• Computers and Concrete
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• 제31권4호
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• pp.337-348
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• 2023

Shear wall is commonly used as a lateral force resisting system of concrete mid-rise and high-rise buildings, but it brings challenges in providing relatively large space throughout the building height. For this reason, the structure system where the upper structure with bearing, non-bearing and/or shear walls that sits on top of a transfer plate system supported by widely spaced columns at the lower stories is preferred in some regions, particularly in low to moderate seismic regions in Asia. A thick reinforced concrete (RC) plate has often been used as a transfer system, along with RC transfer girders; however, the RC plate becomes very thick for tall buildings. Applying the post-tensioning (PT) technique to RC plates can effectively reduce the thickness and reinforcement as an economical design method. Currently, a simplified model is used for numerical modeling of PT transfer plate, which does not consider the interaction of the plate and the upper structure. To observe the actual behavior of PT transfer plate under seismic loads, it is necessary to model whole parts of the structure and tendons to precisely include the interaction and the secondary effect of PT tendons in the results. This research evaluated the seismic behavior of shear wall-type residential buildings with PT transfer plates for the condition that PT tendons are included or excluded in the modeling. Three-dimensional finite element models were developed, which includes prestressing tendon elements, and response spectrum analyses were carried out to evaluate seismic forces. Two buildings with flat-shape and L-shape plans were considered, and design forces of shear walls and transfer columns for a system with and without PT tendons were compared. The results showed that, in some cases, excluding PT tendons from the model leads to an unrealistic estimation of the demands for shear walls sit on transfer plate and transfer columns due to excluding the secondary effect of PT tendons. Based on the results, generally, the secondary effect reduces shear force demand and axial-flexural demands of transfer columns but increases the shear force demand of shear walls. The results of this study suggested that, in addition to the effect of PT on the resistance of transfer plate, it is necessary to include PT tendons in the modeling to consider its effect on force demand.

• 소성∙가공
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• 제29권6호
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• pp.331-337
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• 2020

Blind rivet nuts (BRNs) are increasingly used in automotive industry because unlike conventional bolt fastening, BRN fastening requires access from one side only. Generally, fastening is conducted using automated units, but manual fastening may be resorted to in case of small quantities. Since the fastening direction is not exactly perpendicular to the sheet metal, the BRN axis is tilted with respect to the plate and may result in damage or incomplete fastening. As the tilt angle (clamping angle α) increases, undesired plate deformation occurs and the contact area of the plate with the BRN fastening area decreases, reducing the clamping effect. In this study, the reduction of the clamping effect with the α was investigated to ensure stable fastening force. M6 BRNs were used in the tests. The fastening force was measured as follows: the plate was cut in half through the center of the hole; the BRN was inserted into the hole and fastened; and the clamping angle a was measured (values, 0° ≤ α ≤ 9°). The force leading to the separation of the halves was measured using a universal testing machine (UTM). The maximum α range, in which the fastening force remains stable, was determined. Finite element (FE) analysis confirmed that the fastening force decreases approximately linearly with increasing α. Based on the experiment and FE analysis using various α, the fastening force was found to decrease with α. Further, the maximum tolerance for α that provides secure fastening without damage is suggested.

• Transactions on Control, Automation and Systems Engineering
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• 제3권1호
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• pp.66-70
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• 2001

This paper describes the design of a two-axis force sensor for robots finger. In detects the x-direction force Fx and y-direction force Fy simultaneously. In order to safely grasp an unknown object using the robots fingers, they should detect the force or gripping direction and the force of gravity direction, and perform the force control using the forces detected. Therefore, the robots hand should be made by the robots finger with tow-axis force sensor that can detect the x-direction force and y-direction force si-multaneously. Thus, in this paper, the two-axis force sensor for robots finger is designed using several parallel-plate beams. The equations to calculate the strain of the beams according to the force in order to design the sensing element of the force sensor are derived and these equations are used to design the aize of two-axis force sensor sensing element. The reliability of the derive equa-tions is verified buy performing a finite element analysis of the sensing element. The strain obtained through this process is compared to that obtained through the theory analysis and a characteristics test of the fabricated sensor. It reveals that the rated strains calculated from the derive equations make a good agreement with the results from the Finite Element Method analysis and from the character-istic test.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2831-2836
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• 2009

고장력볼트를 이용한 강부재의 연결부에서 마찰력을 초과하는 설계하중이 작용하여 미끄럼이 발생하는 점을 기점으로 볼트와 모재의 전단강도 및 지압강도에 의해 설계하중을 지지하게 된다. 미끄럼량은 볼트의 장력, 접촉면의 마찰계수, 모재구멍내에서 볼트의 위치에 따라 결정되어 질 수 있다. 본 연구에서는 모재 및 덮개판에 대하여 볼트구멍의 크기를 변화시켜 제작된 고장력볼트 체결부에 순수굽힘과 인장력이 작용하는 경우 표준공과 과대공에 따른 미끄럼을 측정하고 비교분석하였다. 표준공을 가지는 경우보다 과대공을 가지는 경우에 $74\sim94%$ 작은 하중에서 미끄럼이 발생하였다. 인장력을 받는 부재에서는 과대공치수가 클수록 미끄럼 하중비가 작게 나타났으며 모재의 과대공치수가 덮개판의 과대공치수보다 미끄럼하중변화와 연관성이 많은 것으로 나타났다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.723-727
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• 2003

In this paper, two methods are discussed for good rolling force prediction in a plate mill. One is about the development of a long and a short learning scheme using a Neural Network for normal rolling and the other is about a mathematical model improvement by considering microstructural changes for controlled rolling. The research results are implemented in a on-line system of Pohang Works in POSCO and the field tests have showed that the prediction accuracies of rolling force are highly improved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.2986-2988
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• 1999

This paper presents a new concept to implement and to control of tactile reproduction simulator by implementation of compliance emulator system. Compliance emulator system is a kind of levitation system using magnetic force. In the compliance emulator system, a floated plate moves vertically. When an external force is applied to the plate, the system produces a controlled reaction force by using 6 electromagnet. For the control, a LVDT displacement sensor and PD control method is used.

• ALGAE
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• 제20권2호
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• pp.151-155
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• 2005

To obtain basic data, we investigated the effect of blade length on transplants, the transplanting method of Laminaria japonica for creating L. japonica resources and the number of transplanting plates with surviving L. japonica. The survival rate of L. japonica, blade length of transplants and drag force of transplanting plates were also researched. The number of transplanting plates with surviving L. japonica, the survival rate and blade length of 20 cm long-initial transplants were greater than those of 1.5, 5 and 10 cm long-initial transplants in an outdoor aquarium. At the depth of 4 m in the coastal waters, the number of transplanting plates with surviving transplants, the survival rate and the blade length of 30 cm long-initial transplants were higher than those of 10 and 20 cm longinitial transplants. The drag force is calculated by cording up sporophytes of L. japonica into the transplanting plates under water. The drag force in the case of a 2.18 kg-weight transplanting plate and in a current speed of 0.5 m${\cdot}s^{-1}$ for considering stability of the plate was 631.50 g to a concrete substratum on the seabed, 703.92 g to a shingle substratum, 788.00 g to a sand substratum, and 1018.30 g to a silt substratum. If we consider the stability and economic efficiency of the transplanting plate, the proper weight of the plate per one individual of 18.11 cm in blade width and 190.20 cm in total blade length is regarded as 508.2 g when it is calculated with the concrete substratum that shows the lowest drag force.

• Interaction and multiscale mechanics
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• 제2권2호
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• pp.177-187
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• 2009

Machine or structural members subjected to fatigue loading will have a crack initiated during early part of their life. Therefore analysis of members with cracks and other discontinuities is very important. Finite element method has enjoyed widespread use in engineering, but it is not convenient for crack problems as the region very close to crack tip is to be discretized with very fine mesh. However, as the body force method (BFM), requires only the boundary of the discontinuity (crack or hole) to be discretized it is easy versatile technique to analyze such problems. In the present work fundamental solution for concentrated load x + iy acting in the semi-infinite plate at an arbitrary point $z_0=x_0+iy_0$ is considered. These fundamental solutions are in complex form ${\phi}(z)$ and ${\psi}(z)$ (England 1971). These potentials are known as Melan potentials (Ramakrishna 1994). A crack in the semi-infinite plate as shown in Fig. 1 is considered. This crack is divided into number of divisions. By applying pair of body forces on a division, the resultant forces on the remaining 'N'divisions are to be found for which ${\phi}_1(z)$ and ${\psi}_1(z)$ are derived. Body force method is applied to calculate stress intensity factor for crack in semi-infinite plate. Also for the case of crack emanating from circular hole in semi-infinite plate radial stress, hoop stress and shear stress are calculated around the hole and crack. Convergent results are obtained by body force method. These results are compared with FEM results.

• Steel and Composite Structures
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• 제44권3호
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• pp.437-450
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• 2022

When the vertical load-bearing members in high-rise structures fail locally, the beam-column joints play an important role in the redistribution of the internal forces. In this paper, a static laboratory test of three full-scale flush flange beam-reinforced connections with side and cover plates (CP-FBSP connection) with double half-span steel beams and single L-shaped columns composed of concrete-filled steel tubes (L-CFST columns) was conducted. The influence of the side plate width and cover plate thickness on the progressive collapse resistance of the substructure was thoroughly analyzed. The failure mode, vertical force-displacement curves, strain variation, reaction force of the pin support and development of internal force in the section with the assumed plastic hinge were discussed. Then, through the verified finite element model, the corresponding analyses of the thickness and length of the side plates, the connecting length between the steel beam flange and cover plate, and the vertical-force eccentricity were carried out. The results show that the failure of all the specimens occurred through the cracking of the beam flange or the cover plate, and the beam chord rotations measured by the test were all greater than 0.085 rad. Increasing the length, thickness and width of the side plates slightly reduced the progressive collapse resistance of the substructures. The vertical-force eccentricity along the beam length reduced the progressive collapse resistance of the substructure. An increase in the connecting length between the beam flange and cover plate can significantly improve the progressive collapse resistance of substructures.

• Steel and Composite Structures
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• 제18권6호
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• pp.1423-1450
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• 2015

The paper presents the details and results of an experimental study on bolted end-plate joints of industrial type steel building frames. The investigated joints are commonly used in Lindab-Astron industrial buildings and are optimized for manufacturing, erection and durability. The aim of the research was to provide an experimental background for the design model development by studying load-bearing capacity of joints, bolt force distribution, and end-plate deformations. Because of the special joint details, (i.e., joints with four bolts in one bolt-row and HammerHead arrangements), the Eurocode 3 standardized component model had to be improved and extended. The experimental programme included six different end-plate and bolt arrangements and covered sixteen specimens. The steel grade of test specimens was S355, the bolt diameter M20, whereas the bolt grade was 8.8 and 10.9 for the two series. The end-plate thickness varied between 12 mm and 24 mm. The specimens were investigated under pure bending conditions using a four-point-bending test arrangement. In all tests the typical displacements and the bolt force distribution were measured. The end-plate plastic deformations were measured after the tests by an automatic measuring device. The measured data were presented and evaluated by the moment-bolt-row force and moment-distance from centre of compression diagrams and by the deformed end-plate surfaces. From the results the typical failure modes and the joint behaviour were specified and presented. Furthermore the influence of the end-plate thickness and the pretension of the bolts on the behaviour of bolted joints were analysed.