• Advances in Computational Design
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• v.3 no.1
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• pp.17-34
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• 2018

Tall buildings are categorized as important structures because of the large number of occupants and high construction costs. The choice of competent lateral load resisting systems in tall buildings is of crucial importance. Bracing systems have long been an economic and effective method for resisting lateral loads in steel structures. However, there are some potential adverse aspects to bracing systems such as the limitations they inflict on architectural plans, uplift forces and poor performances in compression. in order to eliminate the mentioned problems and for cost optimization, in this paper, six 20-story steel buildings and frames with different types of bracing, i.e., conventional, mega-scale and buckling-restrained bracing (BRB) were analyzed. Linear and modal push-over analyses were carried out. The results pointed out that Mega-Scale Bracing (MSB) system has significant superiority over the conventional bracing type. The MSB system is 25% more economic. Some other advantages of MSB include: up to 63% less drift ratio, up to 38% better performance in lateral displacement, up to 100% stiffer stories, and about 50% smaller uplift forces. Moreover, MSB equipped with BRB attests even a better seismic behavior in the aforementioned parameters.

• Steel and Composite Structures
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• v.28 no.2
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• pp.139-147
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• 2018

Moment frames have considerable ductility against cyclic lateral loads and displacements; however, sometimes this feature causes the relative displacement to exceed the permissible limits. This issue can bring unfavorable hysteretic behavior on the frame due to the reduction in the stiffness and resistance against lateral loads. Most of common bracing systems usually control lateral displacements through increasing stiffness while result in decreasing the capacity for energy absorption. This has direct effect on hysteresis curves of moment frames. Therefore, a system that is capable of both having the capacity of energy absorption as well as controlling the displacements without a considerable increase in the stiffness is quite important. This paper investigates retrofitting of a single-storey steel moment frame using a delayed wire-rope bracing system equipped with the ductile middle steel plate. The steel plate is considered at the middle intersection of wire ropes, where it causes cables to be continuously in tension. This integrated system has the advantage of reducing considerable stiffness of the frame compared to cross bracing systems as a result of which it could also preserve the frame's energy absorption capacity. In this paper, FEM models of a delayed wire-rope bracing system equipped by steel plates with different geometries have been studied, validated, and compared with other researchers' laboratory test results.

• Steel and Composite Structures
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• v.36 no.2
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• pp.197-211
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• 2020

Application of the steel ring as a type of seismic fuse has been one of the efforts made by researchers in recent years aiming to enhance the ductility of the bracing systems which in turn, possesses various advantages and disadvantages. Accordingly, to alleviate these disadvantages, an innovative bracing system with a diamond scheme equipped with a steel ring is introduced in this paper. In this system, the braces and yielding circular damper act in parallel whose main functionality is to increase ductility, energy absorption and mitigate drawbacks of the existing bracing systems, in which the braces and yielding circular damper act in parallel. To conduct the experimental tests, specimens with three types of rigid, semi-rigid and pinned connections were built and subjected to cyclic loading so that their performance could be analyzed. Promisingly, the results indicate both great applicability and efficiency of the proposed system in energy absorption and ductility. Moreover, it was concluded that as the braces and damper are in parallel, the use of a steel ring with smaller size and thickness would result in higher energy absorption and load-resisting capacity when compared to the other existing systems. Finally, to assess the potential of numerically modeling the proposed system, its finite element model was simulated by ABAQUS software and observed that there is a great agreement between the numerical and experimental results.

• Smart Structures and Systems
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• v.4 no.5
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• pp.685-696
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• 2008

This paper deals with the numerical model of a bracing-friction damper system and its deployment using the optimal slip load distribution for the seismic retrofitting of a damaged building. The Slotted Bolted Connection (SBC) type friction damper system was tested to investigate its energy dissipation characteristic. Test results coincided with the numerical ones using the conventional model of a bracing-friction damper system. The placement of this device was numerically explored to apply it to the assumed damaged-building and to evaluate its efficiency. It was found by distributing the slip load that minimizes the given performance indicies based on structural response. Numerical results for the damaged building retrofitted with this slip load distribution showed that the seismic design of the bracing-friction damper system under consideration is effective for the structural response reduction.

• Journal of the Korean Institute of Rural Architecture
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• v.18 no.3
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• pp.35-42
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• 2016

For the reason of economy, farmers and structural engineers prefer the vinyl house frame members that have the lightest cross sections. Therefore, in order to reach this aim, rod bracing system is the best method for multiple vinyl house frames. In this study, wire rods (tension members) are used to be bracing members in multiple vinyl house frames. The effects of additional wire rods in the frames are investigated by the variations of the bending moments, axial forces, displacements and combined stresses in the main frames that are reinforced by different shapes of rod bracing system. Vinyl house frames are usually made by steel pipe members and collapsed by the excessive wind and snow loads. Two kinds of bracing models are used for wind and snow loads separately in this study. The effective bracing models for each load are finally figured out.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1205-1219
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• 2016

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the self-centering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.1-9
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• 2014

Improving the earthquake resistance of buildings through seismic retrofitting using steel braces can result in brittle failure at the connection between the brace and the building, as well as buckling failure of the braces. In this study, a non-compression cross-bracing system using the Carbon Fiber Composite Cable (CFCC), which consists of CFCC bracing and bolt connection was proposed to replace the conventional steel bracing. This paper presented the seismic resistance of a reinforced concrete frame strengthened using CFCC X-bracing. Cyclic loading tests were carried out, and the maximum load carrying capacity and ductility were investigated, together with hysteresis of the lateral load-drift relations. Test results revealed that the CFCC X-bracing system installed RC frames enhanced markedly the strength capacity and no buckling failure of the bracing was observed.

• Smart Structures and Systems
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• v.8 no.2
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• pp.205-217
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• 2011

This article describes the research work involving the implementation of an Active Bracing System aimed at the modification of the initial dynamics of a laboratorial building structure to a new desired dynamics. By means of an adequate control force it is possible to assign an entirely new dynamics to a system by moving its natural frequencies and damping ratios to different values with the purpose of achieving a better overall structural response to external loads. In Civil Engineering applications, the most common procedures for controlling vibrations in structures include changing natural frequencies in order to avoid resonance phenomena and increasing the damping ratios of the critical vibration modes. In this study, the actual implementation of an active system is demonstrated, which is able to perform such modifications in a wide frequency range; to this end, a plane frame physical model with 4 degrees-of-freedom is used. The Active Bracing System developed is actuated by a linear motor controlled by an algorithm based on pole assignment strategy. The efficiency of this control system is verified experimentally by analyzing the control effect obtained with the modification of the initial dynamic parameters of the plane frame and observing the subsequent structural response.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.3
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• pp.133-140
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• 2014

The friction damper can be used for improving the seismic resistance of existing buildings. The damper is often installed in bracing members. The energy dissipation capacity of the damping systems depends on the type of the structure, the configuration of the bracing members, and the property of dampers. In Korea, there are numerous low- to mid-rise reinforced concrete moment frames that were constructed considering only gravity loads. Those frames may be vulnerable for future earthquakes. To resolve the problem, this study developed a toggle bracing system with a high density friction damper. To investigate the improvement of reinforced concrete frames after retrofit using the developed damped system, experimental tests were conducted on frame specimens with and without the damped system. The results showed that the maximum strength, initial stiffness and energy dissipation capacity of the framed with the damped system were much larger than those of the frame without the damped system.

• Architectural research
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• v.24 no.3
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• pp.75-84
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• 2022

Scads of earthquake-resistant systems are being invented around the globe to ensure structural resistance against the lateral forces induced by earthquake loadings considering structural safety, efficiency, and economic aspects. Shear wall and Bracing systems are proved to be two of the most viable solutions for seismic strengthening of structures. In the present study, three numerical models of a G+10 storied building are developed in commercial building analysis software considering shear wall and bracing systems for earthquake resistance. Material nonlinearity is introduced by using plastic hinges. Analyses are performed utilizing two dynamic methods: Response Spectrum analysis and nonlinear Time-history analysis using Kobe and Loma Prieta earthquake data and results are compared to observe the nonlinear behavior of structures. The outcomes exposed that a significant increase in the seismic responses occurs due to the nonlinearity in the building systems. It was also found that building with shear wall exhibits maximum resistance and minimum nonlinearity when subjected to dynamic loadings.