• Structural Engineering and Mechanics
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• v.81 no.1
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• pp.39-50
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• 2022

Layer separation (delamination) is an essential threat to fiber-reinforced polymer (FRP) plates under dynamic, static, and fatigue loads. Under compressive load, the growth of delamination will lead to structural instability. The aim of this paper is to present a method using shape memory alloy (SMA) stitches to suppress the delamination growth in a FRP plate and to improve the buckling behavior of the plate with a rectangular hole. The present paper is divided into two parts. Firstly, a closed-form (CF) formulation for evaluating the buckling load of the FRP plate is presented. Secondly, the finite element method (FEM) will be employed to calculate the buckling loads of the plates which serves to validate the results obtained from the closed-form method. The novelty of this work is the development of the closed-form solution using the p-Ritz energy approach regarding the stress-dependent phase transformation of SMA to trace the equilibrium path. For the FEM, the Lagoudas constitutive model of the SMA material is implemented in FORTRAN programming language using a user material subroutines (VUMAT). The model is simulated in ABAQUS/Explicit solver due to the nature of the loading type. The cohesive zone model (CZM) is applied to simulate the delamination growth.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.376-381
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• 2019

In this work, we evaluated the structural, electrical and optical properties of $Ge_8Sb_2Te_{11}$ and Cu-doped $Ge_8Sb_2Te_{11}$ thin films prepared by rf-magnetron reactive sputtering. The 200-nm-thick deposited films were annealed in a range of $100{\sim}400^{\circ}C$ using a furnace in an $N_2$ atmosphere. The amorphous-to-crystalline phase changes of the thin films were investigated by X-ray diffraction (XRD), UV-Vis-IR spectrophotometry, a 4-point probe, and a source meter. A one-step phase transformation from amorphous to face-centered-cubic (fcc) and an increase of the crystallization temperature ($T_c$) was observed in the Cu-doped film, which indicates an enhanced thermal stability in the amorphous state. The difference in the optical energy band gap ($E_{op}$) between the amorphous and crystalline phases was relatively large, approximately 0.38~0.41 eV, which is beneficial for reducing the noise in the memory devices. The sheet resistance($R_s$) of the amorphous phase in the Cu-doped film was about 1.5 orders larger than that in undoped film. A large $R_s$ in the amorphous phase will reduce the programming current in the memory device. An increase of threshold voltage ($V_{th}$) was seen in the Cu-doped film, which implied a high thermal efficiency. This suggests that the Cu-doped $Ge_8Sb_2Te_{11}$ thin film is a good candidate for PRAM.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.18-28
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• 2011

This study is aimed at the improvement of administrative operations of landscape design competitions and qualitative enhancement of design quality by mutually comparing the guidelines and entry plans. The case targeted for the current study is landscape design proposals for the Seoul Hangdong Bogeumjari Housing District recently launched within a greenbelt zone in the outskirts of Seoul. The study examines from a critical perspective the design guidelines and the contents of the three winning design proposals with a focus on whether or not they have reflected the guidelines. It was observed that many provisions of the principles and conceptual guidelines which serve as clues to the designs for winning designs proposals show the direction in which the project is to be headed It was also observed that the provisions and the way they are expressed are intertwined, while, at the same time, the guidelines were not organized or developed in an orderly manner. Such a structural pattern of the guidelines is linked to the aspects of the contents of the winning design proposals as described in the following. It is observed that guidelines related to the direction in which the design to be headed are so regulatory and lengthy that they are overly standardized. This could make it difficult to read the possibility of the alternative shifts in the winning design proposals. At the same time, the attributes of winning design proposals themselves, which require observable discriminatory superiority, could serve as a factor causing excess of meanings by jumping on the bandwagon of naming. On the contrary, where autonomy of design is guaranteed or no guidelines are provided for the winning design proposals, discriminatory differences were observed, thereby making it easy to measure them This illustrates well that guidelines and structural format should be provided through a separate undertaking that has taken into careful consideration environmental traits of the site in question, objectives required and so forth.

• Journal of the Korea Institute of Building Construction
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• v.24 no.4
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• pp.507-515
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• 2024

Recent advancements in Building Information Modeling(BIM) have significantly impacted the construction industry, driving competitiveness and innovation. However, rebar construction, a critical component influencing project quality and cost, has lagged behind in BIM adoption. Traditional methods relying heavily on 2D drawings for rebar detailing have hindered efficiency and introduced potential errors. This paper presents a novel system designed to automate the detailed modeling of rebar, thereby promoting BIM integration within rebar construction and optimizing construction management processes. The system leverages confirmed structural drawings from the post-structural design phase to automatically generate intricate rebar models for columns and beams. To ensure adherence to domestic structural design standards, the system is developed using C# programming language and the Revit API. By automating rebar modeling, this system aims to minimize human error, reduce labor-intensive tasks, and enhance overall rebar construction efficiency through the effective utilization of generated rebar model data.

• Earthquakes and Structures
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• v.19 no.1
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• pp.17-28
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• 2020

In this paper, a modified and improved seismic isolation system called suspension columns for seismic isolation was investigated. An experimental study of the proposed isolation method, together with theoretical and numerical analyses, has thoroughly been conducted. In the proposed method, during the construction of the foundation, some cavities are created at the position of the columns inside the foundation and the columns are placed inside the cavities and hanged from the foundation by flexible cables rather being directly connected to the foundation. Since the columns are suspended and due to the gap between the columns and walls of the cavities, the structure is able to move freely to each side thus, the transmitted seismic actions are reduced. The main parameter of this isolation technique is the length of the suspension cable. As the cable length is changed, the natural frequency of the structure is also changed, thus, the desired frequency can be achieved by means of an appropriate cable length. As the experimental phase of the study, a steel frame structure with two floors was constructed and subjected to the acceleration of three earthquakes using a shaking table with different hanging cable lengths. The structural responses were recorded in terms of acceleration and relative displacement. The experimental results were compared to the theoretical and numerical ones, obtained from the MATLAB programming and the finite element software ABAQUS, showing a suitable agreement between them. The results confirm the effectiveness of the proposed isolation method in reducing the seismic effects on the structure.

• International Journal of High-Rise Buildings
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• v.7 no.2
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• pp.145-151
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• 2018

Newly-designed high-rise buildings, both in China and abroad, have demonstrated new innovations from the creative concept to the creative method. from the creative concept to the creative method. At the same time, digital technology has enabled more design freedom in the vertical dimension. "Twisting" has gradually become the morphological choice of many city landmark buildings in recent years. The form seems more likely to be driven by the interaction of aesthetics and structural engineering. Environmental performance is often a secondary consideration; it is typically not simulated until the evaluation phase. Based on the research results of "DigitalFUTURE Shanghai 2017 Workshop - Wind Tunnel Visualization", an approach that can be employed by architects to design environmental-performance buildings during the early stages has been explored. The integration of a dynamic form-finding approach (DFFA) and programming transforms the complex relationship between architecture and environment into a dialogue of computer language and dynamic models. It allows the design to focus on the relationship between morphology and the surrounding environment, and is not limited to the envelope form itself. This new concept of DFFA in this research consists of three elements: 1) architectural form; 2) integration of wind tunnel and dynamic models; and 3) environmental response. The concept of wind tunnel testing integrated with a dynamic model fundamentally abandons the functional definition of the traditional static environment simulation analysis. Instead it is driven by integral environmental performance as the basic starting point of morphological generation.