• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.117-120
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• 2008

The bridge bearings are devices absorbing the displacements of the superstructure. KS F 4420 relative to the design of elastomeric bearings in Korea allows shear deformation up to 70% of total rubber height. For the elastomeric bearings to fulfill their shear function required in the design, the stability of allowable shear strain of elastomeric bearings relative to the shear failure should be guaranteed. Moreover considering the possibility that elastomeric bearings are applied to the seismic design together with isolation devices, elastomeric bearings is supposed to display higher shear performance. In this paper ultimate shear performance tests were performed. The measured ultimate shear strains were over 200%. Therefore an allowable shear strain provision becomes safe. But elastomeric bearings expected to show their performance in one united body reveled the separation of components near 200% shear strain. These separation in elastomeric bearing can cause unexpected impact or concentrated stress to bridge system considering to application of seismic design. Therefore provision relevant to separation problem is necessary.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.911-922
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• 2005

A theoretical study was performed to investigate the behavioral chracteristics and shear strength of fiber reinforced concrete slender beams. In the fiber reinforced concrete beam, the shear force applied to a cross section of the beam was resisted by both compressive zone and tensile zone. The shear capacity of the compressive zone was defined addressing the interaction with the normal stresses developed by the flexural moment in the cross section. The shear capacity of the tensile zone was defined addressing the post-cracking tensile strength of fiber reinforced concrete. Since the magnitude and distribution of the normal stresses vary according to the flexural deformation of the beam, the shear capacity of the beam was defined as a function of the flexural deformation of the beam. The shear strength of the beam and the location of the critical section were determined at the intersection between the shear capacity and shear demand curves. The proposed method was developed as a unified shear design method which is applicable to conventional reinforced concrete as well as fiber reinforced concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1C
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• pp.53-62
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• 2008

A constitutive model, which can simulate the effect of principal stress rotation associated with direct simple shear test, is proposed in this study. The model is based on two mobilized planes. The plastic strains occur from the two mobilized planes, and depend on stress state, and they are added. The first plane is a plane of maximum shear stress, which rotates about the horizontal axis, and the second plane is a horizontal plane which is spatially fixed. The second plane is used to consider the effect of principal stress rotation on simple shear tests under different stress states. The soil skeleton behavior observed in drained simple shear tests is captured in the model. This constitutive model is incorporated into the dynamic coupled stress-flow finite difference program FLAC. The model is first calibrated with drained simple shear tests on loose Fraser River sand. The measured shear stress and volume change are partially induced by principal stress rotation and compared with model calculations. The model is verified by comparing predicted and measured settlements due to rigid footing resting on loose sands. Settlements predicted by the proposed model were very similar to measured settlements. Mohr-Coulomb model can not consider the effect of principal stress rotation and its prediction was only 20% of measured settlements.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.575-584
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• 2006

In this paper, a shear-flexible finite element model is developed for the buckling analysis of axially loaded, thin-walled composite I-beams. Based on an orthogonal Cartesian coordinate system, the displacement fields are defined using the first-order shear-deformable beam theory. The derived element takes into account flexural shear deformation and torsional warping deformation. Three different types of beam elements, namely, the two-noded, three-noded, and four-noded beam elements, were developed to solve the governing equations. An inverse iteration with shift eigenvalue solution was used to solve the resulting linearized buckling problem. A parametric study was conducted to show the importance of shear flexibility and fiber orientation on the buckling behavior of thin-walled composite beams. A good agreement was obtained among the proposed shear-flexible model, other results available in literature, and the finite element solution.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.49-60
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• 2016

Soil failure is initiated and preceded by forming and progressing of shear band, defined as the localization of deformation into thin zones of soil mass. To understand the failure mechanism of normally consolidated cohesive soil, the spatial distribution and evolution of deformation within the entire specimen need to be evaluated. In this study, vertical compression tests under plane strain condition were performed on reconstituted kaolinite specimens, while capturing digital images of the specimen at regular intervals during shearing. Overall stress-strain behavior from initial to post peak has been analyzed together with spatial distributions of deformations and shear band characteristics from digital images at 4 stages.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.36-43
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• 2006

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.505-512
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• 2012

In this paper, an efficient yet accurate method for the thermal stress analysis using a first order shear deformation theory(FSDT) is presented. The main objective herein is to systematically modify transverse shear strain energy through the mixed variational theorem(MVT). In the mixed formulation, independent transverse shear stresses are taken from the efficient higher-order zigzag plate theory, and the in-plane displacements are assumed to be those of the FSDT. Moreover, a smooth parabolic distribution through the thickness is assumed in the transverse normal displacement field in order to consider a transverse normal deformation. The resulting strain energy expression is referred to as an enhanced first order shear deformation theory, which is obtained via the mixed variational theorem with transverse normal deformation effect(EFSDTM_TN). The EFSDTM_TN has the same computational advantage as the FSDT_TN(FSDT with transverse normal deformation effect) does, which allows us to improve the through-the-thickness distributions of displacements and stresses via the recovery procedure. The thermal stresses obtained by the present theory are compared with those of the FSDT_TN and three-dimensional elasticity.

• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.295-303
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• 2004

In this paper, an improved four-node Reissner-Mindlin plate-bending element with enhanced assumed strain field is presented for the analysis of isotropic and laminated composite plates. To avoid the shear locking and spurious zero energy modes, the transverse shear behavior is improved by the addition of a new enhanced shear strain based on the incompatible displacement mode approach and bubble function. The "standard" enhanced strain fields (Andelfinger and Ramm, 1993) are also employed to improve the in-plane behaviors of the plate elements. The four-node quadrilateral element derived using the first-order shear deformation theory is designated as "14EASP". Several applications are investigated to assess the features and the performances of the proposed element. The results are compared with other finite element solutions and analytical solutions. Numerical examples show that the element is stable, invariant, passes the patch test, and yields good results especially in highly distorted regimes.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.33-39
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• 2008

Dual-function interferometer is an interferometer that has all features of ESPI (electronic speckle pattern interferometry) and shearography in one interferometer setup. The deformatiou of an object is directly obtained by ESPI while the slope of the deformation of an object is obtained by shearography. If the result of shearography is divided by shearing amount and integrated by numerical analyzing, then finally the reconstructed deformation of an object that is the same as the results directly obtained by ESPI can be measured by shearography. In this study, rubber and alruminum plates are used as specimen and its out-of-plane deformation is measured by ESPI and shearography setup of the dual-function interferometer. Each of the results obtained by ESPI and shearography is compared by using numerical integration to the result of shearography. From this study, it is confirmed that the reconstructed deformation results obtained by numerical integration good agree with the results obtained by ESPI.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.197-200
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• 2008

An analytical model for predicting the shear strength of prestressed concrete beams was developed, applying the previously proposed strain-based shear strength model. In flexure-compression member without shear reinforcement, compression zone of intact concrete primarily resist to the shear force rather than tension zone. The shear capacity of concrete at the compression zone was defined based on the material failure criteria. The shear capacity of the compression zone was evaluated along the inclined failure surface considering interaction with the normal stress. Since the distribution of normal stress varies due to the flexural deformation of member, the shear capacity was defined as a function of the flexural deformation. Finally, the shear strength was determined at the intersection of the shear capacity curve and the shear demand curve. As a result of the comparisons to prior test data, the proposed model accurately predicted the shear strength of specimens.