• Steel and Composite Structures
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• v.32 no.3
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• pp.337-346
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• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.27-37
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• 2012

The construction of a moment connection for a rectangular hollow section (RHS) column and a H-shaped beam is difficult because the RHS is a closed section. When a inner diaphragm is used for such a connection, in general, it is installed after cutting the HSS columns, which results in increased construction work. This paper suggests a new fabrication method to overcome such problems: An inner diaphragm is welded to inside a C-shaped section first, and then a column is fabricated by welding two C-shaped sections. This fabrication method is superior to a classic method in terms of constructibility. An experimental and a numerical study using Ansys 9.0 were performed in order to compare the strength of connections with respect to the presence of concrete, the corner shape of diaphragm, and the axis of loading. The experimental results including initial stiffness and ultimate loads are reported and the analytical results including load transfer mechanism, degree of stress concentration, and strain distribution are also reported.

• Earthquakes and Structures
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• v.4 no.2
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• pp.203-217
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• 2013

In recent decades, it has been realized that increasing the lateral stiffness of structure subjected to lateral loads is not the only parameter enhancing safety or reducing damage. Factors such as ductility and damping govern the structural response due to lateral loads. Despite the significant contribution of damping in resisting lateral loads, especially at resonance, there is no accurate mathematical representation for it. The main objective of this study is to develop a damping identification procedure for linear systems based on a mixed numerical-experimental approach, assuming viscous damping. The proposed procedure has been applied to a laboratory experiment associated with a numerical model, where a hollow rectangular steel cantilever column, having three lumped masses, has been fixed on a shaking table subjected to different exciting waves. The modal damping ratio has been identified; in addition, the effect of adding filling material to the hollow specimen has been studied in relation to damping enhancement. The results have revealed that the numerically computed response based on the identified damping is in a good fitting with the measured response. Moreover, the filling material has a significant effect in increasing the modal damping.

• Computers and Concrete
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• v.30 no.2
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• pp.127-141
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• 2022

In this paper, a numerical procedure is proposed for achieving the minimum cost design of reinforced concrete polygonal column cross-sections under compression and biaxial bending. A methodology is developed to integrate the metaheuristic algorithm Quantum Particle Swarm Optimization (QPSO) with an algorithm for the evaluation of the strength of reinforced concrete cross-sections under combined axial load and biaxial bending, according to the design criteria of Brazilian Standard ABNT NBR 6118:2014. The objective function formulation takes into account the costs of concrete, reinforcement, and formwork. The cross-section dimensions, the number and diameter of rebar and the concrete strength are taken as discrete design variables. This methodology is applied to polygonal cross-sections, such as rectangular sections, rectangular hollow sections, and L-shaped cross-sections. To evaluate the efficiency of the methodology, the optimal solutions obtained were compared to results reported by other authors using conventional methods or alternative optimization techniques. An additional study investigates the effect on final costs for an alternative parametrization of rebar positioning on the cross-section. The proposed optimization method proved to be efficient in the search for optimal solutions, presenting consistent results that confirm the importance of using optimization techniques in the design of reinforced concrete structures.

• Steel and Composite Structures
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• v.41 no.6
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• pp.861-871
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• 2021

This study aims at investigating the hysteretic performance of a novel composite wall panel fabricated by infilling aerated concrete blocks into a novel light-steel frame used for low-rise residential buildings. The novel light-steel frame is consisted of two thin-wall rectangular hollow section columns and a truss-beam assembled using patented U-shape connectors. Two bare light-steel frames and two composite wall panels have been tested to failure under horizontal cyclic loading. Hysteretic curves, lateral resistance and stiffness of four specimens have been investigated and analyzed. Based on the testing results, it is found that the masonry infill can significantly increase the lateral resistance and stiffness of the novel light-steel frame, about 2.3~3 and 21.2~31.5 times, respectively. Failure mode of the light-steel frame is local yielding of the column. For the composite wall panel, firstly, masonry infill is crushed, subsequently, local yielding may occur at the column if loading continues. Hysteretic curve of the composite wall panel obtained is not plump, implying a poor energy dissipation capacity. However, the light-steel frame of the composite wall panel can dissipate more energy after the masonry infill is crushed. Therefore, the composite wall panel has a much higher energy dissipation capacity compared to the bare light-steel frame.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.27-36
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• 2010

It is well known that the shear strength of an RC column subjected to a lateral force decreases with the increase of the displacement ductility of column. This decreasing rate of shear strength is quite dependent on the initial shear strength. Therefore, the evaluation of the initial shear strength is important to predict the shear strength with reasonable accuracy. The shear behavior is complex because many parameters, such as the sectional shape, aspect ratio, axial force, longitudinal bars and ductility, are mutually interactive. In this study, the initial shear strength has been investigated by experiments varying parameters such as the aspect ratios, void ratios, ratio of longitudinal bars and sectional types. A new empirical equation for the initial shear strength, considering the ratio of the longitudinal bars, has been proposed and its validity has been assessed.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.67-76
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• 2006

In this paper the moment transfer efficiency of a web and the strain concentration at the RHS (Rectangular Hollow Section) column-to-steel beam connections was evaluated. Initially, non-linear finite element analysis of five bare steel beam models was conducted. The models were designed to have different detail at their beam-to-column connection, so that the flexural moment capacity was different respectively. Analysis results showed that the moment transfer efficiency of the analytical model with RHS-column was poor when comparing to model with WF(Wide Flnage)-column due to out-of-plane deformation of the RHS-column flange. The presence of scallop and thin plate of RHS column was also a reason of the decrease of moment transfer efficiency, which would result in a potential fracture of the steel beam-to-column connections. Analytical results were compared with the previous experimental results. The analytical and the previous experimental results showed that the strain concentration was inversely proportional to the moment transfer efficiency of a beam web and the deformation capacity of connection was poor as their moment transfer efficiency degrades. Further finite element analyses of composite beam with a floor slab revealed that the neutral axis moved toward the top flange and the moment transfer efficiency of a beam web decreased, which led to premature failure of the connection.

• Steel and Composite Structures
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• v.12 no.1
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• pp.73-92
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• 2012

The effect of element interaction and material nonlinearity on the ultimate capacity of stainless steel plated cross-sections is investigated in this paper. The focus of the research lies in cross-sections failing by local buckling; member instabilities, distortional buckling and interactions thereof with local buckling are not considered. The cross-sections investigated include rectangular hollow sections (RHS), I sections and parallel flange channels (PFC). Based on previous finite element investigations of structural stainless steel stub columns, parametric studies were conducted and the ultimate capacity of the aforementioned cross-sections with a range of element slendernesses and aspect ratios has been obtained. Various design methods, including the effective width approach, the direct strength method (DSM), the continuous strength method (CSM) and a design method based on regression analysis, which accounts for element interaction, were assessed on the basis of the numerical results, and the relative merits and weaknesses of each design approach have been highlighted. Element interaction has been shown to be significant for slender cross-sections, whilst the behaviour of stocky cross-sections is more strongly influenced by the material strain-hardening characteristics. A modification to the continuous strength method has been proposed to allow for the effect of element interaction, which leads to more reliable ultimate capacity predictions. Comparisons with available test data have also been made to demonstrate the enhanced accuracy of the proposed method and its suitability for the treatment of local buckling in stainless steel cross-sections.

• Steel and Composite Structures
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• v.3 no.3
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• pp.153-168
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• 2003

This paper discusses the results and observations from a large-scale fire test conducted on a slim floor system, comprising asymmetric beams, rectangular hollow section beams and a composite floor slab. The structure was subjected to a fire where the fire load (combustible material) was higher that that found in typical office buildings and the ventilation area was artificially controlled during the test. Although the fire behaviour was not realistic it was designed to follow as closely as possible the time-temperature response used in standard fire tests, which are used to assess individual structural members and forms the bases of current fire design methods. The presented test results are limited, due to the malfunction of the instrumentation measuring the atmosphere and member temperatures. The lack of test data hinders the presentation of definitive conclusions. However, the available data, together with observations from the test, provides for the first time a useful insight into the behaviour of the slim floor system in its entirety. Analysis of the test results show that the behaviour of the beam-to-column connections had a significant impact on the overall structural response of the system, particularly when the end-plate of one of the connections fractured, during the fire.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.37-47
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• 2010

In order to attain enhanced seismic performance of RC bridges, premature shear failure prior to the achievement of target ductilities of the piers should be prevented. For this purpose, a reliable shear strength evaluation is required. The shear strength of an RC column subjected to a lateral force decreases with an increase in ductility. Many empirical equations for the shear strength have been proposed by many researchers. However, there are many discrepancies in the initial shear strength in the low ductility range, and in the decrease rate according to the ductility. In this study, a new empirical equation of shear strength considering the displacement ductility effect has been proposed, in which the initial shear strength equation proposed by the authors was revised on the basis of the investigation of many other researchers' test results. The resulting improvement in accuracy is confirmed by comparison with other empirical equations.