• Journal of Korean Association for Spatial Structures
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• v.19 no.1
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• pp.37-44
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• 2019

Yangjindang house, which is located in Sang-ju province of South Korea, is one of the special Hanok structures dated back to Joseon dynasty. This study aims to examine structural safety of the Yangjindang wood frame building considering dynamic parameters such as the natural frequency and damping ratio. The numerical model of the wood frame building is implemented using Midas Gen, especially the wood joint where column and beam were connected. The behavior of the actual frame building was compared with the modeling results. In addition, structure responses such as shear force, axial force, flexural moment and deflections were calculated and compared with the allowable limits. Numerical results show that, generally, despite of some local members shear failure, Yangjindang's structural response does not exceed the limitation according to current standards.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1A
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• pp.9-18
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• 2011

Generally the connection of structural members is assumed as hinge, rigid and semi-rigid connections. The exact tangent stiffness matrix of a semi-rigid frame element is newly derived using the stability functions considering shear deformations. Also, linearized elastic- and geometric-stiffness matrices of shear deformable semi-rigid frame are newly proposed. For the exact stiffness matrix, an accurate displacement field is introduced by equilibrium equation for beam-column under the bending and the axial forces. Also, stability functions considering sway deformation and force-displacement relations with elastic rotational spring on ends are defined. In order to illustrate the accuracy of this study, various numerical examples are presented and compared with other researcher's results. Lastly, shear deformation and semi-rigid effects on buckling behaviors of structure are parametrically investigated.

• International Journal of High-Rise Buildings
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• v.1 no.4
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• pp.311-332
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• 2012

Earthquake response of mid-rise to high-rise buildings provided with friction dampers is investigated. The steel buildings are modelled as shear-type structures and the investigation involved modelling of the structures of varying heights ranging from five storeys to twenty storeys, in steps of five storeys, subjected to real earthquake ground motions. Three basic types of structures considered in the study are: moment resisting frame (MRF), braced frame (BF), and friction damper frame (FDF). Mathematical modelling of the friction dampers involved simulation of the two distinct phases namely, the stick phase and the slip phase. Dynamic time history analyses are carried out to study the variation of the top floor acceleration, top floor displacement, storey shear, and base-shear. Further, energy plots are obtained to investigate the energy dissipation by the friction dampers. It is seen that substantial earthquake response reduction is achieved with the provision of the friction dampers in the mid-rise and high-rise buildings. The provision of the friction dampers always reduces the base-shear. It is also seen from the fast Fourier transform (FFT) of the top floor acceleration that there is substantial reduction in the peak response; however, the higher frequency content in the response has increased. For the structures considered, the top floor displacements are lesser in the FDF than in the MRF; however, the top floor displacements are marginally larger in the FDF than in the BF.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.385-397
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• 2023

This study presents an experiment and analysis to compare the seismic behavior of full-scale reinforced concrete beam-column joint strengthened by prestressed steel strips, externally bonded steel plate, and CFRP sheets. For experimental investigation, five specimens, including one joint without any retrofitting, one joint retrofitted by externally bonded steel plate, one joint retrofitted by CFRP sheets, and two joints retrofitted by prestressed steel strips, were tested under cyclic-reserve loading. The failure mode, strain response, shear deformation, hysteresis behavior, energy dissipation capacity, stiffness degradation and damage indexes of all specimens were analyzed according to experimental study. It was found that prestressed steel strips, steel plate and CFRP sheets improved shear resistance, energy dissipation capacity, stiffness degradation behavior and reduced the shear deformation of the joint core area, as well as changed the failure pattern of the specimen, which led to the failure mode changed from the combination of flexural failure of beams and shear failure of joints core to the flexural failure of beams. In addition, the beam-column joint retrofitted by steel plate exhibited a high bearing capacity, energy consumption capacity and low damage index compared with the joint strengthened by prestressed steel strip, and the prestressed steel strips reinforced joint showed a high strength, energy dissipation capacity and low shear deformation, stirrups strains and damage index compared to the CFRP reinforced joint, which indicated that the frame joints strengthened with steel plate exhibited the most excellent seismic behavior, followed by the prestressed steel strips.

• Structural Engineering and Mechanics
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• v.36 no.1
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• pp.57-78
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• 2010

A novel flexibility-based 1D element that captures the material nonlinearity and second order P-$\Delta$ effects within a reinforced concrete frame member is developed. The formulation is developed for 2D planar frames in the modified fiber element framework but can readily be extended to 3D cases. The nonlinear behavior of concrete including cracking and crushing is taken into account through a modified hypo-elastic model. A parabolic and a constant shear stress distribution are used at section level to couple the normal and tangential tractions at material level. The lack of objectivity due to softening of concrete is addressed and objectivity of the response at the material level is attained by using a technique derived from the crack band approach. Finally the efficiency and accuracy of the formulation is compared with experimental results and is demonstrated by some numerical examples.

• Earthquakes and Structures
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• v.7 no.6
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• pp.937-953
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• 2014

A semi-active control platform comprising the mechanical model of magnetorheological (MR) dampers, the bang-bang control law and damage material models is developed, and the simulation method of steel plate shear wall (SPSW) and optimization method for capacity design of MR dampers are proposed. A 15-story steel frame-SPSW structure is analyzed to evaluate the seismic performance of nonlinear semi-active controlled structures with optimal designed MR dampers, results indicate that the control platform and simulation method are stable and fast, and the damage accumulation effects of uncontrolled structure are largely reduced, and the seismic performance of controlled structures has been improved.

• Computers and Concrete
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• v.12 no.4
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• pp.393-411
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• 2013

In the analysis and design of reinforced concrete frames beam-column joints are sometimes assumed as rigid. This simplifying assumption can be unsafe because it is likely to affect the distributions of internal forces and moments, reduce drift and increase the overall load-carrying capacity of the frame. This study is concerned with the relevance of shear deformation of beam-column joints, in particular of exterior ones, on the quasi-static behavior of regular reinforced concrete sway frames. The included parametric studies of a simple sub-frame model reveal that the quasi-static monotonic behavior of unbraced regular reinforced concrete frames is prone to be significantly affected by the deformation of beam-column joints.

• Steel and Composite Structures
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• v.19 no.2
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• pp.467-484
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• 2015

Seismic performances of dual steel moment-resisting frames with mixed use of rigid and semi-rigid connections were investigated to control of the base shear, story drifts and the ductility demand of the elements. To this end, nonlinear seismic responses of three groups of frames with three, eight and fifteen story were evaluated. These frames with rigid, semi-rigid and combined configuration of rigid and semi-rigid connections were analyzed under five earthquake records and their responses were compared in ultimate limit state of rigid frame. This study showed that in all frames, it could be found a state of semi-rigidity and connections configuration which behaved better than rigid frame, with consideration of the base shear and story drifts criterion. Finally, some criteria were suggested to locate the best place of the semi-rigid connections for improvement of the seismic performance of steel moment-resisting frames.

• Earthquakes and Structures
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• v.16 no.4
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• pp.425-436
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• 2019

Successive ground motions having short time intervals have occurred in many earthquakes so far. It is necessary to investigate the effects of this phenomenon on different types of structures and to take these effects into consideration while designing or retrofitting structures. The effects of seismic sequences on the structures with combined reinforced concrete shear wall and moment resisting frame system have not been investigated in details yet. This paper has tried to analyse the seismic performance of structures with such structural systems subjected to mainshock-aftershock sequences. The effects of the seismic sequences on the investigated models are evaluated by strong measures such as IDA capacity and fragility and vulnerability curves. The results of this study show that the seismic sequences have a significant effect on the investigated models, which necessitates considering this effect on designing, retrofitting, decision making, and taking precautions.

• Structural Engineering and Mechanics
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• v.72 no.4
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• pp.443-454
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• 2019

In order to reduce the residual drift of a structure in structural engineering field, a combined structural system (dual) consisting of steel buckling-restrained braced frame (BRBF) along with shear wall is proposed. In this paper, BRBFs are used with special reinforced concrete shear walls as combined systems. Some prototype models of the proposed combined systems as well as steel BRBF-only systems (without walls) are designed according to the code recommendations. Then, the nonlinear model of the systems is prepared using fiber elements for the reinforced concrete wall and appropriate elements for the BRBs. Seismic responses of the combined systems subjected to ground motions at maximum considered earthquake level are investigated and compared to those obtained from BRBFs. Results showed that the maximum residual inter-story drift from the combined systems is, on average, less than half of the corresponding value of the BRBFs. In this research, mean of absolute values of the maximum inter-story drift ratio demand obtained from combined systems is less than the 3% limitation, while this criterion has not been fulfilled by BRBF systems.