• Structural Engineering and Mechanics
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• 제81권5호
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• pp.551-563
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• 2022

Bolted connector could be an alternative to replace the conventional welded headed stud in steel-ultra high performance concrete (UHPC) lightweight composite structures. In this paper, a novel demountable bolted shear connector, consisting of a high-strength bolt (HSB) and a specially-designed nut which is pre-embedded in a thin UHPC slab, is proposed, which may result in the quick installation and disassembly, due to the mountable, demountable and reusable features. In order to study the shear behavior of the new type of bolted shear connector, static push-out tests were conducted on five groups of the novel demountable bolted shear connector specimens and one group of conventional welded headed stud specimen for comparison. The effect of the bolt shank diameter and aspect ratio of bolt on failure mode, shear stiffness, peak slip at the steel-UHPC interface, shear strength and ductility of novel bolted connectors is investigated. Additionally, design formula for the shear strength is proposed to check the suitability for assessment of the novel demountable bolted shear connectors.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.53-60
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• 2019

In this study, an experimental study was carried out to evaluate the bond shear performance according to the shear connector between the glue-laminated timber and steel interface. Ten block shear specimens were fabricated according to the configuration of the adhesive surface of wood and steel. In addition, four test specimens were produced according to the main variable shape of the wood-concrete shear connector. As a result of the block shear test, the shear strength of the steel-wood adhesive is shown to have a shear performance greater than the wood-wood shear strength. As a result of the push-out test according to the shape of the shear connector, the shear strength increased linearly with the attachment area. The complete composite behavior between the glued-laminated timber and the steel can be secured.

• 한국대기환경학회지
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• 제16권2호
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• pp.129-140
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• 2000

Simulation study has been carried out to analyze the air flow supplying from the heat pump system inside the tollgate booth by using the Phoenix computer simulation program. Through this simulation analysis we can find the problem of present tollgate booth in terms of air flow and recommend an improved model also simulate this model. Final results as follows; It was turned out that the fresh air conditioning is not provided to the worker effectively due to the improper location of inlet and outlet in the present tollgate booth in addition to that the air curtain system applied in the booth lowered air circulation from outside. The improved model was suggested first to increase the air curtain effect by downsizing the window and by installation of the air curtain suction line to reduce the induced outdoor air second to supply the fresh air to the worker directly by relocation of the inlet and outlet of supplying air. With these improved modifications better results have been reached in terms of air flow inside the booth. Next through the air flow simulation of outside booth the contaminated outdoor air has been easuily infiltrating into the booth through the window because of its rectangle shape. Stream like shape of booth has been proposed through the computer simulation as an alternative shape of tollgate booth for a new design.

• Earthquakes and Structures
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• 제8권5호
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• pp.1191-1214
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• 2015

The Theory of Plastic Mechanism Control (TPMC) has been recently extended to the case of Eccentrically Braced Frames (EBFs) with inverted Y-scheme, i.e., EBFs with vertical links. In this paper a further validation of the design procedure, based on TPMC, is provided by means of Incremental Dynamic Analyses (IDA) pointing out the fulfilment of the design goal, i.e., the development of a pattern of yielding consistent with the collapse mechanism of global type where all the links are yielded and all the beams are yielded at their ends while all the columns and the diagonal braces remain in elastic range with the only exception of the base sections of first storey columns. In particular, a study case is designed according to both TPMC and Eurocode 8 provisions and the corresponding seismic performances are investigated by both push-over and IDA analyses. The results show the different performances obtained in terms of pattern of yielding, maximum interstorey drift, link plastic rotation demand and sharing of the seismic base shear between the moment-resisting part and the bracing part of the structural system. The seismic performance improvement obtained by means of TPMC, compared to Eurocode 8 provisions, is pointed out.

• 한국지진공학회논문집
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• 제1권3호
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• pp.37-44
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• 1997

본 논문에서는 지진하중을 받는 고층건물의 비탄성거동 특히, 층수에 따라 평면이 비대칭적으로 감소하여 발생하는 비틀림거동에 대하여 고찰하였다. 평면의 구조적 비대칭성에 의하여 발생하는 강성의 비대칭은 건물이 지진하중을 받을 때 횡변위 뿐만아니라 비틀림변형을 유발하게 된다. 이러한 비탄성 비틀림거동의 해석은 2차원모델로는 어려우므로 3차원해석이 요구된다. 본 논문에서는 102층의 비정형 초고층건물을 모델로 하여 내진설계규준에 의한 지진하중을 각 층에 가하여 하중의 크기를 증가시켜 정적 탄소성해석을 수행하였는데 비틀림에 의한 영향을 평가하기 위하여 비틀림을 제한한 모델과 그 거동을 비교분석하였다. 해석 결과에 따르면 비대칭건물의 탄소성 거동은 비틀림거동에 의하여 매우 큰 영향을 받는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제44권1호
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• pp.61-72
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• 2012

The paper is on contact analysis of a spherical ball with a deformable flat, considering the effect of tangent modulus on the contact parameters of a non-adhesive frictionless elastic-plastic contact. The contact analysis of this model has been carried out using analysis software Ansys and Abaqus. The contact parameters such as area of contact between two consecutive steps, volume of bulged material are evaluated from the formulated equations. The effect of the tangent modulus is considered for determining these parameters. The tangent modulus are accounted between 0.1E and 0.5E of materials E/Y value greater than 500 and less than 1750. Result shows that upto an optimal tangent modulus values the elastic core push up to the free surface in the flat. The simulation is also carried out in Abaqus and result provide evidence for the volume of bulged material in the contact region move up and flow into the free surface of the flat from the contact edge between the ball and flat. The strain energy of the whole model is varied between 20 to 40 percentage of the stipulated time for analysis.

• 한국생산제조학회지
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• 제20권6호
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• pp.679-684
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• 2011

Recently, STS 301L joints of side panels to frames for stainless steel rolling stock have been made out by using existing welding methods including Resistance Spot Welding, Laser Welding and Arc Welding. Most of the processes were jointed by spot welding because it is faster at welding and comparatively less expensive for investment in welding facilities than other methods. During spot welding, however, indentation of the metal surface was made due to pressure and melting property of welding. Moreover, since the melting metal was forced to periphery of the plate as indentation was made, sheet separation, which cracked apart between jointed sheets, was carried out. A slight deformation which resulted from sheet separation deteriorated the emotional quality of railway vehicles. This paper suggests that by processing conventional spot electrode tip appropriately, melting metal is able to push up around the processed part (Hollow Spot Electrode Tip) and prevent from being dislodged from first place to periphery. Consequently, sheet separation is remarkably decreased. Also, the emotional quality of appearance of stainless steel rolling stock is enhanced considerably.

• 한국화재소방학회논문지
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• 제22권5호
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• pp.29-34
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• 2008

본 연구에서는 대피자의 최적 배연조건 확립을 위하여 CFD모델을 이용한 수치해석을 통해 지하철 승강장 내에서의 화재 시 다양한 배연조건에서의 화재 위험성을 검토하였다. 결과로 스크린도어를 설치한 경우가 설치하지 않은 경우보다 온도의 상승폭이 최대 $65.37%{\sim}74.97%$ 낮게 나타났다. 또한 급기나 압인배기시 승강장에 난류가 발생함에 따라 온도 및 연기층이 교란되어 하락됨에 따라 탈출시 위험을 유발할 수 있는 것으로 판단되었다. 따라서 배연용량 및 승강장 공간 설정시 배연조건에 따른 화재 특성을 고려한 설계가 필요하다.

• Steel and Composite Structures
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• 제17권6호
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• pp.929-949
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• 2014

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

• Steel and Composite Structures
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• 제42권2호
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• pp.221-241
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• 2022

Perfobond rib connectors are widely used in composite structures to achieve the composite action between the steel and the concrete, and empirical expressions for their strength and secant stiffness have been obtained by numerical simulations or push-out tests. Since perfobond connections are generally in an elastic state in the service process and the structural analysis are always based on the elastic properties of the members, the secant stiffness is not applicable for the normal structural analysis. However, the tangent stiffness of perfobond connections has not been introduced in previous studies. Moreover, the perfobond connections are bearing tension and shear force simultaneously when the composite beams subjected to torque or local loads, but the current studies fail to arrive at the elastic stiffness considering the combined effects. To resolve these discrepancies, this paper investigates the initial elastic stiffness of perfobond connections under combined forces. The calculation method for the elastic stiffness of perfobond connections is analyzed, and the contributions of the perfobond rib, the perforating rebar and the concrete dowel are investigated. A finite element method was verified with a high value of correlation for the test results. Afterwards, parametric studies are carried out using the reliable finite element analysis to explore the trends of several factors. Empirical equations for predicting the initial elastic stiffness of perfobond connections are proposed by the numerical regression of the data extracted by parametric studies. The equations agree well with finite element analysis and test results, which indicates that the proposed empirical equations reflect a high accuracy for predicting the initial elastic stiffness of perfobond connections.