Beam Connections Research Articles

Assessment of the beam configuration effects on designed beam–column connection structures using FE methodology based on experimental benchmarking

Abstract Purpose This article aims to investigate the structural behavior of beam–column joints subjected to axial force. The geometry used is the addition of a number of beam connections to the column, and the differences in the numbers of beams used are 1, 2, 4, and 4, denoted as V1, V2, V3, and V4, respectively. Design/methodology/approach In this work, the analysis was performed using the numerical finite element method with ABAQUS software. A benchmarking analysis was also conducted to validate the numerical results. Findings Several numerical simulations showed that of the variations tested, the V2 model demonstrated the highest force value among the four test models, at 130.883 kN. The displacement caused by the force was 227.32 mm, which was the lowest value among the four test models. On the other hand, the V3 model received the smallest force value among the four test models, at 24.576 kN, with a displacement of 227.49 mm. The displacement value was greater than that for the V2 model, further indicating that the V2 model was the stiffest of the four models tested. Originality/value This study shows that the influence of beam–column joint geometry is not limited to double-extended end-plate bolted connections.

Some Considerations on the Behaviour of Bolted Stainless-Steel Beam-to-Column Connections: A Simplified Analytical Approach

Stainless-steel has proven to be a first-class material with unique mechanical properties for a variety of applications in the building and construction industry. High ductility, strain hardening, durability and aesthetic appeal are only a few of them. From a specific point of view, its nonlinear stress–strain behaviour appears capable of providing a significant increase in the rotational capacity of stainless-steel connections. This, in turn, may provide significant benefits for the overall response of a structure in terms of capacity and ductility. However, the bulk of the research on stainless-steel that has been published so far has mostly ignored the analysis of the deformation capabilities of the stainless-steel connections and has mostly focused on the structural response of individual members, such as beams or columns. For such a reason, the present study aims to contribute to the general understanding of the behaviour of stainless-steel connections from a conceptual, numerical and design standpoint. After a brief review of the available literature, the influence of the use of stainless-steel for column–beam connections is discussed from a theoretical standpoint. As a novel contribution, a different approach to compute the pseudo-plastic moment resistance that takes into account the post-elastic secant stiffness of the stainless-steel is proposed. Successively, a refined finite element model is employed to study the failure of stainless-steel column–beam connections. Finally, a critical assessment of the employment of carbon-steel-based design guidelines for stainless-steel connections provided by the Eurocode 3 design (EN 1993-1-8) is performed. The findings prove the need for the development of novel design approaches and more precise capacity models capable of capturing the actual stainless-steel joint response and their impact on the overall ductility and capacity of the whole structure.

Multi-span composite girders with composite dowels – Experimental investigations and design approach to account for the beneficial effect of shear force redistribution along the composite interface

The broad use of composite dowels as shear connectors in multi-span steel and concrete composite members is currently hindered by insufficient regulations for hogging moment regions, where the connectors are located in cracked concrete slabs and have reduced shear resistance. This paper reports on the results of three beam tests that illustrate the ability of continuous steel and concrete composite beams with composite dowels to redistribute shear forces from impaired connectors located in hogging bending regions to intact connectors in sagging bending regions. The effect of concrete cracking on the load-bearing behaviour of composite dowels is analysed with regard to their strength, stiffness and ductility by means of three full-scale member tests. This paper proofs the existence of a beneficial shear force redistribution process along the interface of multi-span composite members and quantifies the shear force transfer occurring between connectors in sagging and hogging bending regions. In addition, the paper provides an economical design method for continuous composite girders. Previously developed models regarding the shear resistance of single composite dowels in cracked concrete are refined aiming to provide both safety and ease of use. These models are subsequently extended into a comprehensive design strategy that allows us to consider the beneficial shear force redistribution processes along the interface when designing the shear connection of multi-span composite beams with composite dowels.

Design Recommendations for Columns Made of Ultra-High-Performance Concrete and NiTi SMA Bars

The use of new materials in construction endows structures with better mechanical characteristics. The combination of ultra-high-performance concrete (UHPC) and nickel and titanium (NiTi) shape memory alloy (SMA) improves the behavior of building structures by increasing both their ductility and dissipation energy due to the low-damage and self-centering properties of NiTi SMA. Since UHPC and NiTi SMA are expensive materials and still scarce in distribution channels, this article tries to offer design recommendations to reduce the length of the column-beam connection in which these new materials should be introduced, leaving the rest of the column with conventional materials. To achieve this, a nonlinear static pushover analysis of columns using finite element software, SeismoStruct, was performed. This model was calibrated using experimental results. Next, a parametric analysis was carried out to propose the design recommendations. Results indicated that an adequate design for the column–beam connection, considering both economy and performance, should include a main zone with UHPC and SMA reinforcements, a transition zone with UHPC and steel reinforcements, and another zone with conventional reinforced concrete. The transition zone improved the hybrid column’s performance without excessively raising the cost. The main zone length, the transition zone length, and the strength of the concrete in the rest of the column must be determined to ensure that the critical section of the column was in the main zone to develop the maximum strength and ductility. The length of the main zone depended on the compressive strength of the conventional concrete, the relative axial load of the column, and the required ductility.

Seismic Performance of Self-Centering Square Concrete-Filled Steel Tubular Column-to-Steel Beam Connection under Variable Axial Force

A self-centering square concrete-filled steel tubular column-to-steel beam connection with bolted angles was designed and its behavior analyzed theoretically. Three ½-scale specimens differing only in the loading procedure of the vertical force were tested under cyclic loading conditions. A finite element (FE) model of the self-centering connection was established in the ABAQUS software and its validity verified against experimental results. Compared with experiments, an extended parameter analysis of the variable axial force with a wider variation range of axial force and variable axial force in imitation ground motion was conducted using the proposed FE model. The experimental results showed that specimens with larger axial forces and variable axial forces consumed more energy and had clearer residual drifts compared with those of specimens with smaller axial forces and constant axial forces, respectively. The simulation results showed that a larger axial force considerably decreased the resistance capacity of the lateral load, resulting in a descending skeleton curve. A clear residual drift and asymmetry in the maximum relative rotation were observed under positive and negative displacement upon increasing the axial forces. In addition, a larger range of change in the axial force resulted in a more prominent residual drift compared with a smaller range of change in the axial force under a relatively small lateral displacement, decreasing the reliability of the self-centering capacity of the connection during an earthquake.

Pembinaan Tukang Mengenai Sambungan Baja Pada Bangunan Gedung di Kecamatan Sekarbela Kota Mataram

The availability of land for the residential area is becoming scarce in Mataram, The capital city of West Nusa Tenggara. In response to this situation, the construction of high buildings becoming a trend. A trend that initiating a new quandary as this city is located in a high-risk area, prone to earthquakes. Still fresh in our memory, when this area was struck by a series of earthquakes in 2018, two major shocks of 7 and 6,9 magnitude were followed by thousands of aftershocks. Therefore, means are needed to mitigate the risk, for instance reinforcing the utilization of steel. Steel is known for its capacity to withhold immense quakes. Melted connecting plates and cracked connecting bolts are frequent issues in high building construction, often leading to the faulty building. Hence, educating craftsmen on steel structure connection is essential. This community service is done by training craftsmen after acquiring data regarding their capabilities. On the training day, craftsmen were taught by the community service team regarding frame connection, column beam connection, the connection of sub-beam main beam, and base plate connection. The craftsmen are given time to discuss with the community service team. The evaluation shows, there is an increase in craftsmen performance scores after receiving the training, there was an increase of 44,74 or equivalent to 112,225%.

Demountable connections for enhanced resilience: An analytical and numerical assessment of steel-concrete composite beams

To improve the increasingly serious environmental pollution problems such as construction dust and waste in the process of construction and reconstruction phase, the full life-cycle demountable structures have attracted increasing interest in earthquake engineering. This paper describes a new type of demountable shear connection for the steel-concrete composite beams to realize reuse in full-life cycle at service loads and rapid return to occupancy after damage under seismic actions. The structural configuration and mechanical feature of this composite beam were first introduced. After the nonlinear finite element (FE) models using the Abaqus software had been validated against experimental data, a parametric study was carried out to understand the effect of bolt diameter, bolt strength grade, precast concrete plug size, strength of precast concrete plug and slab on the shear behavior of demountable shear connections at the component level. The results show that bolt diameter and strength grade have a significant effect on the shear capacity and stiffness, respectively. Besides, bolt strength grade and concrete plug size can improve the performance level of reuse and occupancy. Based on the FE analysis results, simple design calculation method for demountable shear connection is proposed. Finally, behavior of the proposed steel-concrete composite beam was also evaluated under two-point loading to exhibit the performance of reuse and replaceability in engineering practice.

Behaviour and design of steel and composite beam connections to composite walls

This paper presents a combined experimental and numerical study on the static and cyclic behaviour of composite wall-to-steel/composite beam connections. In the experimental phase, seven composite wall-to-steel beam connections fabricated from both S250 mild steels and S690 high-strength steels were tested under static and cyclic loads. Owing to the adoption of various design solutions, tested composite wall-to-steel beam connections exhibited significant different failure modes. However, all of such steel beam connections exhibited satisfactory rotational capacities. Meanwhile, six composite wall-to-composite beam connections were fabricated from S250 mild steel and tested under both static and cyclic loads. On the contrast, less ductile performance of these composite beam connections was observed, as the reinforcement failed to reach yielding. In order to further investigate the design details that can enhance mechanical properties of both composite wall-to-steel/composite beam connections, the authors herein developed finite element models and validated with the obtained experimental results. Extensive following numerical analyses were performed regarding both composite wall to steel and composite beam connections. Finally, practical design recommendations were proposed.

Experimental and numerical studies on seismic behavior of new cross square hollow column-truss beam connections

Five cyclic tests on the specimens were conducted to investigate seismic behavior of new cross square hollow column-truss beam connections. The variables are beam, column section size and axial force ratio. The paper reports on the failure modes, hysteretic curves, ultimate load carrying capacity, ductility, energy dissipation capacity, and stiffness degradation of the specimens. Two types of failure modes, i.e., column failure and beam failure mode, were found from the tests. The specimens experiencing the column failure mode exhibit poor seismic performance due to the overall instability induced by the occurrence of the plastic hinge of the column. While, the specimens displaying the beam failure mode exhibit well seismic behavior owing to the redistribution of the plastic stresses among the members of the truss beam. Noteworthy, the failure mode will change from column failure to beam failure when the column thickness increases and the axial force ratio decreases. Additionally, in the beam failure mode, the increase of the column thickness can improve the connection’s bearing and energy dissipation capacity, while the impact of the axial force ratio can be ignored. Based on the test results, the limit value of axial force ratio corresponding to the boundary failure mode under different column thicknesses is determined by using the nonlinear numerical model.

Seismic behaviour of Concrete-filled steel tubular column to H-Shape steel beam connection with side plate

To ensure the quality of filled concrete and improve the indoor utilization rate of steel frame structure residential buildings, a novel concrete-filled steel tubular (CFST) column to H-shape steel beam connection with side plate was proposed in this study. Six specimens of 1/3 scale were tested under reversed cyclic loading. To evaluate the hysteretic performance, failure mode, ductility, stiffness degradation, strength degradation and energy dissipation capacity. The evaluation parameters include the axial load ratio, and the side plate height and thickness. The results indicated that the failure mode mainly exhibited the steel beam buckling failure, making all hysteretic curves exhibit typically spindle-shaped. The equivalent viscous damping coefficient is 0.305–0.394. The average story drift angle at the ultimate stage is 1/31 ∼ 1/37. It shows that all connections possess sufficient energy dissipation capacity and excellent ductility. The peak and ultimate load are significantly reduced with the increase of the axial load ratio. And the secant stiffness increases in the elastic stage with the rise of the thickness and height of the side plate. Finally, the failure mode, hysteresis curve, and envelope curve achieved from the finite element method(FEM) established in this paper are consistent with the test results. And the FEM disclosed that the beam flange stress is transferred to the side plate through the fillet weld, and the side plate stress is transferred to the column panel through the fillet weld.

Analysis of Sika Cim Additive Material Proportion In Beam-Column Joint for Fabricated House

The design compressive strength (f’c) is 21,7 Mpa / K250 and the chemical liquid was used is Sika Cim. Variation of Sika Cim adding that used is 0%; 0,3%; 0,5%; 0,8%; 1%; and 1,2% toward the weight of cement used. The each variation consists of 3 sample with 2 sample that will be at compressive strength tested at the age of 7 days, and 2 sample for compressive strength control that tested at the age of 28 days. From these all variations of Sika Cim adding, the optimum point for connection material can be founded and then it will used to fabricated house panel assembling which analise damage model of the connection. Then calculating the cost that used to make connection with the optimum Sika Cim adding, and then compare it with the cost of normal concrete with same quality. From this study can be founded that level of optimum Sika Cim is 2263,54 ml or 0,52% from the cement which used for 1 m3 volume of the concrete.. Level of Sika can increase 11,8 MPa of compressive strength or 58,38% from the normal concrete without Sika Cim. Sika Cim using at K200 concrete to produce K250 concrete is 1182,219 ml/m3, with 7,48% cost from total cost for each K200 readymix concrete. This Sika Cim adding can economize the cost for about Rp. 51.397,67 for each m3 concrete. The composition of the mixture with the optimum Sika Cim applied to the precast column beam connection material, produces a joint that has a good crack pattern.

Influence of H-column stiffness on the anti-collapse performance of composite frame in the minor-axis direction

This study is the first attempt to investigate the resistance mechanism in the minor axis of H-columns and aims to provide essential information for improving the reliability of the anti-collapse transmission path of spatial structures. A one-third scale composite frame extending in the minor-axis direction of the H-column, comprising a welded flange and bolted web beam–beam connection, was investigated through monotonic static loading test to clarify the resistance transmission mechanism of structures. Based on the progress in the internal force under different displacements, the minor-axis specimen experienced stages of elasticity, compression arch, and mixed mechanism. The influence of column stiffness on the resistance and internal force development in the minor-axis specimen was comparatively significant with respect to the results of the major-axis specimen. For parametric analysis, a full-scale model was developed, which confirmed the influence of column stiffness and boundary axial restraint stiffness on collapse performance of composite frames in the minor-axis direction, providing an underlying mechanism for anti-collapse design and optimization research. Furthermore, a multispan solid model was developed to reflect the attenuation law of the axial restraint stiffness provided by the external substructure (surroundings) with the appropriate number of spans, which assisted in formulating a simplified modeling process. To avoid or delay the negative impact of potential defects on the structure, local weakening strategies were applied to the minor-axis direction based on the experimental and simulation results, and the collapse resistance mechanism was verified using the developed model.

An Intelligent Disaster Prediction in Communication Network Using OAN-ANFIS Technique Based on TEM Feature Selection Approach

Abstract: Due to facility damage and a lack of power, natural disasters disrupt vital services. When the main nodes of a hierarchical network, such as a cellular communication system, are compromised or overloaded, major communication failures frequently happen over a large geographic area. High throughput satellite (HTS) is one of the best options for disaster management as an alternate communication capability since it offers effective communication for a large area regardless of the availability of conventional terrestrial infrastructures. Conventional HTS, on the other hand, uses fixed beam bandwidth and connections for relaying data, making it ineffective when communication demand spikes in a disaster area. Therefore, the work has developed an Intelligent Disaster prediction in a communication network that alters and empowers the decision-making process to avoid a False alarm rate toward transmitting data to the digital world in a better way using the OAN-ANFIS technique based on the TEM Feature selection approach. To limit the likelihood of inaccuracy, the suggested framework first preprocesses the data by transforming unstructured data into arranged manner. The preprocessing technique handles missing values, scaling, and addressing imbalanced data. Following that, the preprocessed data is subjected to Feature selection using the TEM technique, which combines three metaheuristic algorithms, namely Xinit-FSO, LCV-ChoA, and AL-HDC, to pick the optimum feature to train the node recognition model. To obtain a high accuracy rate, the proposed Feature selection technique captures the most known feature to train the model. Finally, OAN-ANFIS predicts the various Disaster limitations of communication. The tentative outcome suggests that the proposed framework has high adaptive predictive compression approaches and achieves higher accuracy than existing strategies.

Field Demonstration of an Innovative Box Beam Connection

Field Demonstration of an Innovative Box Beam Connection

Numerical study on Role of Shear Key in Precast Beam to Beam Connection Subjected to Torsion

Connections play an important role in behaviour of precast concrete structures. It is also observed that the failure of precast building took place because of connection failure. Generally connection between precast elements are designed for axial force, shear force and bending moment. But when the precast beam supports precast slab of different span on both the side, torsional moment cannot be neglected. Therefore, it is important to study the behaviour of precast connections under the effect of pure torsional loading. In this paper effectiveness of shear key on behaviour of precast beam to beam connection under pure torsion is presented. A numerical simulation is carried out to investigate the torsional behaviour of three different type of precast wet connections with and without shear key using Finite Element Method based software ABAQUS. Projected longitudinal reinforcement of precast beam elements are welded after their erection and the gap is filled with concrete. The damaged plasticity model is employed for modelling the behaviour of concrete and elastic perfectly plastic models are employed for the modelling of behaviour of steel reinforcement. A prefect bond is assumed between the steel reinforcement and concrete. The damage along cracks, are modelled through concrete damage parameters. Precast beam connection with out shear key is considered as control beam. While other beam to beam connections have shear key of different configuration. Torque v/s twist behaviour and damage patterns as obtained from numerical analysis of different precast beam connections with shear key are compared with control specimen. Analysis results exhibited enhanced torsional strength of precast beam connection with shear key in comparison of connection without shear key.

Critical distance-based fatigue life evaluation of blunt notch details in steel bridges

Orthotropic steel deck (OSD) is applied on many bridges around the world, but its drawback of being prone to fatigue has been a concern due to the damages observed. Fatigue cracks initiated from the blunt notch details in rib-to-floor beam connections have a different fatigue behavior compared to welded connections and deserve to be investigated further. To study the effect of notch radius on the fatigue performance of blunt notch detail, 27 specimens with different geometries were manufactured and tested with fatigue loads. The fatigue lives of specimens and their crack initiation locations were investigated, and the prediction on the fatigue life of notched specimens based on the theory of critical distance (TCD) was also conducted. For notched specimens made of S355, the predicted fatigue life using the TCD method is in good agreement with the experimental results. Also, it is found that the point method has higher accuracy compared to the line method and the use of one calibration curve of notched specimens could provide enough accuracy compared to the case when two calibration curves of notched specimens are used. By modifying the mathematical description of the stress distribution near the notch root, a new formulation of the critical distance-fatigue life relationship is here proposed and validated with the experimental results.

Innovative bolted-steel box for seismic-resistant dry-precast concrete beam-column connection

Currently, many buildings are constructed with precast concrete methods. However, they still use the cast in-situ method, especially for the beam and column connection system where there are some obstacles in the casting process and the possibility of installing the reinforcement bars on site not following the design. Hence, there is potential for structural failure in that part of the connection. To reduce the connection constraints, it is proposed that the method of connecting precast concrete with an innovative connection system that is simple, lightweight, fast in the manufacturing process, can be constructed quickly and effectively on-site, and easily meets the specifications of connection quality. This proposed type of connection is a dry joint type that only uses bolts for the connection system with steel box components. This study will prove that the dry joint system can receive the moment and shear load due to earthquakes still in the elastic phase, not experiencing plasticity. The concept of connection planning does not change the concept of the Special Moment Frame System which applies the concept of Strong Column Weak Beam and Plastic Hinges. The connection is ensured in strong conditions, there is no yielding and damage at the time of a large earthquake, so the failure is not in the connection but occurs in the precast concrete block element that is at the end of the beam outside the planned connection in flexural failure with ductile behavior, not shear failure.

Seismic performance of self-centering concrete-filled square steel tubular column-to-steel beam connection equipped with SMA bolts

This study demonstrates the considerable potential of the combined application of superelastic NiTi shape memory alloy (SMA) bolts and brass friction energy dissipation devices for self-centering connections to effectively deal with both the large residual drift and lower energy dissipation of traditional connections after an earthquake. Cyclic tests were conducted on eight 1/2 scaled concrete-filled square steel tubular (CFSST) column-to-steel beam connections, including seven T-stub steel connections with SMA bolts and one conventional T-stub steel connection with normal high-strength bolts. The mechanical behavior of the connection was analyzed considering the effect of the pre-strain of the SMA bolt and the pretension force in the friction bolts through web friction devices (WFDs). The results showed that the SMA connection specimen exhibited recognizable double-flag-shaped hysteretic responses with excellent recentering ability and moderate energy dissipation capability, and the primary structural components remained elastic after each cyclic loading. The self-centering capacity of the SMA connection increases with an increase in the pre-strain of the SMA bolt, and the energy dissipation capacity of the SMA connection increases with an increase in the pre-tension force in the friction bolts. Moreover, the SMA self-centering connection has good shock resistance and repairability. After an earthquake, the seismic performance of the SMA connection can be quickly restored by replacing the T-stub steel.

Experimental and Numerical Investigation of a Disc-Spring Damage Avoidance Device in Self-Centering Slotted Beam Connections

ABSTRACT During the past decade damage avoidance initiatives have attracted considerable attention among researchers and earthquake engineers. The paper proposes a Disc Spring Damage Avoidance Device which can practically be implemented in slotted beam connections. It comprises two distinct components for self-centering and energy dissipation. The components are tested under cyclic loading and the device performance in slotted concrete joints is validated using previous experimental and analytical results. Variation in system parameters is investigated using an improved analytical model. The results show that the device can mitigate the residual displacements down to zero while maintaining a reasonable level of energy dissipation.

Seismic performance of TFOSBs bolted endplate connection to CFSST with repaired threaded holes

This paper evaluates the seismic behavior of short thread-fixed one-sided bolts (TFOSBs) bolted connection of an I-section beam to concrete-filled square steel tube (CFSST) with repaired threaded holes by enlarging threaded holes through cyclic tests. The parameters investigated were endplate thickness, inner stiffener type, thread anchored length and bolt installation sequence. The test results are presented in terms of strength, rigidity, ductility and energy dissipation capacity. Based on the experimental results: 1) the failure modes of the connections with repaired threaded holes by enlarging threaded holes were similar to the failure modes of the connections having intact hole threads; 2) the connections with repaired threaded holes exhibited 1.8% ∼ 23.8% higher ductility and 3.9% ∼ 46.6% higher energy dissipation capacity compared with the connections having intact hole threads, and the ultimate bearing capacity of those two types of joints were comparable; and 3) the bolt installation sequence has a negligible influence on the failure modes and seismic behavior of connections with repaired threaded holes. In addition, the existing calculation methods of yield moment capacity for TFOSBs bolted endplate connections under various failure modes were still suitable for connections with repaired threaded holes, and the theoretical values and test results were well-matched with errors no greater than 15%.