• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.577-580
• /
• 2004

Recently, DFRCCs (Ductile Fiber Reinforced Cementitious Composites), materials with remarkable ductility when compared to ordinary fiber-reinforced concrete (FRC), have been developed and studied actively in the US, Japan, and many European countries. The transformation of failure behavior from brittle to ductile is achieved by incorporating with fracture mechanics concept especially micro-mechanical models approach of cementitious composite materials in manufacturing ordinary fiber-reinforced composites. The purpose of this study is to accurately understand the shear behavior of DFRCC repaired RC beams. Using a four-point bending test, the shear strengths and shear stress-deflection relations of DFRCC repaired RC specimens are obtained. The results show that DFRCC can be effectively used for repairing materials for concrete structures.

• Journal of KSNVE
• /
• v.10 no.1
• /
• pp.57-63
• /
• 2000

On the basis of the concept of strain energy-weighted dissipation, an enhanced model for predicting damping in laminates is presented. In this model, the influence of transverse shear on $90^{\circ}$ laminates has been included with those of in-plane stresses on beam. Also, an experimental damping measurement is conducted with changing the length and the thickness of laminated beam specimen for confirmation of the model prediction. The theoretical predictions in $90^{\circ}$laminates were reasonably compared with experimental data. The transverse shear reveals to have an influence on the damping, behavior in $90^{\circ}$ laminates.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.09a
• /
• pp.180-187
• /
• 2003

The purpose of this study is to investigate the seismic behavior of reinforced concrete shear wall subjected to earthquake motions. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), was used for the analysis of reinforced concrete structures. A 4-node flat shell element with drilling rotational stiffness is used for spatial discretization. The layered approach is used to discretize behavior of concrete and reinforcement through the thickness. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. Solution of the equations of motion is obtained by numerical integration using Hither-Hughes-Taylor(HHT) algorithm. The proposed numerical method for the seismic analysis of reinforced concrete shear wall is verified by comparison of analysis results with reliable experimental results.

• Steel and Composite Structures
• /
• v.33 no.4
• /
• pp.551-568
• /
• 2019

This proposed project presents the bi-axial and uni-axial stability behavior of laminated composite plates based on an original three variable "refined" plate theory. The important "novelty" of this theory is that besides the inclusion of a cubic distribution of transverse shear deformations across the thickness of the structure, it treats only three variables such as conventional plate theory (CPT) instead five as in the well-known theory of "first shear deformation" (FSDT) and theory of "higher order shear deformation" (HSDT). A "shear correction coefficient" is therefore not employed in the current formulation. The computed results are compared with those of the CPT, FSDT and exact 3D elasticity theory. Good agreement is demonstrated and proved for the present results with those of "HSDT" and elasticity theory.

• Earthquakes and Structures
• /
• v.16 no.2
• /
• pp.177-183
• /
• 2019

In this paper, a new refined hyperbolic shear deformation beam theory for the bending analysis of functionally graded beam is presented. The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the functionally graded beam without using shear correction factors. In addition, the effect of different micromechanical models on the bending response of these beams is studied. Various micromechanical models are used to evaluate the mechanical characteristics of the FG beams whose properties vary continuously across the thickness according to a simple power law. Based on the present theory, the equilibrium equations are derived from the principle of virtual work. Navier type solution method was used to obtain displacement and stresses, and the numerical results are compared with those available in the literature. A detailed parametric study is presented to show the effect of different micromechanical models on the flexural response of a simply supported FG beams.

• Steel and Composite Structures
• /
• v.41 no.6
• /
• pp.851-860
• /
• 2021

In this paper, a new approach of interface stress analysis in steel beam strengthened by porous FGM (Functionally Graded Materials) is presented to calculate the shear stress in the hybrid steel beam and loaded by a uniformly distributed load. The results show that there exists a high concentration of shear stress at the ends of the imperfect FGM, which might result in premature failure of the strengthening scheme at these locations. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as the rigidity of FGM plate (degree of homogeneity), the porosity index of FGM and the thickness of adhesive all were found to have a marked effect on the magnitude of maximum shear stress in the FGM member. we can conclude that the new approach is general in nature and may be applicable to all kinds of materials.

• Geomechanics and Engineering
• /
• v.33 no.5
• /
• pp.427-437
• /
• 2023

The objective of this work is to study the wave propagation of an FGM plate via a new integral inverse shear model with temperature-dependent material properties. In this contribution, a new model based on a high-order theory field of displacement is included by introducing indeterminate integral variables and inverse co-tangential functions for the presentation of shear stress. The temperature-dependent properties of the FGM plate are assumed mixture of metal and ceramic, and its properties change by the power functions of the thickness of the plate. By applying Hamilton's principle, general formulas of wave propagation were obtained to plot the phase velocity curves and wave modes of the FGM plate with simply supported edges. The effects of the temperature and volume fraction by distributions on wave propagation of the FGM plate are investigated in detail. The results of the dispersion and the phase velocity curves of the propagation wave in the functionally graded plate are compared with previous research.

• Steel and Composite Structures
• /
• v.48 no.2
• /
• pp.145-161
• /
• 2023

This study investigates the influences of porosity on the stability of the orthotropic laminated plates under uniaxial and biaxial loadings based on the hyperbolic shear deformation theory. Three different porosity distribution are considered with three specific functions through the plate thickness. The stability equations of porous orthotropic laminated plates are derived by the virtual work principle. Applying the Galerkin method to partial differential equations, the critical buckling load relation of porous orthotropic laminated plates is obtained. After validating the accuracy of the proposed formulation in accordance with the available literature, a parametric analysis is performed to observe the sensitivity of the critical buckling load to shear deformation, porosity, orthotropy, loading factor, and different geometric properties.

• Tribology and Lubricants
• /
• v.11 no.5
• /
• pp.71-77
• /
• 1995

The capacitance technique was used to measure the minimum oil film thickness in engine bearing and the central oil film thickness between cam and tappet. This method is based on the measurement of total capacitance of oil film. For the measurement of the oil film thickness between cam and tappet, two surfaces were assumed to be flat and parallel within the Hertzian region and all the measured capacitance originated from this region. Shear rates from the measured minimum oil film thickness are over 10$^{6}$ sec$^{-1}$ in the greater part in both two cases. The minimum oil film thickness in engine bearing is larger than the surface roughness. Between cam and tappet it is mostly smaller than the surface roughness. In spite of the awkward restriction of the reliability of measured oil film thickness, it was known that the capacitance technique makes it possible to measure the oil film thickness in elastohydrodynamic and mixed lubrication regimes as well as in hydrodynamic regime. Therefore, it is also possible to classify the lubrication regimes based on the oil film thickness.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.285-292
• /
• 1999

The cyclic plate load test were peformed to determine the behavior of reinforced soft ground with multiple layers of geogrid. Five series of test were conducted with varying the soil profile conditions which including the ground level, type of soil, and the thickness of each soil layer. The plate load test equipment was slightly modified to apply the cyclic load. Based on the cyclic plate load test results, the bearing capacity ratio(BCR), subbase modules, shear modules, the elastic rebound ratio, and reinforcing parameters are presented.