• Steel and Composite Structures
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• v.27 no.6
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• pp.761-775
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• 2018

In the present work, the recently developed non-polynomial shear deformation theories are assessed for thermo-mechanical response characteristics of laminated composite plates. The applicability and accuracy of these theories for static, buckling and free vibration responses were ascertained in the recent past by several authors. However, the assessment of these theories for thermo-mechanical analysis of the laminated composite structures is still to be ascertained. The response characteristics are investigated in linear and non-linear thermal gradient and also in the presence and absence of mechanical transverse loads. The laminated composite plates are modelled using recently developed six shear deformation theories involving different shear strain functions. The principle of virtual work is used to develop the governing system of equations. The Navier type closed form solution is adopted to yield the exact solution of the developed equation for simply supported cross ply laminated plates. The thermo-mechanical response characteristics due to these six different theories are obtained and compared with the existing results.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.407-420
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• 2019

In the present work, an attempt is made to explore the effects of shear in-plane preload on the wave propagation response of small-scale plates containing nanofibers. The small-scale system is assumed to be embedded in an elastic matrix. The nonlocal elasticity is utilized in order to develop a size-dependent model of plates. The proposed plate model is able to describe both nanofiber effects and the influences of being at small-scales on the wave propagation response. The size-dependent differential equations are derived for motions along all directions. The size-dependent coupled equations are solved analytically to obtain the phase and group velocities of the small-scale plate under a shear in-plane preload. The effects of this shear preload in conjunction with nanofiber and size effects as well as the influences of the elastic matrix on the wave propagation response are analyzed in detail.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.48-51
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• 2004

This paper is to study the response of flat plate slab-column connections consisting of various types of shear reinforcement and steel plate subjected to gravity loadings, mainly punching shear forces using the non-destructive testing, spectral analysis of surface waves and structural experiments. The base specimen failed due to punching shear generated from the gravity. The three other types of slab shear reinforcement and steel plate showed effective in resisting punching shear for these types of connections under gravity loading. This study has focused in evaluating the velocity response of a Surface wave during the early age as the poured concrete specimens have been hardened, the possibility of damage detection in the slab-column connection and the relationship between the punching shear forces and the surface wave velocities under the condition that the punching shear forces had gradually increased until the flat plate slab in slab-column connection had been failed.

• Computers and Concrete
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• v.10 no.4
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• pp.419-434
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• 2012

This paper presents a finite element (FE) model for predicting the nonlinear response and behavior of a reinforced concrete T-beam deficient in shear under cyclic loading. Cracking loads, failure loads, response hysteresis envelopes and crack patterns were used as bench mark for comparison between experimental and FE results. A parametric study was carried out to predict the optimum combination of the open and close crack shear transfer coefficients (${\beta}_t$ and ${\beta}_c$) of the constitutive material model for concrete. It is concluded that when both shear transfer coefficients are equal to 0.2 the FE results gave the best correlation with the experimental results. The results were also verified on a rectangular shear deficient beam (R-beam) tested under cyclic loading and it is concluded that the variation of section geometry has no effect on the optimum choice of the values of shear transfer coefficients of 0.2. In addition, a parametric study based on the variation of concrete compressive strength, was carried out on the T-beam and it is observed that the variation of concrete compressive strength has little effect on the deflection. Further conclusions and observations were also drawn.

• Journal of the Earthquake Engineering Society of Korea
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• v.25 no.3
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• pp.129-135
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• 2021

After the manual shutdown of the Wolseong nuclear power plant due to an earthquake in Gyeongju in 2016, anxiety about the earthquake safety of nuclear power plants has become a major social issue. The shear wall structure used as a major structural element in nuclear power plants is widely used as a major structural member because of its high resistance to horizontal loads such as earthquakes. However, due to the complexity of the structure, it is challenging to predict the dynamic characteristics of the structure. In this study, a three-story shear wall structure is fabricated, and the in-structure response characteristics of the shear wall structure are evaluated through shaking table tests. The test is performed using the Gyeongju earthquake that occurred in 2016, and the response characteristics due to the domestic earthquake are evaluated.

• Earthquakes and Structures
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• v.22 no.2
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• pp.109-120
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• 2022

Older or damaged structures can require significant retrofit to ensure they perform well in subsequent earthquakes. Supplemental damping devices are used to achieve this goal, but increase base shear forces, foundation demand, and cost. Displacement reduction without increasing base shear is possible using novel semi-active and recently-created passive devices, which offer energy dissipation in selected quadrants of the force-displacement response. Combining these devices with large, strictly passive energy dissipation devices can offer greater, yet customized response reductions. Supplemental damping to reduce response without increasing base shear enables a net-zero base shear approach. This study evaluates this concept using two incremental dynamic analyses (IDAs) to show displacement reductions up to 40% without increasing base shear, more than would be achieved for either device alone, significantly reducing the risk of response exceeding the unaltered structural case. IDA results lead to direct calculation of reductions in risk and annualized economic cost for adding these devices using this net-zero concept, thus quantifying the trade-off. The overall device assessment and risk analysis method presented provides a generalizable proof-of-concept approach, and provides a framework for assessing the impact and economic cost-benefit of using modern supplemental energy dissipation devices.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2885-2889
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• 2007

In this study, the effect of particle aggregation on dynamic response time of Electrorheological (ER) fluid is investigated. The particle aggregation time is defined as the time interval between the application of the field and the formation of the first chain bridging the two electrodes. The dynamic response times of an ER fluid sheared between two concentric cylinders have been obtained under two different experimental conditions: the one is that the electric field is induced before shearing, and the other is that the electric field is induced after shearing. From the difference between two response times, the particle aggregation times are determined under various electric fields and shear rates. The experimental results show that the aggregation rate is decreased with an increase of shear rate, while electric field has little effect on it. Therefore, it is verified that the hydrodynamic force hinders the formation of chain-like structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.2
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• pp.73-78
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• 2014

In this paper, the stochastic 1D site response analysis method using Monte Carlo simulation and considering thespatial variation of shear wave velocity profile isproposed. To consider thespatial variation of shear wave velocity profile for 1D site response analysis, the proposed method generates random shear wave velocity profiles representing the target site, and Monte Carlo simulation is used to calculate theprobability distribution of the site response analysis results such as thepeak ground acceleration. Through the field application, The applicability of the proposed method is verified through field application.

• Steel and Composite Structures
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• v.6 no.3
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• pp.183-202
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• 2006

The behavior of steel-concrete composite beams is strongly influenced by the type of shear connection between the steel beam and the concrete slab. For accurate analytical predictions, the structural model must account for the interlayer slip between these two components. This paper focuses on a procedure for response sensitivity analysis using state-of-the-art finite elements for composite beams with deformable shear connection. Monotonic and cyclic loading cases are considered. Realistic cyclic uniaxial constitutive laws are adopted for the steel and concrete materials as well as for the shear connection. The finite element response sensitivity analysis is performed according to the Direct Differentiation Method (DDM); its analytical derivation and computer implementation are validated through Forward Finite Difference (FFD) analysis. Sensitivity analysis results are used to gain insight into the effect and relative importance of the various material parameters in regards to the nonlinear monotonic and cyclic response of continuous composite beams, which are commonly used in bridge construction.

• Steel and Composite Structures
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• v.48 no.3
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• pp.353-365
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• 2023

Shape memory alloys (SMAs) have emerged as a novel functional material that is being increasingly applied in diverse fields including medical, aeronautical and structural engineering to be used in the active, passive and semi-active structural control devices. This paper is mainly aimed at evaluating the ductility and response modification factor of the steel plate shear wall (SPSW) frames with and without the Ni-Ti shape memory alloys. To this end, different configurations were utilized, in which the walls were used in the first, third, middle, and all stories. The models were numerically analyzed using OpenSees Software. The obtained results indicate that improving the shape memory properties of alloys can greatly enhance the ductility and response modification factor. Furthermore, the model whose first and third stories are equipped with the SMA shear wall was found to be 290% more ductile, with a greater response modification factor compared to the unequipped frame.