• Smart Structures and Systems
• /
• v.14 no.5
• /
• pp.883-900
• /
• 2014

Shape memory alloys (SMA) can dissipate energy through hysteresis cycles without significant residual deformation. This paper describes the fabrication and testing of copper-based SMA hourglass-shaped plates for use in energy dissipation devices and the development of a numerical model to reproduce the experiments. The plates were tested under cyclic flexural deformations, showing stable hysteresis cycles without strength degradation. A detailed nonlinear numerical model was developed and validated with the experimental data, using as input the constitutive relationship for the material determined from cyclic tests of material coupons under tension loading. The model adequately reproduces the experimental results. The study is focused on the exploitation of SMA in the martensite phase.

• Structural Engineering and Mechanics
• /
• v.34 no.3
• /
• pp.301-317
• /
• 2010

This paper studies the reliability of an analytical tool for predicting the lateral load-deformation response of RC columns while subjected to lateral cyclic displacements and axial load. The analytical tool in this study is based on a fiber element model implemented into the program DRAIN-2DX (fiber element). The response of RC column under cyclic displacement is defined by the behavior of concrete, and reinforcing steel under general reversed-cyclic loading. A tri-linear stress-strain relationship for the cyclic behavior of steel is proposed and the improvement in the analytical results is studied. This study only considers the behavior of columns with flexural dominant mode of failure. It is concluded that with the implementation of appropriate constitutive material models, the described analytical tools can predict the response of the columns with reasonable accuracy when compared to experimental data.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.362-365
• /
• 2006

This paper presents a model for evaluating the contribution by arch action to shear resistance in shear-critical RC beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, The behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. The compatibility condition of the shear deformation that deviates from Bernoulli bending plane is formulated utilizing the smeared truss idealization with an inclined compression chord. From this shear compatibility condition in a beam, the shear contribution by the arch action is numerically decoupled.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.233-234
• /
• 2010

Using an expansion admixture can reduce an initial shrinkage crack and improve a prestress. Therefore, this paper presents the results of a study performed to evaluate this deformation and obtain a better understanding of the behavior of SHCC using an expansion admixture. To evaluate a performance of SHCC using an expansion admixture was tested a drying shrinkage, compressive strength, flexural strength, and tensile strength.

• Computers and Concrete
• /
• v.5 no.1
• /
• pp.37-60
• /
• 2008

Structural health monitoring of existing infrastructure is currently an important field of research, where elaborate experimental programs and advanced analytical methods are used in identifying the current state of health of critical and important structures. The paper outlines two methods of system identification of beam-like reinforced concrete structures representing bridges, through static measurements, in a distributed damage scenario. The first one is similar to the stiffness method, re-cast and the second one to flexibility method. A least square error (LSE) based solution method is used for the estimation of flexural rigidities and damages of simply supported, cantilever and propped cantilever beam from the measured deformation values. The performance of both methods in the presence of measurement errors is demonstrated. An experiment on an un-symmetrically damaged simply supported reinforced concrete beam is used to validate the developed method. A method for damage prognosis is demonstrated using a generalized, indeterminate, propped cantilever beam.

• Proceedings of the KSR Conference
• /
• 2001.10a
• /
• pp.534-539
• /
• 2001

This paper presents the critical speed analysis of geogrid-reinforced rail roadbeds on soft soil. A rail roadbed on soft ground must be designed to avoid intolerable stress in the underlying soil and to give sufficient support for the rail system. At high speeds, the deformation of rail systems will gain dynamic amplification, and reach excessive values as a certain speed, here termed critical speed is approached. The elastic Winkler foundation model was used to predict the critical speed of geogrid-reinforced rail roadbeds on soft soil and the model properties were determined by the in-situ cyclic plate load test. Based on the parametric study of elastic beam on Winkler foundation model, the critical speed increase with the increase of the flexural risidity of subgrade EI and the stiffness coefficient of Winkler foundation k. From the in-situ cyclic load tests and analysis of elastic beam on Winkler foundation model, the critical speed increase with increase in number of reinforced layer and non-dimensional value for depth of first geogrid layers and the thickness of reinforced rail roadbed u/d.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.04a
• /
• pp.334-339
• /
• 1996

본 연구의 목적은 불확실성이 내포되어 있는 콘크리트 구조물을 신뢰성 이론에 근거한 보통강도, 고강도 콘크리트에서의 휨모멘트-곡률관계와 하중변위관계를 해석하는데 그 목적을 두고 있다. 또한 기존의 해석방법과 본 연구에서의 해석방법을 비교하고 각 강도별로 기존에 제안된 응력블럭을 가정, 강도별에 알맞은 응력블럭을 검증하고 본 연구의 해석방버벵 대한 타당성을 증명하는 데 있다. 그래서 기존의 문헌을 통하여 공시체 데이터($\Phi$10$\times$20)에 대한 회귀분석을 이용하여 각 강도별로 곡선식을 모델화하여 제안하였고 이 식을 이용하여 불확실성을 내포하고 있는 몬테카롤로 시뮬레이션을 사용하여 내력을 평가하여 기존연구 해석치와 각 응력블럭을 이용한 본 연구에서의 해석치를 비교검토하여 이 해석방법의 타당성을 증명하는데 있다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.385-390
• /
• 2003

As growing of industrialization and increasing of population, the quantities of waste glasses are rapidly growing in the earth. It cause some problems such as the waste of natural resources and environmental pollution. In this context, recycling waste glass as a material of concrete has a great advantage environmentally and economically. This study is aimed to investigate the effect of load and deflection on fiber reinforced concrete slab model utilizing waste glass by fine aggregates. The flexural strength of the concrete including waste glass increased considerably, as the inclusion rate of steel fiber were increased. And the first crack load, maximum load and energy absorption capacity increased remarkably as the inclusion rate of steel fiber were increased. Therefore, in this study we confirmed the possibility of application for the usage of waste glass to the steel fiber reinforced concrete.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.606-611
• /
• 2009

MiStrut is a new method to establish structural stability in designing braced excavations by making a rigid connection between top-level steel beams and soldier beams. MiStrut has a function of working as a strut as well as supporting cover plates of top-level steel beams. The structural mechanism of MiStrut is supposed to reduce flexural deformation of soldier beams, which may lead to reduced lateral earth pressures behind excavation. In this research, for verification of the performance of MiStrut, shear-wave velocities of subsurface soil before and after excavation was compared. The rigid connection of main girder beams with soldir beams reduced shear-wave velocity by 67% and lateral earth pressures by 90%, which indicates that MiStrut is effective development in reducing lateral earth pressures on braced excavation.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05a
• /
• pp.391-394
• /
• 2005

A theoretical model was developed to predict the shear strength of slender reinforced concrete beams. The shear force applied to a cross-section of the beam was assumed to be resisted primarily by the compressive zone of intact concrete rather than by the tensile zone. The shear capacity of the cross section was defined based on the material failure criteria of concrete: failure controlled by compression and failure controlled by tension. In the evaluation of the shear capacity, interaction with the normal stresses developed by the flexural moment in the cross section was considered. In the proposed strength model, 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 strength model was verified by the comparisons to prior experimental results.