• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.9-12
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• 2004

Coupling beams subject to cyclic loads exhibit different behavioral characteristics and energy dissipation capacity varying with re-bar layouts. In the present study, nonlinear analysis method was developed using analogous truss model. Using the numerical method, parametric studies were performed to investigate the behavioral characteristics and the energy dissipation mechanism of coupling beams with various re-bar layouts subject to cyclic loading. Based on the investigation, a simple and practical method for evaluating the energy dissipation capacity of coupling beams was developed and verified by experiments. The proposed method accurately predicted the dissipated energy during cyclic loading addressing design parameters such as re-bar layouts, re-bar ratio, and deformation. The proposed method can be easily applied to nonlinear static and dynamic methods for seismic analysis and design.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.333-336
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• 2006

The response of a reinforced concrete element under cyclic shear is characterized by the hysteretic loops of the shear stress-strain curves. Recent tests have shown that the orientation of steel grids in RC shear elements has a strong effect on the "pinching effect" and ductility in the post-yield hysteretic loops. In this paper, four RC elements are considered to study the effect of the steel grid orientation on "pinching effect" and ductility. The presence and absence of the pinching mechanism in the post-yield shear hysteretic loops are studied using the Rotating Angle Softened Truss Model (RA-STM) theory.

• Structural Engineering and Mechanics
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• v.46 no.4
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• pp.519-531
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• 2013

To have a better understanding of the torsional mechanism and influencing factors of PC composite box-girder with corrugated steel webs, ultimate torsional strength of four specimens under pure torsion were analyzed with Model Test Method. Monotonic pure torsion acts on specimens by eccentric concentrated loading. The experimental results show that cracks form at an angle of $45^{\circ}$ to the member's longitudinal axis in the top and bottom concrete slabs. Longitudinal reinforcement located in the center of cross section contributes little to torsional capacity of the specimens. Torsional rigidity is proportional to shape parameter ${\eta}$ of corrugation and there is an increase in yielding torque and ultimate torque of specimens as the thickness of corrugated steel webs increases.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.193-201
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• 2023

In this study, a nonlinear truss finite element is developed to analyze structures with negative Poisson effect-induced tensile buckling. In general, the well-known buckling phenomenon is a stability problem under a compressive load, whereas tensile buckling occurs because of local compression caused by tension. It is not as well-known as classical buckling because it is a recent study. The mechanism of tensile buckling can be briefly explained from an energy standpoint. The nonlinear truss finite element with a torsional spring is formulated because the finite element has not been reported in the literature yet. The post-buckling analysis is then performed using the generalized displacement control method, which reveals that the torsional spring plays an important role in tensile buckling. Structures that mimic a negative Poisson effect can be constructed using such post-buckling behaviors, and one of the possible applications is a mechanical switch. The results obtained are compared to those of analytical solutions and commercial finite element analysis to assess the validity of the proposed finite element model. The numerical results show that the developed finite element model could be a viable option for the basic design of nonlinear structures with a negative Poisson effect.

• Smart Structures and Systems
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• v.8 no.4
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• pp.343-365
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• 2011

Structural system identification (SSI) is an inverse problem of difficult solution. Currently, difficulties lie in the development of algorithms which can cater to large size problems. In this paper, a parameter estimation technique based on evolutionary strategy is presented to overcome some of the difficulties encountered in using the traditional system identification methods in terms of convergence. In this paper, a non-traditional form of system identification technique employing evolutionary algorithms is proposed. In order to improve the convergence characteristics, it is proposed to employ immune algorithms which are proved to be built with superior diversification mechanism than the conventional evolutionary algorithms and are being used for several practical complex optimisation problems. In order to reduce the number of design variables, domain decomposition methods are used, where the identification process of the entire structure is carried out in multiple stages rather than in single step. The domain decomposition based methods also help in limiting the number of sensors to be employed during dynamic testing of the structure to be identified, as the process of system identification is carried out in multiple stages. A fifteen storey framed structure, truss bridge and 40 m tall microwave tower are considered as a numerical examples to demonstrate the effectiveness of the domain decomposition based structural system identification technique using immune algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.211-218
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• 1999

The traditional robot manipulators are actuated by continuous range of motion actuators such as motors or hydraulic cylinders. However, there are many applications of mechanisms and robotic manipulators where only a finite number of locations need to be reached, and the robot’s trajectory is not important as long as it is bounded. Binary manipulator uses actuators which have only two stable states. As a result, binary manipulators have a finite number of states. The number of states of a binary manipulator grows exponentially with the number of actuators. This kind of robot manipulator has some advantage compared to a traditional one. Feedback control is not required, task repeatability can be very high, and finite state actuators are generally inexpensive. And this kind of robot manipulator has a fault tolerant mechanism because of kinematic redundancy. In this paper, we solve the inverse kinematic problem of a binary parallel robot manipulator using neural network and test the validity of this structure using some arbitrary points m the workspace of the robot manipulator. As a result, we can show that the neural network can find the nearest feasible points and corresponding binary states of the joints of the robot manipulator

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.133-141
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• 2001

A tubular member holding an axially through-gusset connection is often used to transmit axial compression in a steel truss structures. The elastic buckling loads of the member is affected by the stiffness ratio($\beta$) and the length ratio(G) because of two elements with different properties. In current code, however, the strength is evaluated with an effective length factor k=0.9 without considering the above effect. Therefore this study analyzed a theoretical mechanism based on the elasticity theory and performed a finite element analysis to investigate the influence parameters on the elastic buckling strength of axially loaded member.

• Earthquakes and Structures
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• v.15 no.2
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• pp.145-153
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• 2018

Extensive reinforced concrete interior beam-column joints with beams of different depths have been used in large industrial buildings and tall building structures under the demand of craft or function. The seismic behavior of the joint, particularly the relationship between deformation and strength in the core region of these eccentric reinforced concrete beam-column joints, has rarely been investigated. This paper performed a theoretical study on the effects of geometric features on the shear strength of the reinforced concrete interior beam-column joints with beams of different depths, which was critical factor in seismic behavior. A new model was developed to analyze the relationship between the shear strength and deformation based on the Equivalent Strut Mechanism (ESM), which combined the truss model and the diagonal strut model. Additionally, this paper developed a simplified calculation method to estimate the shear strength of these type eccentric joints. The accuracy of the model was verified as the modifying analysis data fitted to the test results, which was a loading test of 6 eccentric joints conducted previously.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.335-344
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• 2010

This paper presents both of an investigation on the ultimate responses and a verification study on the structural methodology using beam-truss element of steel transmission towers using experimental study. The partially scaled tower which verified with analytical model was fabricated and the horizontal load was applied up to failure in the laboratory. The structural methodology for finite element analyses was verified against experimental results and both the ultimate load capacity and collapse mechanism were shown in the test to give sufficiently accurate results with those of analytical study. It was shown as well that the ultimate failure is primarily attributed to instability of the main posts in the leg parts.

• Structural Engineering and Mechanics
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• v.10 no.6
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• pp.589-601
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• 2000

A simplified analysis procedure utilizing the strut-tie modeling technique is developed to take a close look into the post-elastic deformation capacity of beam-column connections in ductile reinforced concrete frame structures. Particular emphasis is given to the effect of concrete strength decay and quantity and arrangement of joint shear steel. For this a fan-shaped crack pattern is postulated through the joints. A series of hypothetical rigid nodes are assumed through which struts, ties and boundaries are connected to each other. The equilibrium consideration enables all forces in struts, ties and boundaries to be related through the nodes. The boundary condition surrounding the joints is obtained by the mechanism analysis of the frame structures. In order to avoid a complexity from the indeterminacy of the truss model, it is assumed that all shear steel yielded. It is noted from the previous research that the capacity of struts is limited by the principal tensile strain of the joint panel for which the strain of the transverse diagonal is taken. The post-yield deformation of joint steel is taken to be the only source of the joint shear deformation beyond the elastic range. Both deformations are related by the energy consideration. The analysis is then performed by iteration for a given shear strain. The analysis results indicate that concentrating most of the joint steel near the center of the joint along with higher strength concrete may enhance the post-elastic joint performance.