• Earthquakes and Structures
• /
• 제13권3호
• /
• pp.241-253
• /
• 2017

In this paper, dynamic response of the horizontal nanofiber reinforced polymer (NFRP) strengthened concrete beam subjected to seismic ground excitation is investigated. The concrete beam is modeled using hyperbolic shear deformation beam theory (HSDBT) and the mathematical formulation is applied to determine the governing equations of the structure. Distribution type and agglomeration effects of carbon nanofibers are considered by Mori-Tanaka model. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle (virtual work method), the governing equations are derived. To obtain the dynamic response of the structure, harmonic differential quadrature method (HDQM) along with Newmark method is applied. The aim of this study is to investigate the effect of NFRP layer, geometrical parameters of beam, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure up to 91 percent. In addition, using nanofibers as reinforcement leads a 35 percent reduction in the maximum dynamic displacement of the structure.

• Korean Journal of Geomatics
• /
• 제5권1호
• /
• pp.51-58
• /
• 2005

GPS measurements from Feb. 2002 through Mar. 2004 were used to estimate recent crustal movement across the Lai Chau - Dien Bien fault system in North-West Vietnam. Four GPS campaign data were processed and combined with appropriate constraints using automatic GAMIT/GLOBK run in order to estimate ITRF2000 coordinates, local horizontal velocity and extensive/compressive strain rates. ITRF2000 velocities are consistent with east-southeastward movement of Sundaland i.e. Indochina. Local velocities show not much left-lateral strike-slip of the fault system and derived strain rates are insignificant from zero at $95\%$ confidence.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
• /
• pp.97-102
• /
• 1992

To predict the shear strength of low - rise reinforced concrete shear walls with boundary elements, truss model theory considering the Vecchio - Collins stress - strain curve for softened concrete is applied. The model transforms cracked shear walls with a truss which consists of vertical bar. horizontal bar and diagonal concrete strut, and is based on equilibrium and compatibility conditions among three truss components, as well as stress - strain relationship considered for softening in diagonal concrete strut. In barbell specimens(M/VD = 0.75. fc = 420 kg/$\textrm{cm}^2$), the ratio of experimental to analytical maximum shear strength was within 0.83 ν$_{exp}$. / ν$_{cal}$. 1.25 with a relatively good agreement. As a result, the truss model was observed to be capable of predicting the maximum shear strength wi th a reasonable accuracy.acy.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
• /
• pp.349-352
• /
• 2004

In this study, a strut-and-tie models for the coupling beam based on deformations are presented. To design shear-dominated R/C coupling beams, it is important to consider shear strength deterioration with required deformations. This study proposes the method of estimating shear strength of the reinforced concrete coupling beams. The proposed method determines the strain states from target displacements based on the nonlinear truss analysis. The estimated horizontal strain of beam is then used in calculating the strength of the diagonal strut with compatibility conditions. The deterioration of shear strength of the coupling beam depends on the strength degradation of struts due to plastic deformations.

• Earthquakes and Structures
• /
• 제13권2호
• /
• pp.137-150
• /
• 2017

This paper focuses on the post-earthquake serviceability of steel arch bridges installed with three types of seismic dampers suffered mainshock-aftershock sequences. Two post-earthquake serviceability verification methods for the steel arch bridges are compared. The energy-absorbing properties of three types of seismic dampers, including the buckling restrained brace, the shear panel damper and the shape memory alloy damper, are investigated under major earthquakes. Repeated earthquakes are applied to the steel arch bridges to examine the influence of the aftershocks to the structures with and without dampers. The relative displacement is proposed for the horizontal transverse components in such complicated structures. Results indicate that the strain-based verification method is more conservative than the displacement-base verification method in evaluating the post-earthquake serviceability of structures and the seismic performance of the retrofitted structure is significantly improved.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
• /
• pp.481-488
• /
• 1998

Elastomeric bearing is used as one of the most useful way for isolation structures, because the horizontal stiffness is much lower than the vertical stiffness. In the design criteria of Elastomeric bearing, the stability of the bearings is evaluated by shear strain due to compression, lateral displacement, and rotation. The question how soft rubber can sustain heavy structure is now able to be solved by Ultimate capacity test of Laminated Elastomeric Bearings, which results 1,200kg/$\textrm{cm}^2$ of the max. compressive stress and this shows what a sufficient safety factor Elastomeric bearing has !

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
• /
• pp.52-57
• /
• 1992

The purpose of this study is that to develop computer program, which is about to analy size nonlinear behaviour of elastic framed structures include to geometric & material nonlineality, and to formulate between stress-strain relationship. In order to examplity the efficiency of this program, a few analytical results have been obtained on : (1) nonlinear behaviour of beam which is subject to vertical force (2) nonlinear behaviour of portal frame which is subject to vertical & horizontal force.

• Computational Structural Engineering : An International Journal
• /
• 제3권1호
• /
• pp.9-17
• /
• 2003

This paper aims at investigating the damage process of steel members leading to the failure under strong repeated loading, proposing the damage index using various factors related to the damage, and developing the analysis method for evaluating the damage state. Cantilever-type steel members were analyzed under uniaxial load and combined with a constant axial load, considering a horizontal displacement history. In analyzing the models, loading patterns and steel types (SS400, SM570, Posten80) were considered as main parameters. From the analysis results, the effects of parameter on the failures mode, the deformation capacity, the damage process are also discussed. Each failure process was compared as steel types. Consequently, the failure of steel members under strong repeated loading was determined by loading. Especially it was seen that the state of the failure is closely related to the local strain.

• 한국임상수의학회지
• /
• 제36권3호
• /
• pp.155-158
• /
• 2019

Morphologic changes or functional impairments of the papillary muscle (PM) can influence mitral valve competence. The purpose of this study was to investigate PM size and contractile function using two-dimensional and color tissue Doppler echocardiography in normal dogs. 35 unsedated Beagle dogs without cardiovascular disease were examined. The vertical (VD) and horizontal diameter (HD) of the posterior and anterior PM was measured at end-diastole, and compared with the thickness of the left ventricular posterior wall (LVPWd). Longitudinal systolic movement of the PM was quantified as myocardial velocity and strain using tissue Doppler. The VD, HD, and ratios (VD/LVPWd, HD/LVPWd, VD/HD) were significantly greater in the posterior than anterior PM (P < 0.001). The VD and HD of posterior PM and the HD of anterior PM were significantly correlated with LVPWd (r = 0.47, 0.44, and 0.42, respectively). Body weight was significantly correlated with VD of posterior PM (r = 0.37). The peak systolic tissue velocity of the PM was $4.93{\pm}1.25cm/sec$ and peak strain was $-30.83{\pm}11.92%$. PM size and systolic function can be quantitatively assessed using two-dimensional and tissue Doppler. The establishment of these objective PM measurements may be useful to evaluate morphological and functional abnormalities of the canine PM.

• Geomechanics and Engineering
• /
• 제24권1호
• /
• pp.67-79
• /
• 2021

The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.