• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.806-818
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• 2006

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$ becomes $\kappa$, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results.

• Steel and Composite Structures
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• 제46권6호
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• pp.773-791
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• 2023

Connections with damage concentrated to pre-selected components can enhance seismic resilience for moment resisting frames. These pre-selected components always yield early to dissipate energy, and their energy dissipation mechanisms vary from one to another, depending on their position in the connection, geometry configuration details, and mechanical characteristics. This paper presents behaviour insights on two types of beam-to-beam connections that the angles were designed as energy dissipation components, through the results of experimental study and finite element analysis. Firstly, an experimental programme was reviewed, and key responses concerning the working mechanism of the connections were presented, including strain distribution at the critical section, section force responses of essential components, and initial stiffness of test specimens. Subsequently, finite element models of three specimens were established to further interpret their behaviour and response that were not observable in the tests. The moment and shear force transfer paths of the composite connections were clarified through the test results and finite element analysis. It was observed that the bending moment is mainly resisted by axial forces from the components, and the dominant axial force is from the bottom angles; the shear force at the critical section is primarily taken by the slab and the components near the top flange. Lastly, based on the insights on the load transfer path of the composite connections, preliminary design recommendations are proposed. In particular, a resistance requirement, quantified by a moment capacity ratio, was placed on the connections. Design models and equations were also developed for predicting the yield moment resistance and the shear resistance of the connections. A flexible beam model was proposed to quantify the shear resistance of essential components.

• 한국기계가공학회지
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• 제13권6호
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• pp.82-87
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• 2014

Small MR dampers with a simple structure were designed and manufactured. The Bingham model was used to represent the dynamic characteristics of the damper, and the parameters of the model were estimated from experimental data which were obtained by harmonic tests. The value of the estimated yield shear force remains positive when no electric current is applied, and it increases slowly with the current. The estimated viscous damping coefficient has a value close to zero when no electric current is applied, and it increases almost linearly with the current.

• 한국강구조학회 논문집
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• 제13권5호
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• pp.503-511
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• 2001

건물의 내진성을 향상시키는 방법으로 전단벽과 가새 등의 내진요소가 사용된다. 대부분 철근콘크리트 건물에서는 철근콘크리트 전단벽이 철골건물에서는 철골가새가 내진요소로 사용이 되고 있다. 그러나 철근콘크리트 전단벽은 시공이 어렵고 원하는 소성 영역에서 연성(ductility)과 에너지 흡수능력을 만족시키기 어렵다. 강도와 강성이 매우 높고 연성이 우수하며, 자중이 작아서 전단벽의 재료로서 적합하다고 판단된다. 안정적인 거동을 하도록 박강판의 양면에 리브판을 보강하는 방법을 채택하였다. 실험은 강판벽의 폭높이비(D/H) 리브보강형태, 재하이력 등을 변수로 하여 수행하였다. 실험결과로 부터 강판벽의 제반 복원력특성을 분석 고찰하였다.

• Steel and Composite Structures
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• 제42권4호
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• pp.477-487
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• 2022

The shear stiffness of headed-stud shear connectors has no unified definition due to the nonlinear characteristics of its load-slip relationship. A unified framework was firstly adopted to develop a general expression of shear load-slip equation for headed-stud shear connectors varying in a large parameter range based on both force and energy balance. The pre- and post-yield shear stiffness were then determined through bilinear idealization of proposed shear load-slip equation. An updated and carefully selected push-out test database of 157 stud shear connectors, conducting on studs 13~30mm in diameter and on concretes 30~180 MPa in cubic compressive strength, was used for model regression and sensitivity analysis of shear stiffness. An empirical calculation model was also established for the stud shear stiffness. Compared with the previous models through statistical analysis, the proposed model demonstrates a better performance to predict the shear load-slip response and stiffness of the stud shear connectors.

• Steel and Composite Structures
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• 제46권6호
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• pp.823-837
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• 2023

This paper presents the seismic performance of seven beam-column joints with an eccentricity between beam depths under cyclic loadings. The failure modes of the panel zone were divided into two types. One was the shear force failure that appeared in the entire panel zone (SFEPZ), the other was the shear force failure that appeared in the partial panel zone (SFPPZ). Seven finite element models were established using multi-scale methods. Compared with the experimental specimens, the hysteretic loops exhibited a similar trend. The multi-scale models could accurately simulate the experimental results. Furthermore, the calculation formulas of yield and plastic shear capacity of unequal-depth joints with outer annular stiffener were proposed.

• Korea-Australia Rheology Journal
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• 제19권2호
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• pp.75-80
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• 2007

The slotted plate technique has previously been shown to be a successful method for directly measuring the static yield stress of suspensions. In this study, we further establish the usefulness of the slotted plate device as a rheometer especially at low shear rates, taking advantage of the extremely low speeds of the slotted plate technique. Newtonian fluids, a shear thinning fluid, and yield stress fluids were tested using the slotted plate device and the results were compared with those from a commercial rheometer using different standard flow geometries. The relationship between the stress on the plate and the viscosity for the slotted plate device obtained by dimensional analysis (drag) predicts a linear relationship between the force at the plate and the plate speed, consistent with the experimental data. The slotted plate device can measure viscosities at very low shear rates. The apparent viscosity - shear-rate data obtained from the slotted plate device are complementary to those obtained using a commercial rheometer. That is : the slotted plate can measure viscosity in the shear rate range $10^{-7}<\dot{\gamma}<10^{-3}\;s^{-1}$, while the commercial rheometer measures viscosity at shear rates higher than $10^{-3}\;s^{-1}$.

• 한국산학기술학회논문지
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• 제17권12호
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• pp.285-291
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• 2016

본 연구의 목적은 유공강판 전단연결재로 보강된 강관말뚝의 인발실험을 통하여 구조성능을 평가하는 것이다. 인발실험에 앞서 재료의 특성을 파악하기 위하여 콘크리트 압축장도 실험을 수행하였으며, 실험에 사용되는 철근 및 철판의 항복하중, 인장강도 및 연신율 등의 재료적 특성을 미리 파악하였다. 유공강판 전단연결재로 보강된 강관말뚝의 인발실험은 2,000kN 용량의 UTM을 이용하여 0.01mm/sec 재하속도의 변위제어 방법으로 실험을 수행하였다. 계측을 위하여 철근 및 유공강판 중앙에 strain gauge를 부착하였으며, 가력판과 충전콘크리트 사이의 상대변위 측정을 위하여 변위계(LVDT)를 설치하였다. 유공강판 전단연결재로 보강된 실험체의 항복하중은 각각 923.8kN과 981.1kN으로 기존 설계법에 의하여 제작된 실험체의 항복하중인 641.7kN에 비하여 1.44배 ~ 1.53배 증가됨을 알 수 있었다. 또한 유공강판 전단연결재로 보강된 실험체의 극한하중은 각각 1004.4kN과 1055.5kN으로 기존 설계법에 의하여 제작된 실험체의 극한하중인 813.7kN에 비하여 1.23배 ~ 1.29배 증가됨을 알 수 있었다. 반면, 유공강판 전단연결재로 보강된 실험체의 항복변위 및 극한상태의 변위는 기존 설계법에 의하여 제작된 실험체에 비하여 각각 0.61배 및 0.42배 감소됨을 알 수 있었다. 따라서 유공강판 전단연결재로 보강된 강관말뚝은 강성은 증가하고 상대변위 및 변형률은 낮게 측정되어 기존 말뚝머리 보강방법을 대체할 수 있는 적절한 보강방법임 알 수 있었다.

• Earthquakes and Structures
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• 제10권1호
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• pp.1-23
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• 2016

Steel plate shear walls (SPSWs) have been shown to be efficient lateral force-resisting systems, which are increasingly used in new and retrofit construction. These structural systems are designed with either stiffened and stocky or unstiffened and slender web plates based on disparate structural and economical considerations. Based on some limited reported studies, on the other hand, employment of low yield point (LYP) steel infill plates with extremely low yield strength, and high ductility as well as elongation properties is found to facilitate the design and improve the structural behavior and seismic performance of the SPSW systems. On this basis, this paper reports system-level investigations on the seismic response assessment of multi-story SPSW frames under the action of earthquake ground motions. The effectiveness of the strip model in representing the behaviors of SPSWs with different buckling and yielding properties is primarily verified. Subsequently, the structural and seismic performances of several code-designed and retrofitted SPSW frames with conventional and LYP steel infill plates are investigated through detailed modal and nonlinear time-history analyses. Evaluation of various seismic response parameters including drift, acceleration, base shear and moment, column axial load, and web-plate ductility demands, demonstrates the capabilities of SPSW systems in improving the seismic performance of structures and reveals various advantages of use of LYP steel material in seismic design and retrofit of SPSW systems, in particular, application of LYP steel infill plates of double thickness in seismic retrofit of conventional steel and code-designed SPSW frames.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.275-284
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• 2017

A formula to estimate the yield displacement observed in the pushover analysis of coupled wall lateral force-resisting systems is presented. The estimate is based on the results of an analytical study of coupled walls ranging from 8 to 20 stories in height, with varied amounts of reinforcement in the reinforced concrete coupling beams and walls, subjected to first-mode pushover analysis. An example illustrates the application of these estimates to the performance-based seismic design of coupled walls.