Numerical study on force transfer mechanism in through gusset plates of SCBFs with HSS columns & beams

S. Ebrahimi,S.M. Zahrai,S.R. Mirghaderi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.6

In Special Concentrically Braced Frames (SCBFs), vertical and horizontal components of the brace force must be resisted by column and beam, respectively but normal force component existing at the gusset plate-to-column and beam interfaces, creates out-of-plane action making distortion in column and beam faces adjacent to the gusset plate. It is a main concern in Hollow Structural Section (HSS) columns and beams where their webs and gusset plate are not in the same plane. In this paper, a new gusset plate passing through the HSS columns and beams, named as through gusset plate, is proposed to study the force transfer mechanism in such gusset plates of SCBFs compared to the case with conventional gusset plates. For this purpose, twelve SCBFs with diagonal brace and HSS columns and twelve SCBFs with chevron brace and HSS columns and beams are considered. For each frame, two cases are considered, one with through gusset plates and the other with conventional ones. Based on numerical results, using through gusset plates prevents distortion and out-of-plane deformation at HSS column and beam faces adjacent to the gusset plate helping the entire column and beam cross-sections to resist respectively vertical and horizontal components of the brace force. Moreover, its application increases energy dissipation, lateral stiffness and strength around 28%, 40% and 32%, respectively, improving connection behavior and raising the resistance of the normal force components at the gusset plate-to-HSS column and beam interfaces to approximately 4 and 3.5 times, respectively. Finally, using such through gusset plates leads to better structural performance particularly for HSS columns and beams with larger width-to-thickness ratio elements.

Identification of impact force in thick plates based on the elastodynamics and time-frequency method (I)

Sang Kwon Lee 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.7

Determination of impact load is important for detecting and analyzing the flaws in thick plate. In industrial plants, thick aluminum plate is popularly used and impact load is identified by convolving the acoustic waveform, which is measured with sensors arrayed on the plate, and by Green’s function, which is the transfer function between impacting position and sensor. In practical situations, it is difficult to measure Green’s function. In this paper, the impact load on the plate is inversely recovered by using Green’s function and the acoustic waveform. Green’s function and the acoustic waveform are theoretically obtained based on the plate theory. There are three plate theories. One is the classic plate theory (CPT), which has been used for thin plate. The others are the exact plate theory and the approximated shear deformation theory (SDPT), which are used for the thick plate because the CPT overestimates the group velocity at high frequency in the thick plate. In this paper, the thick plate theory is used for the prediction of the acoustic waveform. This theoretical Green’s function can be also used for the inverse problem of impact load based on the experimental method

Design of Three-Axis Force/Torque Sensor for Rehabilitation Robot

정재현(Jae-Hyun Jung),김갑순(Gab Soon Kim) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.4

In this study, we described the design of a three-axis force/torque sensor for measuring the force and torque in a lower-limb rehabilitation robot. The three-axis force/torque sensor is composed of Fx force sensor, Fz force sensor and Tz torque sensor. The sensing element for Fx force sensor and Tz torque sensor is used in a two-step parallel plate beam, and that of Fz force sensor is used in a parallel plate beam. The rated loads of Fx force sensor, Tz torque sensor and Fz force sensor are 300 N, 15 N m and 100 N, respectively. The three-axis force/torque sensor was designed using the finite element method, and manufactured using strain-gauges. The three-axis force sensor was further characterized. As a result, the interference error of the three-axis force/torque sensor was < 1.24%, the repeatability error of each sensor was < 0.03%, and the non-linearity was < 0.02%.

Experimental study on the method of estimating the vertical design wave force acting on a submerged dual horizontal plate

권혁민,오상호,최영환 대한조선학회 2013 International Journal of Naval Architecture and Oc Vol.5 No.4

A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974)that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.

Experimental study on the method of estimating the vertical design wave force acting on a submerged dual horizontal plate

Kweon, Hyuck-Min,Oh, Sang-Ho,Choi, Young-Hwan The Society of Naval Architects of Korea 2013 International Journal of Naval Architecture and Oc Vol.5 No.4

A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.

그라운드 앵커 베어링 플레이트의 원주 방향 변형률 분포 연구

권일범,권용석,서대철,김은호,윤상영 한국비파괴검사학회 2018 한국비파괴검사학회지 Vol.38 No.6

The circumferential strain of a ground anchor bearing plate was examined to measure the tensile force of the anchor. The basic deformation behavior of the bearing plate was investigated by finite element analysis. The bearing plate, with a tensile force of 10 tons administered to it, was subjected to compressive deformation by the anchor head and bending deformation by the reaction force of the anchor structure. The circumferential strain of the bearing plate surface occurred more in other parts than on the edge of the plate. In addition, the circumferential strain of the bearing plate was measured by a self-fabricated fiber optic optical frequency domain reflectometer (OFDR) sensor. This OFDR sensor was operated by shifting positions on the fiber optic line in steps of 1mm over a segment length of 5 cm corresponding to the gage length. From the results of measuring the circumferential distribution strain of the bearing plate surface, it can be seen that the bending deformation due to the fixing jig appears to be larger than the compression deformation due to the anchor head. Therefore, it was noted that it is difficult to determine the anchor tensile force by only one or two strains of the bearing plate surface. In addition, it is expected that the anchor head tensile force can be obtained from the averaged circumferential strains of the center portion of the lateral and longitudinal sides of the bearing plate. 앵커의 인장력을 측정하기 위하여 베어링 플레이트의 원주 방향 변형률을 고찰하였다. 유한요소해석에 의하여 베어링 플레이트의 기본적인 변형 거동을 고찰하였다. 10t의 인장력을 받는 베어링 플레이트는 앵커헤드에 의한 압축 변형과 앵커 구조체의 반력에 의한 굽힘 변형을 받고 있었다. 베어링 플레이트 표면의 원주방향 변형률은 플레이트의 모서리를 제외한 다른 부분에서 더 많이 발생하고 있었다. 또한, 베어링 플레이트의 원주 방향 변형률은 자체 제작한 광섬유 OFDR(optical frequency domain reflectometer) 센서로 측정하였다. 광섬유 OFDR 센서는 게이지길이에 해당하는 세그먼트 사이즈 5 cm로 1 mm씩 광섬유 라인위의 위치를 옮겨가며 작동되었다. 베어링 플레이트 표면의 원주 방향 분포 변형률을 측정한 결과 앵커 헤드에 의한 압축 변형보다 고정 치구에 의한 굽힘 변형이 더 크게 나타나고 있음을 볼 수 있다. 그러므로, 앵커 헤드 인장력은 베어링 플레이트 표면의 한 두 개의 변형률만으로 결정하기는 어려움을 알 수 있었다. 또한, 베어링 플레이트의 가로 및 세로 변 중앙부의 원주 방향 변형률 들의 평균값을 사용하면 앵커 헤드 인장력을 구할 수 있을 것으로 기대된다.

다각(多角)으로 Swaging된 판형연료집합체의 인장시험 평가

송화영(Hwa-young Song),권선칠(Sun-chil Kwaon),김수성(Soo-Sung Kim),정용진(Yong-Jin Jeong),박종만(Jong-Man Park) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.5

Korea Atomic Energy Research Institute (KAERI) has made plate-type fuel assembly to operate Ki-Jang Research Reactor (KJRR). This assembly is combined with both 21 plate-type fuel plates made by mixing both U, Al-5Si powders and seven kinds of AA6061-T6 assembling parts. KAERI invented a swaging machine to put 21 plate-type fuel plates into 2 side plates. The fuel plates are fixed by indentation force of a pair of rollers in the middle of grooves of the side plates. One of the most important conditions in tension test is the angle of the rollers. KAERI carried out a tension test in 3 conditions (0, 30, 45 degrees) to confirm an appropriate indentation force for plate-type fuel assembly. The integrity of the assembly made by swaging machine was confirmed by the result of the tension test of specimens.

A Study on the design of separation force measuring system for improvement of semiconductor productivity

Kun-Jong Park(박군종) 한국컴퓨터정보학회 2017 韓國컴퓨터情報學會論文誌 Vol.22 No.10

In this paper, the separation force measuring system is developed. The separation force aries due to adhesive strength between semiconductor epoxy molding compound(EMC) and the metal plate in semiconductor formed plate. In general, when removing the metal plate in semiconductor formed plate from semiconductor epoxy molding compound, excessive strength can result in a increase in semiconductor defect rates, or conversely, if too little force is exerted on the metal plate in semiconductor formed plate, the semiconductor production rates can decrease. In this study, the design criteria for the selection of the AC servo motor, the role of the ball screw, the relationship between the load cell and the ball screw, and the rate of deceleration are given. In addition, minimizing the reject rate of semiconductors and maximizing the semiconductor production rate are achieved through the standardization of the collected separation force data measured by the proposed system.

Design equation to evaluate bursting forces at the end zone of post-tensioned members

Joung Rae Kim,Hyo-Gyoung Kwak,Byung-Suk Kim 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.5

Design equations to evaluate the bursting force in a post-tensioned anchorage zone have been introduced in many design codes, and one equation in AASHTO LRFD is widely used. However, this equation may not determine the bursting force exactly because it was designed on the basis of two-dimensional numerical analyses without considering various design parameters such as the duct hole and shape of the bearing plate. To improve the design equation, modification of the AASHTO LRFD design equation was considered. The behavior of the anchorage zone was investigated using three-dimensional linear elastic finite element analysis with design parameters such as bearing plate size and diameter of sheath hole. Upon the suggestion of a modified design equation for evaluating the bursting force in an anchorage block with a rectangular anchorage plate (Kim and Kwak 2018), additional influences of design parameters that could affect the evaluation of bursting force were investigated. An improved equation was introduced for determining the bursting force in an anchorage block with a circular anchorage plate, using the same procedure introduced in the design equation for an anchorage block with a rectangular anchorage plate. The validity of the introduced design equation was confirmed by comparison with AASHTO LRFD.

A Transplantation method of Laminaria japonica Areschoug (Laminariales, Phaeophyta)

Woong-Yong Kim,정익교,Sung-Je Choi,신종암 한국조류학회I 2005 ALGAE Vol.20 No.2

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·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.