• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.1-4
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• 2006

Ku band satellite signal repeating technology just altering a polarization of the repeated signal is applicable for any kind of satellite broadcasting service in geographically shadowed area due to high-rise buildings, trees, and so on. This paper focuses on the design of high polarization discrimination antenna satisfying polarization characteristics with respect to field pattern and frequency band. Designed antenna for the enhancement of axial ratio and polarization discrimination characteristic shows good performance for satellite broadcasting service repeating system.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.377-386
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• 2020

Beginning a few decades ago, Baku, the capital city of Azerbaijan, has experienced a dramatic construction boom that is revitalizing its skyline. The expansive growth looks to uphold the historic past of Baku as a focal point within the Caspian Sea Region while also evoking aspirations for a city of the future. With superstructure complete and interiors progressing, the Ministry of Taxation (MOT) tower is the latest addition to the city, with its stacked cubes twisting above a multi-level podium at the base. Each cube is separated by column-free green roof terraces, creating unique parametric reveals of the developing surroundings. Aside from MOT's stunning shape, its geolocation resulted in unusually high wind loads coupled with high seismic hazards for a tower of its height. In addition, limitations on possible structural systems required stepping away from a typical prescriptive code-based approach into one that utilized Performance-Based Design (PBD) methods. This paper presents the numerous structural challenges and innovations that allowed the design of a new icon to be realized.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.111-112
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• 2022

Lightweight aggregate is a porous material that has a lower density than natural aggregate and is a lightweight construction material. Lightweight Aggregate has a suitable purpose because it is effective in reducing the heavy unit mass in high-rise buildings. However, since lightweight aggregate has weak strength and high water absorption compared to natural aggregate, it is difficult to control the quality of concrete. Although lightweight aggregate has disadvantages such as high water absorption, it is expected that the demand for lightweight aggregate concrete will continue to use in the future because the advantage of being able to reduce the weight of concrete is greater. In this study, we conducted an experimantal study on the compressive strength property of cement matrix according to the type of lightweight aggregate.

• International Journal of High-Rise Buildings
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• v.13 no.2
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• pp.187-194
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• 2024

The 53-meter tall Albizzia Tower is a white, mineral building with a mixed concrete and wood structure. It harmoniously interacts with the high rises of La Confluence. Its base is largely open, in direct relation to the public space. The spaces are mutable, reversible, moldable thanks to a streamlined structure: posts, beams in glued laminated wood, with posts pushed back on the facade to facilitate the layout of office and housing floors, CLT floors with a span of 7 meters.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.4
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• pp.90-104
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• 2007

Landmarks like high-rise building are one of the important elements for the enhancement of city identity and provides the hierarchy of city streets, playing a central and symbolic role in cities. Research on physical attribute of landmarks, such as height, distance, location and shape, which are suitable for a city scale, can help a city create a distinct image and maintain comprehensible structure. To achieve this purpose, it is necessary to understand the spatial and cognitive characteristics of a landmark for the establishment and management of it. The results of this study can be summarized as follows: 1. The level of representativeness of a landmark increases in proportion to the degree of cognitive intensity on it. The relation between representativeness and cognitive intensity can be explained as the log-function as follows: Log(the number of people who respond "It has representativeness")=$-1.2579+1.5908{\times}$(cognitive intensity); 2. There are a few differences based on the attributes of respondents: while gender has no distinct influence, residential period and age show statistically meaningful influence on cognitive intensity of a vertical landmark Cognitive intensity of an individual landmarks especially, differs according to the class of main users. Because of frequent changes in occupation or employment, respondents consider the distance from a residential area more important than the distance from a working area in evaluating cognitive intensity of landmarks; 3. landmark can be classified into two kinds: a district landmark and an urban landmark A district landmark is closely connected with physical attributes of the landmark itself, such as distance, size and height. An urban landmark is mainly related to cognitive attributes such as the image and identity of a city as a whole. As a result, the landmark analysis data in this research provides spatial order and identity in a city. It is difficult to establish and reinforce the image of a city as a single element ike a landmark. However, withy steady follow-up research, this study could be seen as a systematic and logical model to improve urban landscape and image.

• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.425-430
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• 2022

Concrete used for the foundation of high-rise buildings is often placed through in an integrated pouring to ensure construction efficiency and quality. However, if concrete is placed integrally, there is a high risk of temperature cracking during the hydration reaction, and it is necessary to determine the optimal mixing design of high-performance, high-durable concrete through the replacement of the admixture. In this study, experiments on salt damage, carbonation, and sulfate were conducted on the specimen manufactured from the optimal high-performance low-heating concrete combination determined in the author's previous study. The resistance of the cement matrix to chlorine ion diffusion coefficient, carbonation coefficient, and sulfate was quantitatively evaluated. In the terms of compression strength, it was measured as 141% compared to the structural design standard of KCI at 91 days. Excellent durability was expressed in carbonation and chlorine ion diffusivity performance evaluation. In particular, the chlorine ion diffusion coefficient, which should be considered the most strictly in the marine environment, was measured at a value of 4.09×E-12m²/y(1.2898×E-10m²/s), and is expected to be used as a material property value in salt damage durability analysis. These results confirmed that the latent hydroponics were due to mixing of the admixture and high resistance was due to the pozzolane reaction.

• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.287-298
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• 2018

High strength steels have been widely applied in recent years due to high strength and good working performance. When subjected to fire conditions, the strength and elastic modulus of high strength steels deteriorate significantly and hence the load bearing capacity of structures reduces at elevated temperatures. The reduction factors of mechanical properties of high strength steels are quite different from mild steels. Therefore, the fire design methods deduced from mild steel structures are not applicable to high strength steel structures. In recent ten years, the first author of this paper has carried out a lot of fundamental research on fire behavior of high strength steels and structures. Summary of these research is presented in this paper, including mechanical properties of high strength steels at elevated temperature and after fire exposure, creep response of high strength steels at elevated temperature, residual stresses of welded high strength steel member after fire exposure, fire resistance of high strength steel columns, fire resistance of high strength steel beams, local buckling of high strength steel members, and residual strength of high strength steel columns after fire exposure. The results show that the mechanical properties of high strength steel in fire condition and the corresponding fire resistance of high strength steel structures are different from those of mild steel and structures, and the fire design methods recommended in current design codes are not applicable to high strength steel structures.

• Earthquakes and Structures
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• v.5 no.5
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• pp.499-526
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• 2013

Seismic isolation is an effective method for the protection of buildings and their contents during strong earthquakes. This research work aims to assess the appropriateness of the linear and nonlinear models that can be used in the analysis of typical low-rise base isolated steel buildings, taking into account the inherent nonlinearities of the isolation system as well as the potential nonlinearities of the superstructure in case of strong ground motions. The accuracy of the linearization of the isolator properties according to Eurocode 8 is evaluated comparatively with the corresponding response that can be obtained through the nonlinear hysteretic Bouc-Wen constitutive model. The suitability of the linearized model in the determination of the size of the required seismic gap is assessed, under various earthquake intensities, considering relevant methods that are provided by building codes. Furthermore, the validity of the common assumption of elastic behavior for the superstructure is explored and the alteration of the structural response due to the inelastic deformations of the superstructure as a consequence of potential collision to the restraining moat wall is studied. The usage of a nonlinear model for the isolation system is found to be necessary in order to achieve a sufficiently accurate assessment of the structural response and a reliable estimation of the required width of the provided seismic gap. Moreover, the simulations reveal that the superstructure's inelasticity should be taken into account, especially if the response of the structure under high magnitude earthquakes is investigated. The consideration of the inelasticity of the superstructure is also recommended in studies of structural collision of seismically isolated structures to the surrounding moat wall, since it affects the response.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1045-1075
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• 2016

Shallow footings are one of the most common types of foundations used to support mid-rise buildings in high risk seismic zones. Recent findings have revealed that the dynamic interaction between the soil, foundation, and the superstructure can influence the seismic response of the building during earthquakes. Accordingly, the properties of a foundation can alter the dynamic characteristics (natural frequency and damping) of the soil-foundation-structure system. In this paper the influence that shallow foundations have on the seismic response of a mid-rise moment resisting building is investigated. For this purpose, a fifteen storey moment resisting frame sitting on shallow footings with different sizes was simulated numerically using ABAQUS software. By adopting a direct calculation method, the numerical model can perform a fully nonlinear time history dynamic analysis to realistically simulate the dynamic behaviour of soil, foundation, and structure under seismic excitations. This three-dimensional numerical model accounts for the nonlinear behaviour of the soil medium and structural elements. Infinite boundary conditions were assigned to the numerical model to simulate free field boundaries, and appropriate contact elements capable of modelling sliding and separation between the foundation and soil elements are also considered. The influence of foundation size on the natural frequency of the system and structural response spectrum was also studied. The numerical results for cases of soil-foundation-structure systems with different sized foundations and fixed base conditions (excluding soil-foundation-structure interaction) in terms of lateral deformations, inter-storey drifts, rocking, and shear force distribution of the structure were then compared. Due to natural period lengthening, there was a significant reduction in the base shears when the size of the foundation was reduced. It was concluded that the size of a shallow foundation influences the dynamic characteristics and the seismic response of the building due to interaction between the soil, foundation, and structure, and therefore design engineer should carefully consider these parameters in order to ensure a safe and cost effective seismic design.

• Steel and Composite Structures
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• v.37 no.1
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• pp.91-98
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• 2020

Steel plate shear walls are recently used as efficient seismic lateral resisting systems. These lateral resistant structures are implemented to provide more strength, stiffness and ductility in limited space areas. In this study, the seismic behavior of the multi-story steel frames with steel plate shear walls are investigated for buildings with 4, 8, 12 and 16 stories using verified computational modeling platforms. Different number of steel moment bays with distinctive lengths are investigated to effectively determine the deflection amplification factor for low-rise and high-rise structures. Results showed that the dissipated energy in moment frames with steel plates are significantly related to the inside panel. It is shown that more than 50% of the dissipated energy under various ground motions is dissipated by the panel itself, and increasing the steel plate length leads to higher energy dissipation capability. The deflection amplification factor is studied in details for various verified parametric cases, and it is concluded that for a typical multi-story moment frame with steel plate shear walls, the amplification factor is 4.93 which is less than the recommended conservative values in the design codes. It is shown that the deflection amplification factor decreases if the height of the building increases, for which the frames with more than six stories would have less recommended deflection amplification factor. In addition, increasing the number of bays or decreasing the steel plate shear wall length leads to a reduction of the deflection amplification factor.