Steel plate shear walls (SPSWs) have been recognized as an effective seismic-force resisting systems due to their excellent strength and stiffness characteristics. The infill steel plate in a SPSW is constrained by a boundary frame consisting of vertical and horizontal structural members. The main purpose of this study was to investigate deformation modes and hysteretic characteristics of steel plate shear walls (SPSWs) to consider the effects of their aspect ratios and width-to-thicness ratios. The finite element model (FEM) was establish in order to simulate cyclic responses of SPSWs which have the two-side clamped boundary condition and made of conventional steel grade. The stress distribution obtained from the FEA results demonstrated that the principal stresses on steel plate with large thickness-to-width ratio were more uniformly distributed along its horizontal cross section due to the formation of multiple struts.

Friction stir spot welding (FSSW) is a solid-state joining process and a rapidly growing dissimilar material welding technology for joining metallic alloys in the automotive industry. Welding tool shape and process conditions must be appropriately controlled to obtain high bonding characteristics. In this study, FSSW is performed on dissimilar materials AA5052-H32 aluminum alloy sheet and SPRC440 steel sheet, and the influence of the shape of joining tool and tool insertion depth during joining is investigated. A new intermetallic compound is produced at the aluminum and steel sheets joint. When the insertion depth of the tool is insufficient, the intermetallic compound between the two sheets did not form uniformly. As the insertion depth increased, the intermetallic compound layer become uniform and continuous. The joint specimen shows higher values of tensile shear load as the diameter and insertion depth of the tool increase. This shows that the uniform formation of the intermetallic compound strengthens the bonding force between the joining specimens and increases the tensile shear load.

Modular construction is an economical and efficient construction that reduces time and costs by manufacturing units in factories and constructing them on site. Currently, the demand for modular construction is increasing not only abroad but also domestically. As the demand for modular construction increases, a lot of development and research on connections between modular units are being conducted. Connections between modular units should be quick and simple to assemble when assembling units on site, and should be in a form that allows each unit to be connected regardless of direction. In addition, it must be able to exert sufficient strength against external loads. In this study, a connection between modular units using connecting steel plates and bolts was proposed, and the nonlinear behavior of the connection to external lateral force was analyzed through finite element analysis, and resistance performance was evaluated.

이 연구에서는 강관말뚝과 확대기초의 연결을 위한 유공강판 전단연결재를 개발하기 위하여 유공전단키의 형상을 결정하기 위한 인장실험과 유한요소해석을 수행하였다. 즉, 인장시험편과 같은 평판 형태의 유공강판은 펀치 형 돌기와 굴곡형 돌기의 유공전단키를 갖도록 형성하고 이을 원주형 콘크리트 내에 매립하여 인장실험을 수행하였 으며, 실험 결과는 유한요소해석 결과와 비교하였다. 또한, 유한요소해석을 수행하여 적절한 유공전단키의 종류 및 돌기 폭을 결정하였으며, 이를 통해 결정한 굴곡형 유공전단키에 대한 높이를 결정하기 위한 추가 해석을 수행하였 다. 해석 결과, 굴곡형 돌기의 경우에는 전단저항력을 최대로 확보하고 인장력의 저하를 최소화하기 위하여 돌기의 높이를 두께의 2배로 하는 것이 바람직할 것으로 판단된다.

In this study, based on the research results of the steel plate and steel rod dampers with rocking behavior, the moment and the drift ratio were compared and evaluated. As a test result evaluation, it was showed that the behavior of R15-200 and R15-140 was very good than other dampers. And the steel rod damper showed in-plane behavior to the loading direction, and was evaluated to prevent out-of-plane behavior that causes performance degradation.

In this paper, based on the finite element analysis model verified in previous studies, a new model of a buckling restrained brace reinforced with a steel plate was proposed. A design formula was proposed for the new model to dissipate energy without buckling the steel core under load protocol, and the performance of the model satisfying the design formula was evaluated by comparing it with the previous model through the results of hysteresis loop, bi-linear curve, cumulative energy dissipation capacity, and equivalent viscous damping.

교각의 내구성 증진 및 내진 보강을 위하여 원형철근 콘크리트 교각 외부에 강판을 보강한 경우, 교각 외부에서 발 생하는 화재에 대해 보강된 교각의 내화성능을 정량적으로 평가하였다. 범용유한요소해석프로그램 ABAQUS를 이용하였으며 ISO 834-1의 표준화재곡선을 적용하여 교각의 거동을 해석하였다. 해석 변수로는 강판보강두께와 원형교각 지름의 비, 교각에 수직으로 작용하는 축력비를 적용하였다. 교각의 상부와 하부는 힌지-롤러 경계조건을 고려하여 상부는 수직으로 변위가 발생하 도록 하였으며, 교각 외부 전체에 열하중을 가하였고 편심 없는 순수 축하중을 교각 중앙에 가력하였다. 온도에 따른 콘크리트, 철근 및 강재의 비열, 열전도율, 탄성계수 등을 고려하여 보강에 따른 교각의 내화 성능 향상도를 평가하였다. 강판으로 보강한 원형철근 콘크리트 교각은 콘크리트의 중심부일수록 강판 두께의 영향을 받지 않으며 강판 두께별 축력을 주 었을 때 내화시간은 축력비 0.7에서 최대 약 3분 향상되었다. 또한, 보강두께가 두꺼울수록 내하력이 향상하며 60분 이후에 모 두 내하력비가 1.0 이하로 감소하기 시작하는 것을 알 수 있었다. 강판보강공법은 내화성능을 향상시킬 수 있으며 강판 보강 두 께와 보강 지름의 비가 클수록 화재에 대해 축방향에 대한 변위와 내하력이 증가하는 것으로 나타났다. 본 연구결과를 토대로 원형철근 콘크리트 교각의 외부 강판 보강을 통하여 교각의 내화 성능을 향상시킬 수 있음을 정량적으로 판단할 수 있었다.

This paper conducted a comparative analysis of the shear buckling characteristics of trapezoidal and sinusoidal corrugated steel plates considering of their initial imperfection. Initial imperfection refers to the state where the shape of the corrugated plate is initially not perfect. As such, an initially imperfect shape was assumed using the eigen buckling mode. To calculate the buckling stress of corrugated steel plates, the linear buckling analysis used a boundary condition which was applied to the plate buckling analysis. For the comparison of trapezoidal and sinusoidal corrugation, the shape parameters were assumed using the case where the length and slope of each corrugation were the same, and the initial imperfection was considered to be from 0.1% to 5% based on the length of the steel plate. Here, for the buckling analysis, ANSYS, a commercial FEA program, was used. From the results of buckling analysis, the effect of overall initial imperfection showed that the larger the initial imperfection, the lower the buckling stress. However, in the very thin model, interaction or local buckling was dominant in the perfect shape, and in this case, the buckling stress did not decrease. Besides, the sinusoidal model showed higher buckling stress than the trapezoidal one, and the two corrugation shapes decreased in a similar way.

Motors are becoming an environment-friendly alternative around the world. Environment-friendly automobile parts in particular require high quality and productivity. To improve these requirements, we studied a manufacturing technology called mold technology. A disadvantage of mold mass-production is a fatigue failure after a relatively large amount of friction and pressure on the processed products. Eventually, this leads to problems of repair costs, production stoppages, and quality defects. To address these problems, a surface- treatment technique is often used to improve mechanical properties by coating the mold surfaces. In this study, we measured the abrasion on (1) Tungsten Carbide punch and (2) TiAlCrN coated punch during the mold mass-production of the cold-rolled steel plate motor core made with SCP-1 (thickness of 1.0mm). With the extracted data, it is proved that using TiAlCrN coated punch affects the reduction of the inner diameter damage of the product. Furthermore, our goal is to reduce repair cost and improve productivity by predicting the lifespan of the mold and identifying the time expectancy of grinding, maintenance, and repair of the mold.

Spot welding is a representative process in automotive welding and the application of intelligent systems is accelerating. In particular, in the case of welding electrode management, the timing of electrode wear and dressing was determined by continuous spot welding evaluation, however there is concerned that errors in welding equipment or processes may work in a complex manner. In this study, a dynamic resistance waveform sensing and image measurement system that greatly affects the nugget formation, which is important to the quality of spot welding, was fabricated and used. Based on the experimental data of the galvanized steel sheet, an electrode life prediction algorithm for electrode wear was derived through CNN(Convolutional Neural Network) model of machine learning training.

In this study, we will develop a hybrid cross-sectional shape of steel inserted type glued-laminated timber that can improve the strength of structural glued-laminated timber and maximize the ductility by using steel plate with excellent tensile and deformation ability. A total of three specimens were fabricated and the flexural performance test was carried out to evaluate the structural performance of the steel inserted type glued-laminated timber. In order to compare the effect of steel inserted glued-laminated timber, one structural glued-laminated timber test specimen composed of pure wood was manufactured. In addition, in order to evaluate the adhesion performance of the steel inserted, one each of a screw joint test specimen and a polyurethane joint test specimen was prepared. As a result, all the specimens showed the initial crack in the finger joint near the force point. This has been shown to be a cause of crack diffusion and strength degradation. The use of finger joints in the maximum moment section is considered to affect the strength and ductility of the glued-laminated timber beam. Polyurethane-adhesive steel inserted glued-laminated timber showed fully-composite behavior with little horizontal separation between the steel plate and glued-laminated timber until the maximum load was reached. This method has been shown to exhibit sufficient retention bending performance.

A corrugated steel plate wall (CSPW) system is advantageous to secure the strength and stiffness required for lateral force resistance because of its high out-of-plane stability. It can also stably dissipate large amounts of energy even after peak strength. In this paper, a preliminary study has been carried out to use the CSPW system in the seismic retrofit of existing reinforced concrete (RC) moment frame buildings. The seismic performance for an example building was evaluated, and then a step-by-step retrofit design procedure for the CSPW was proposed. An equivalent analytical model of the CSPW was also introduced for a practical analysis of the retrofitted building, and the strengthening effect was finally evaluated based on the results of nonlinear analysis.

일반적인 구조용 강재의 경우 항복변형률의 이상의 변형을 경험한 이후에 하중을 제거하면 재가력되는 시점에 따라 서 재료의 항복강도는 증가하고 연성이 감소하는 현상을 보인다. 원형강관의 경우 철판을 말아서 제작하는 과정에서 철판의 두 께와 원형강관의 직경에 따라서 항복변형률이상의 큰 변형을 경험하게 되고 이러한 변형은 제작된 강관의 구조적인 성능에 많 은 영향을 미친다. 이러한 이유에서 제작과정에 발생하는 변형이 원형강관의 구조성능에 미치는 영향을 파악할 필요가 있다. 따 라서, 이 연구에서는 원형강관을 제작하는 경우에 발생하는 변형에 의한 철판의 항복강도, 인장강도 및 연성 등의 영향을 파악 하기 위해서 강관의 직경 및 두께와 시험편을 채취한 방향을 변수로 다수의 인장실험을 수행하고 이를 분석하였다. 실험 결과 를 바탕으로 원형강판에서 채취한 시험편은 코일에서 채취한 시험편에 비해 항복강도와 인장강도가 더 높았고, 연신율은 낮아 진 것으로 나타났다.

This paper discusses the influence of transverse reinforcement spacing and support width of concrete wide beam on shear performance. In order to evaluate the shear performance, a total of thirteen specimens were constructed and tested. The transverse reinforcement spacing, the number of legs and support width were considered as variables. From the test results, the shear strength equation of concrete wide beam is proposed for prediction of shear strength of concrete wide beam to consider the transverse reinforcement spacing and support width. It is shown that the proposed equation is able to predict shear strength reasonably well for concrete wide beam.