradation coefficient remained basically unchanged. Finally, a recommendation for weakened beam–column interior joints based on the steel frame panel zone is made, which will lay a foundation for the simulation and analysis of the seismic performance of this structure.

Study of mechanical properties of H-shaped beam-column joints considering panel zone

In order to clarify the influence of panel zone (PZ) strength on the mechanical properties of each component (column, beam and PZ) of H-shaped steel beam-column joint, the equations of mathematical physics for the mechanical relationship of framing member end considering panel zone were established, and five groups of T-shaped beam-column joint specimens with different strength are tested to study the influence of panel zone to beam strength ratio (PBSR) on the deformation performance, bearing capacity and stiffness of the specimens. Through the finite element analysis, the effect of PBSR and weld access hole on the deformation of joints, the shear and flexural capacity of beams is discussed. Finally, based on the analysis of deformation and bearing capacity of the specimens and models, the reasonable value of PBSR is proposed.

Structural fuse performance and earthquake-resilient performance of beam-column joints with replaceable T-stub

In order to ensure that steel frame systems have excellent structural fuse performance and earthquake-resilient performance on the basis of good seismic performance, a novel steel beam-column joint with replaceable T-stub connection components (SBCJ-RTCCs) was proposed. The pseudo-static cyclic tests of original and replaced specimens were carried out. As an extension of the experimental tests, numerical parametric analyses were performed to determine an optimal range of resistance capacity ratio to make a balance between the seismic performance, structural fuse performance and earthquake-resilient performance. The analysis results demonstrated that despite seismic performance of specimen with a small resistance capacity ratio is relatively weak, the structural fuse performance and earthquake-resilient performance performed well. With the increase of resistance capacity ratio, the seismic performance consisting of initial stiffness and bearing capacity gradually improved. However, the plasticity and damage would be shifted from RTCCs to non-fuse components, which adversely affected the structural fuse performance, despite the earthquake-resilient performance of specimen was still good. In terms of comprehensive consideration of seismic performance, structural fuse performance and earthquake-resilient performance, the resistance capacity ratio was suggested as 0.53–0.63. Moreover, a design procedure of SBCJ-RTCCs was proposed, and its rationality was validated by a design example RT-D. The result indicates that by adopting the proposed design procedure, the RT-D exhibited stable hysteretic behavior without experiencing strength degradation. The RTCCs can play the role of structural fuses by dissipating more than 90% of the input energy, which effectively protect the non-fuse components from damage.

Experimental study of plate-buckling type earthquake-resilient prefabricated steel beam-column joints with replaceable double flange cover plates

The damage control and post-earthquake repair of beam-column joints is a hot research topic in the seismic field. Therefore, a new type of earthquake-resilient prefabricated steel beam-column joint with replaceable double flange cover plates (RFCP-ERPSJ) was proposed. The yield load of this joint can be controlled by the buckling or slip of plates, so it can be divided into plate-slipping type and the plate-buckling type. Considering that the yield load of the plate-buckling type RFCP-ERPSJ is stable, firstly, a practical design procedure and design theory of the newly plate-buckling type joint is proposed in this paper. Then, to study the seismic performance and post-earthquake repairability of this RFCP-ERPSJ, a total of 6 full-size specimens are designed and subjected to a low-cycle reciprocating loading test and constant-amplitude low-cycle fatigue test. The effects of the thickness of FCPs, the material strength of FCPs, dog-bone width, amount of FCPs connecting bolts, and bolt spacing at the middle row on the seismic performance and energy dissipation performance of the joint are studied. The experimental results are also compared with the theoretical results. The research showed that the plastic hinge of the joint could be concentrated on the replaceable FCPs, so as to protect the beams and columns. By replacing damaged FCPs and bolts, the repaired joint had the same performance as the original joint. After comparison, the theoretical yield load is in good agreement with the experimental yield load. Besides, the small thickness and dog-bone width of FCPs can reduce the load carrying capacity and energy dissipation capacity of joints, and improving the material strength of FCPs will reduce the ductility of joints and increase the risk of plastic damage to the beams and columns. If the amount of FCPs connecting bolts is reduced, the specimens mainly dissipate energy by the slip of FCPs, and the load carrying capacity will descend. Excessive bolt spacing at the middle row will reduce the load carrying capacity and energy dissipation capacity.

Numerical study on upgrading beam-column connections in steel framed buildings for progressive collapse mitigation

This research used intensive numerical analysis to identify weak points and structural issues important to limiting the spread of collapse. As a consequence, four specimens of strengthened and unstrengthened steel beam-column joint assemblies were examined using scaled models. The data were used to validate numerical models. The control specimen was a simple shear joint from one of the four experimental assemblies. The second specimen was a bolted steel beam column joint used as a reference specimen to represent the ideal beam-column joint often used in intermediate moment-resisting frames in seismic zones across the globe. The third specimen, like the control, but it had two side plates welded together to strengthen the joint site, while the fourth specimen had high-strength, hot-rolled steel bars pretensioned inside the joint zone. ABAQUS software was used to create numerical finite element models to evaluate the behavior of steel frame assemblies before and after upgrading. The FEM matrix included 22 specimens with various characteristics, including plate thickness, steel grade, a contact between beam flange-strengthening plates, and a column that was either welded or not welded in the first scheme, number and diameter of hot-rolled steel bars were for the second scheme. The effectiveness of the strengthening techniques was established by comparing the mode of failure and load–displacement characteristics of the investigated specimens.

Numerical Investigation on Progressive Collapse Mitigation of Steel Beam-Column Joint Using Steel Plates.

This research employed extensive numerical analyses to locate the weak areas and determine the structural issues critical to preventing the spread of collapse. As a result, three specimens were tested using scaled models of strengthened and unstrengthened steel beam-column joint assemblies. The data were utilized to verify numerical models. One simple shear joint from the three experimental assemblies was used as the control specimen (unstrengthened joint). The second was a bolted steel beam-column joint utilized as a reference specimen to reflect the ideal beam-column joint generally employed in intermediate moment-resisting frames in seismic zones worldwide. Similar to the control, the third specimen (strengthened joint) had two side plates welded together to strengthen the connection site. Numerical finite element models were developed using ABAQUS (2020) software to extensively investigate the behavior of steel frame assemblies before and after upgrading. The FEM matrix comprised 17 specimens with varying parameters, including plate thickness, steel grade, a joint between the beam flange-strengthening plates, and a column that was either welded or not welded. The effectiveness of the strengthening techniques was established by comparing the mode of failure and load-displacement characteristics of the investigated specimens. The results indicate that the average increase in peak load due to a change in plate thickness for grades A36 and A572 is approximately 22% and 8%, respectively. Plates made of A572 steel increase peak load by 30%. All strengthened specimens attained catenary action, mitigating the possibility of progressive collapse.

Mechanical Performance Analysis of Steel Beam-Column Joints in Fabricated Multirise Steel Structures after Fire

This study aims to analyze the mechanical properties of fabricated multistory and high-rise steel structures and steel beam-column joints after fire. Considering that the steel structure building has the characteristics of good seismic resistance, flexible structural layout, short construction period, and good safety, first, the thermal and mechanical properties of steel are analyzed. They are thermal conductivity, the thermal expansion coefficient of steel, yield strength, and elastic modulus of ordinary steel. Next, the thermal conduction principle of steel under fire environment is analyzed, including thermal conduction, thermal convection, and thermal radiation. Then, the three-story and three-span reinforced concrete is selected as the experimental object. The local frame calculation model is established through the finite element software Abaqus. It is found that when the axial compression ratio is 1.0 and the fire time of the steel body is 180 min, the vertical deformation speed of the middle column and side column of the frame will increase rapidly. Besides, the bending moment at the bottom of the side column of the frame will increase inversely. The change is not obvious when the axial compression ratio is other values. The axial deformation of the universal beam is obvious under the condition of different fire load ratios. When the load ratio increases, the maximum fire resistance of the universal beam will decrease rapidly. Meanwhile, when the steel body is subjected to the same load ratio, different bearing capacity β has little effect on the fire resistance limit of the steel body. This thesis focuses on a series of changes in the steel of fabricated multistory and high-rise steel buildings after the fire, hoping to provide a reference for the relevant teams of steel construction and make the future housing construction safer.

Electrochemical Mechanical Properties of Beam-Column Joints of Building Steel Structures under Impact Loads

To optimize the seismic performance in high-rise buildings, the performance changes of beam-column joints of high-rise steel structures of buildings when they are impacted are analyzed to obtain the optimal choice of joint combination. The most commonly used steel beam and steel column joints are selected as the research objects. Firstly, the finite element model and the shell element model of the force are established and then the model of the finite element combination of six kinds of steel beam and steel column joints is established. Secondly, the applied data of common impact force in actual buildings are collected, and the simulated impact force in this experiment is established according to the sampled data. Then, the changes in each performance of the joints under the action of the impact external force are deeply explored through simulation. Finally, the accuracy of the model is confirmed by calculation. The experimental results comprehensively show that the transmission mechanisms of the impact force are different for the six joints. Through calculation and comparison, the bending stiffness, strength, deformation, the displacement degree of the joints, and the bearing degree of the impact external force are comprehensively analyzed. It is concluded that the bolt-type and external diaphragm-type steel tube column concrete and steel-beam concrete composite joints have better seismic resistance than the other five joints. The bolt-type does not need to be welded on site, and the on-site construction workers only need to assemble, which can reduce the technical requirements for construction workers, improving the practicability and applicability. Therefore, it shows reliable reference significance for the joint selection of building steel structures.

Damage evaluation of a welded beam–column joint with surface imperfections subjected to impact loads

The weld imperfections often exist, which affect the loading capacity of the joint. The study of welded joints with surface imperfections subjected to impact loads is limited in open literature. In this study, the influence of weld surface imperfections on the performance of steel beam–column joint under impact loads is numerically investigated by using software ABAQUS. The common surface imperfections (i.e. sagging, incompletely filled groove and undercut) are considered. The damage mode, impact force and mid-span displacement of the beam–column joint with surface imperfections are obtained and compared with those of the joint without imperfection. Structural responses of the joint corresponding to various impact scenarios (i.e. different combinations of impact mass and velocity) are compared and analysed. A best-fit equation is presented to predict the maximum displacement of the joints under impact. The effects of imperfection forms and locations on the post-impact performance of the joint are also investigated, and its residual bearing capacity is compared. In addition, damage index based on the residual bearing capacity of the joint is proposed to evaluate the damage level of the joint subjected to impact. Four damage levels are defined based on the post-impact performance of the joint. The impact mass–velocity diagrams are generated to predict the damage level of the joints subjected to possible combinations of impact mass and velocity.

Experimental and FE study on strengthened steel beam-column joints for progressive collapse robustness under column-loss event

Strengthening of connections in steel framed structures is often required to mitigate the risk of progressive collapse initiated by column removal event. Steel framed buildings with simple shear connections between beams and columns are vulnerable to progressive collapse. Therefore, strengthening such structural systems for existing buildings as well as the designing of robust connections in the new structures is vital. This study was undertaken with the prime objective of investigating experimentally and numerically the efficient strengthening schemes for simple shear beam-column connections in order to minimize the risk of collapse in the incidence of sudden column loss. The experimental and numerical study includes testing a control test frame of a one-third scale single story shear-connection sub-assemblage consisting of two bays. A steel frame with an intermediate moment frame (IMF) connection was used as a target frame. Two schemes of strengthening beam-column connections were adopted for upgrading the control frame. The first scheme employed welded double side plates within the connection region, and the second scheme used pretensioned high-strength hot-rolled steel rods within the connection region. All specimens were subjected to dynamic loading in the vertical direction which essentially simulates extreme load cases like an explosion in which columns are removed. The efficacy of the strengthening schemes was evaluated based on the results of experiments and numerical simulation of the tested specimens.

An RBS-based replaceable precast concrete beam-column joint: Design approach and experimental investigation

In traditional reinforced concrete (RC) frame systems, severe damage usually occurs in the beam-column joint zone under strong earthquakes, which increases the post-earthquake repair difficulties in restoration speed and expenditure. In response to this problem, a new reduced beam section (RBS)-based steel beam-column joint for seismic-resistant precast concrete (PC) frames was proposed, to achieve the damage control for rapid replacement and restoration. The RBS-based beam-column joint (RBSJ) is installed in the beam end close to the column so that the plastic hinge will develop at the predetermined location. The design procedure of the replaceable RBSJ was developed, and the cyclic loading tests of two 1:2 scale specimens including a monolithic joint (MJ) specimen and a RBSJ specimen were carried out. Test results demonstrated that the proposed RBS-based joint exhibited expected failure mode and excellent hysteretic response, compared with the monolithic joint. Additionally, the damaged RBSJ specimen was subsequently replaced in situ for three times, and the quasi-static test was performed for each replaceable specimen. The test results demonstrated the replaced RBSJ specimens behaves the same behavior as the origin specimen, indicating the proposed joint was feasible in precast RC framed structures.

Progressive Collapse Performance of Steel Beam-to-Column Connections: Critical Review of Experimental Results

Background: The steel beam-to-column connections are vulnerable structural elements when a building loses one or more of its vertical load-carrying components due to abnormal or accidental loading conditions. After a column is destroyed by abnormal loads, the tensile axial force of the beam gradually increased, while the bending moment decreased, and the load-resistance mechanism shifts from a flexural mechanism to a catenary mechanism, with the axial force becoming the prevailing factor. Aims: This paper investigates the progressive collapse performance of steel beam-to-column connections. While undergoing large deformation, the beam-to-column connections are subjected to moment, shear, and tension in conjunction with high ductility demand. Their behavior under monotonic loading depends on the moment-axial tension interaction and greatly affects the progressive collapse resistance of the structure. This paper presents a critical review of experimental tests of different types of steel beam-column joints (flexible, rigid, and semi-rigid) under a central-column-removal scenario. Methods: The experimental results, including load-deformation relationships, failure modes, and catenary effects, are described in detail. The findings are used to evaluate the rotation capacity of different types of steel beam-to-column connections. The results are compared to the acceptance criteria specified by the main progressive collapse guidelines for several beam-to-column connection categories. Results: In simple (flexible) joints, the stiffness and strength at higher drift angles essentially depend on the tensile capacity of the connection that prevents, in some cases, the full development of the catenary mechanism. The connection depth alone does not seem to be an effective parameter to predict the rotational capacity of beam-to-column connections, since different connections with similar values of the connection depth result in very different values of the maximum rotation capacity. In fully rigid and semi-rigid connections, after the column removal, the flexural resistance controls the behavior at the preliminary phase, and the tensile force is almost zero. With increased downward displacement, the axial tensile force also increases, developing a catenary mechanism. Although the stiffness of rigid and semi-rigid connections is higher than flexible connections, both categories result in similar rotation capacity. Conclusion: In all the simple connections herein considered, the plastic rotation capacity obtained by tests was found much higher than the code recommended values that are probably too conservative. On the contrary, for one rigid and two semi-rigid connections, the values of the plastic rotation capacity obtained by tests are lower than the corresponding recommended values. Thus, the suggested acceptance criteria proved to be out of the conservative side.