• Steel and Composite Structures
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• v.31 no.5
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• pp.453-467
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• 2019

Portal frame structures, made up of cold-formed steel trusses, are increasingly being used for lightweight building construction. A novel pin-jointed moment connector, called the Howick Rivet Connector (HRC), was developed and tested previously in T-joints and truss assemblage to determine its reliable strength, stiffness and moment resisting capacity. This paper presents an experimental study on the HRC, in moment resisting cold-formed steel trusses. The connection method is devised where intersecting truss members are confined by a gusset connected by HRCs to create a rigid moment connection. In total, three large scale experiments were conducted to determine the elastic capacity and cyclic behaviour of the gusseted truss moment connection comprising HRC connectors. Theoretical failure loads were also calculated and compared against the experimental failure loads. Results show that the HRCs work effectively at carrying high shear loads between the members of the truss, enabling rigid behaviour to be developed and giving elastic behaviour without tilting up to a defined yield point. An extended gusset connection has been proposed to maximize the moment carrying capacity in a truss knee connection using the HRCs, in which they are aligned around the perimeter of the gusset to maximize the moment capacity and to increase the stability of the truss knee joint.

• Steel and Composite Structures
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• v.47 no.3
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• pp.375-382
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• 2023

The H-shaped steel beam is popular due to its ease of manufacturing and connection to the column. This profile, which is used as a shallow beam, needs the high weak-axis bending stiffness and torsional stiffness to meet the overall stability. Achieving the local beam flange stability, bearing capacity, bending stiffness, and torsional requirements need a great thickness and width of the beam flange, which causes, which will cause more uneconomical structural design. So, the box-section beam is the ideal alternative. However, the current design specifications do not have design rules for the bolt-and-welded connection of the box-section beam and box-section column. The paper proposes a novel bolt-and-welded connection of the box-section beams and box-section columns based on a high-rise structural design scheme. Three connection models, BASE, WBF, and RBS, are analyzed under cyclic loading in ABAQUS software. The failure modes, hysteresis response, bearing capacity, ductility, plastic rotation angle, energy dissipation, and stiffness degradation of all models are determined and compared. Compared with the other two models, the model WBF exhibited excellent seismic performance, ductility, and plastic rotation ability. Finally, model WBF was chosen as the connection scheme used in the project design.

• Steel and Composite Structures
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• v.27 no.3
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• pp.337-353
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• 2018

In previous weak-axis moment connection tests, brittle fracture always initiated near the edge of the beam flange groove weld due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the China NSFC (51278061) study, this paper tested two full-scale novel weak-axis reduced beam section moment connections, including one exterior frame connection specimen SJ-1 under beam end monotonic loading and one interior frame joint specimen SJ-2 under column top cyclic loading. Test results showed that these two specimens were able to satisfy the demands of FEMA-267 (1995) or ANSI/AISC 341-10 (2010) without experiencing brittle fracture. A parametric analysis using the finite element software ABAQUS was carried out to better understand the cyclic performance of the novel weak-axis reduced beam section moment connections, and the influence of the distance between skin plate and reduced beam section, a, the length of the reduced beam section, b, and the cutting depth of the reduced beam section, c, on the cyclic performance was analyzed. It was found that increasing three parametric values reasonably is beneficial to forming beam plastic hinges, and increasing the parameter a is conducive to reducing stress concentration of beam flange groove welds while increasing the parameters b and c can only reduce the peak stress of beam flange groove welds. The rules recommended by FEMA350 (2000) are suitable for designing the proposed weak-axis RBS moment connection, and a proven calculation formulation is given to determine the thickness of skin plate, the key components in the proposed weak-axis connections. Based on the experimental and numerical results, a design procedure for the proposed weak-axis RBS moment connections was developed.

• Advances in concrete construction
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• v.14 no.3
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• pp.195-204
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• 2022

As a brittle failure mode, punching-shear failure can be widely found in traditional RC slab-column connections, which may lead to the entire collapse of a flat plate structure. In this paper, a novel RC slab-column connection with inner steel truss was proposed to enhance the punching strength. In the proposed connection, steel trusses, each of which was composed of four steel angles and a series of steel strips, were pre-assembled at the periphery of the column capital and behaved as transverse reinforcements. With the aim of exploring the punching behavior of this novel RC slab-column connection, a static punching test was conducted on two full-scaled RC slab specimens, and the crack patterns, failure modes, load-deflection and load-strain responses were thoroughly analyzed to explore the contribution of the applied inner steel trusses to the overall punching behavior. The test results indicated that all the test specimens suffered the typical punching-shear failure, and the higher punching strength and initial stiffness could be found in the specimen with inner steel trusses. The numerical models of tested specimens were analyzed in ABAQUS. These models were verified by comparing the results of the tests with the results of the analyzes, and subsequently the sensitivity of the punching capacity to different parameters was studied. Based on the test results, a modified critical shear crack theory, which could take the contribution of the steel trusses into account, was put forward to predict the punching strength of this novel RC slab-column connection, and the calculated results agreed well with the test results.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.215-221
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• 2014

To satisfy the high voltage direct current (HVDC) grid connection demand for wind power generation system, a novel topology and control strategy of HVDC grid connection for open-winding permanent magnet synchronous generator (PMSG) based wind power generation system is proposed, in which two generator-side converter and two isolated DC/DC converters are used to transmit the wind energy captured by open winding PMSG to HVDC grid. By deducing the mathematic model of open winding PMSG, the vector control technique, position sensorless operation, and space vector modulation strategy is applied to implement the stable generation operation of PMSG. Finally, the simulation model based on MATLAB is built to validate the availability of the proposed control strategy.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.466-472
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• 2013

The paper presents a novel DC grid connection topology and control strategy for doubly-fed induction generator (DFIG) based wind power generation system. In order to achieve the wind power conversion, the stator side converter and the rotor side converter is used to implement the DFIG control based on the indirect air-gap flux orientation, and a DC/DC converter is used for the DFIG system to DC grid connection. The maximum power point tracking and DC voltage droop control can also be implemented for the proposed DFIG system. Finally, a 4-terminal DFIG-based multi-terminal DC grid system is developed by Matlab to validate the availability of the proposed system and control strategy.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.381-394
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• 2019

If an alternative path would not be considered for redistribution of loads, local failure in structures will be followed by a progressive collapse. When a vertical load-bearing element of a steel structure fails, the beams connected to it will lose their support. Accordingly, an increase in span's length adds to the internal forces in beams. The mentioned increasing load in beams leads to amplifying the moments there, and likewise in their corresponding connections. Since it is not possible to reinforce all the elements of the structure against this phenomenon, it seems rational to use other technics like specified strengthened connections. In this study, a novel connection is suggested to handle the stated phenomenon which is introduced as a passive connection. This connection enables the structure to tolerate the added loads after failing of the vertical element. To that end, two experimental models were constructed and thereafter tested in half-scale, one-story, double-bay, and bolted connections in three-dimensional spaces. This experimental study has been conducted to compare the ductility and strength of a frame that has ordinary rigid connections with a frame containing a novel passive connection. At last, parametric studies have been implemented to optimize the dimensions of the passive connection. Results show that the load-bearing capacity of the frame increased up to 75 percent. Also, a significant decrease in the displacement of the node wherein the column is removed was observed compared to the ordinary moment resisting frame with the same loads.

• Steel and Composite Structures
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• v.47 no.3
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• pp.315-337
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• 2023

The steel structure is an assembly of individual structural members joined together by connections. The connections are the focal point to transfer the forces which is susceptible to damage easily. It is challenging to replace the affected connection parts after an earthquake. Hence, steel plates are utilised as a structural fuse that absorbs connection forces and fails first. The objective of the present research is to develop a beam-column end plate connection with single and dual fuse and study the effect of single fuse, dual fuse and combined action of fuse and damper. In this research, seismic resilient beam-column end plate connection is developed in the form of structural fuse. The novel connection consists of one main fuse was placed horizontally and secondary fuse was placed vertically over main fuse. The specimens are fabricated with the variation in number of fuse (single and dual) and position of fuse (beam flange top and bottom). From the fabricated ten specimens five specimens were loaded monotonically and five cyclically. The experimental results are compared with Finite Element Analysis results of Arunkumar and Umamaheswari (2022). The results are critically assessed in the aspect of moment-rotation behaviour, strain in connection components, connection stiffness, energy dissipation characteristics and ductility. While comparing the performance of total five specimens, the connection with fuse exhibited superior performance than the conventional connection. An equation is proposed for the moment of resistance of end-plate connection without and with structural fuse.

• Steel and Composite Structures
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• v.23 no.2
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• pp.161-172
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• 2017

A new composite tube connection method called the pre-tightened teeth connection technique is proposed to improve the composite tube connection efficiency. This paper first introduces the manufacturing process of the proposed technique. It then outlines how the mechanical properties of this technology were tested using four test groups. The factors that influence the load-bearing capacity and damage model of the connection were analyzed, and finally, the transfer load mechanism was investigated. The following conclusions can be obtained from the research results. (1) The new technique improves the compressive connection efficiency by a maximum of 79%, with the efficiency exceeding that of adhesive connections of the same thickness. (2) Changing the depth of teeth results in two types of damage: local compressive damage and shear damage. The bearing capacity can be improved by increasing the depth, length, and number of teeth as well as the pre-tightening force. (3) The capacity of the technique to transfer high loads is a result of both the relatively high interlaminar shear strength of the pultruded composite and the interlaminar shear strength increase provided by the pre-tightening force. The proposed technique shows favorable mechanical properties, and therefore, it can be extensively applied in the engineering field.

• Steel and Composite Structures
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• v.6 no.3
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• pp.237-255
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• 2006

This paper presents a novel analytical formulation for the analysis of composite beams with partial shear interaction stiffened by a bolted longitudinal plate accounting for time effects, such as creep and shrinkage. The model is derived by means of the principle of virtual work using a displacement-based formulation. The particularity of this approach is that the partial interaction behaviour is assumed to exist between the top slab and the joist as well as between the joist and the bolted longitudinal stiffening plate, therefore leading to a three-layered structural representation. For this purpose, a novel finite element is derived and presented. Its accuracy is validated based on short-and long-term analyses for the particular cases of full shear interaction and partial shear interaction of two layers for which solutions in closed form are available in the literature. A parametric study is carried out considering different stiffening arrangements to investigate the influence on the short-and long-term behaviour of the composite beam of the shear connection stiffness between the concrete slab and the steel joist, the stiffness of the plate-to-beam connection, the properties of the longitudinal plate and the concrete properties. The values of the deflection obtained from the finite element simulations are compared against those calculated using the effective flexural rigidity in accordance with EC5 guidelines for the behaviour of elastic multi-layered beams with flexible connection and it is shown how the latter well predicts the structural response. The proposed numerical examples highlight the ease of use of the proposed approach in determining the effectiveness of different retrofitting solutions at service conditions.