• Earthquakes and Structures
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• v.6 no.2
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• pp.163-179
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• 2014

Dynamic test with scaled model of a group of intake towers was performed to study the dynamic interaction between water and towers. The test model consists of intake tower or towers, massless foundation near the towers and part of water to simulate the dynamic interaction of tower-water-foundation system. Models with a single tower and 4 towers were tested to find the different influences of the water on the tower dynamic properties, seismic responses as well as dynamic water-tower interaction. It is found that the water has little influence on the resonant frequency in the direction perpendicular to flow due to the normal force transfer role of the water in the contraction joints between towers. By the same effect of the water, maximum accelerations in the same direction on 4 towers tend to close to each other as the water level increased from low to normal level. Moreover, the acceleration responses of the single tower model are larger than the group of towers model in both directions in general. Within 30m from the surface of water, hydrodynamic pressures were quite close for a single tower and group of towers model at two water levels. For points deeper than 30m, the pressures increased about 40 to 55% for the group of towers model than the single tower model at both water levels. In respect to the pressures at different towers, two mid towers experienced higher than two side towers, the deeper, the larger the difference. And the inside hydrodynamic pressures are more dependent on ground motions than the outside.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.135-140
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• 2019

Lattice towers and tubular steel poles have been commonly used for electrical power transmission in Korea. They are durable, structurally stable, simple and can easily be constructed in limited spaces. However, residents are opposed to construct transmission lattice towers in their areas because they are not visually attractive, and electrical field occur at the transmission lines. Underground transmissions have been used instead of the traditional towers to resolve these problems, however they are not cost effective to construct and run. Therefore, we have developed eco-friendly towers that are more attractive, well blending into the surrounding environment, and much more economical than underground transmissions. There are four categories of the eco-friendly electric transmission towers about design aspects. Firstly, there is decoration type such as tree tower and ensemble tower. Tree tower looks like actual trees with leaves and branches so it blends into surroundings. Ensemble towers were designed after pair of crane birds. Those towers have decoration features and art works. Structural examination and manufacturing this type would be very similar to the conventional transmission towers. Secondly, there is arm design type such as traditional tower. Design features are added to the existing towers. As partial design can be adoptable on these types, it can easily meet height regulations and attach to conventional lattice towers and tubular steel poles. Also, these towers are more economical than others. Third category is multipurpose type such as Sail Tower. These towers have simple pole or tubular structure with features which can be used as information message board, public relations and much more. This type will face greater wind pressure because of the area of the board, also visibility must take into consideration. Lastly, there is moulding type such as arc pylon. It is different shape to the conventional towers - lattice towers and tubular steel poles. Dramatic design changes have been adapted - from a hard and static tower to a soft and curved tower. These towers will well stand out in the field. However, structural examination and manufacturing this type would be difficult and costly. Also certain towers of this type would require scaffolding or false work to construct, which will result in limitations of the construction area. This paper shows KEPCO 154 kV Sail tower in detail. KEPCO 154 kV Sail tower that is included in fabrication of sample tower and tower testing has developed and the results are presented in this paper. We hope that sail tower is also considered as a solution to have public acceptance or to create a familiar atmosphere among towers and people in coastal area.

• 전기의세계
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• v.16 no.5
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• pp.37-50
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• 1967

The economical design of steel towers fortrausmission line. This study has been made on the design criteria of steel towers for power trasmission line adopted in the United States of America, France, Japan and Korea in order to find out any access to design the economical steel twers in Korea following to our own climate conditions. As the result of this study, involved in this description. Writer belive that the weight of steel towers can be saved by 10% to 20% approximately on the steel towers which will be constructed in the near future in Korea, by the possibility of reducing the design wind pressures on towers and cables in those areas of inland of Korea, the increase of number of standard towers from four types to five, the adoption of comparative narrower base towers than those in past practice and improvement on the assumption of manimum delection angle of suopension type insulator strings.

• International Journal of High-Rise Buildings
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• v.7 no.3
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• pp.197-214
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• 2018

Tall buildings which began from about 40 m tall office towers in the late $19^{th}$ century have evolved into mixed-use megatall towers over 800 m. It is expected that even mile-high towers will soon no longer be a dream. Structural systems have always been one of the most fundamental technologies for the dramatic developments of tall buildings. This paper presents structural systems employed for the world's tallest buildings of different periods since the emergence of supertall buildings in the early 1930s. Further, structural systems used for today's extremely tall buildings over 500 m, such as core-outrigger, braced mega-tube, mixed, and buttressed core systems, are reviewed and their performances are studied. Finally, this paper investigates the potential of superframed conjoined towers as a viable structural and architectural solution for mile-high and even taller towers in the future.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.63-66
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• 2018

Lattice towers and tubular steel poles have been commonly used for electrical power transmission in Korea as well as the other countries. They are durable, structurally stable, simple and can easily be constructed in limited spaces. However, residents are opposed to construct transmission lattice towers in their areas because they are not visually attractive, and electrical field occur at the transmission lines. Underground transmissions have been used instead of the traditional towers to resolve these problems, however they are not cost effective to construct and run. Therefore, we have developed compact towers that are more attractive, well blend into the surrounding environment and much more economical than underground transmissions. This paper shows the design of a compact towers with insulation arm, in order to reduce the height of tower and the separation between phases. The compact tower can be installed in a narrow right-of-way. Insulation arms are easily applied to lattice and steel tubular towers instead of steel arms. Compact towers with insulation arm are also considered as a solution to have public acceptance or to create a familiar atmosphere among towers and people. Compact tower compared with a conventional tower, insulation arms reduces the width and height of the tower by 20% and 15% respectively.

• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.387-396
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• 2020

While tall buildings are an essential building type to accommodate an ever-growing urban population, as buildings become taller and taller, many design challenges arise. As floor spaces are repeated vertically, the occupants' natural horizontal circulation-based social interactions are limited. As buildings become ever taller, safe evacuation to the ground level becomes more challenging in emergencies. With respect to safety as well as serviceability, one of the most fundamental design challenges of exceedingly tall buildings is their structural systems that make the physical existence of tall buildings possible. While many different design solutions can be sought to resolve these issues as well as other design challenges of extremely tall buildings, this paper investigates the potential of conjoined towers to create more livable and sustainable vertical environments. Emphasis is placed on the social and structural capabilities of conjoined towers in providing enhanced social interactions and more efficient ultra-tall structures. The related brief history of conjoined towers is presented. To understand their current status, contemporary design practices of conjoined towers are discussed. Lastly, a new concept of superframed conjoined towers developed for exceedingly tall building complexes is introduced through design studies. Though envisioning future tall buildings is challenging, conjoined towers can be among the strong candidates toward more livable and sustainable vertical urbanism.

• Structural Engineering and Mechanics
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• v.73 no.5
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• pp.487-500
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• 2020

Stiffeners can be utilised to enhance the strength of thin-walled wind turbine towers in engineering practise, thus, structural performance of wind turbine towers by means of different stiffening schemes should be compared to explore the optimal structural enhancement method. In this paper two alternative stiffening methods, employing horizontal or vertical stiffeners, for steel tubular wind turbine towers have been studied. In particular, two groups of three wind turbine towers of 50m, 150m and 250m in height, stiffened by horizontal rings and vertical strips respectively, were analysed by using FEM software of ABAQUS. For each height level tower, the mass of the stiffening rings is equal to that of vertical stiffeners each other. The maximum von Mises stresses and horizontal sways of these towers with vertical stiffeners is compared with the corresponding ring-stiffened towers. A linear buckling analysis is conducted to study the buckling modes and critical buckling loads of the three height levels of tower. The buckling modes and eigenvalues of the 50m, 150m and 250m vertically stiffened towers were also compared with those of the horizontally stiffened towers. The numbers and central angles of the vertical stiffeners are considered as design variables to study the effect of vertical stiffeners on the structural performance of wind turbine towers. Following an extensive parametric study, these strengthening techniques were compared with each other and it is obtained that the use of vertical stiffeners is a more efficient approach to enhance the stability and strength of intermediate and high towers than the use of horizontal rings.

• Smart Structures and Systems
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• v.21 no.1
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• pp.99-111
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• 2018

Wind induced large bending oscillation amplitudes in tall and slender telecommunication steel towers may lead to precocious fatigue cracks and consequent risk of collapse of these structures, many of them installed in rural areas alongside highways and in highly populated urban areas. Varying stress amplitudes at hot spots may be attenuated by means of passive control mechanical devices installed in the tower. This paper gives an account of both mathematical-numerical model and the technique applied to design and evaluate the performance of a double controller installed in existing towers which is composed by a nonlinear pendulum and a novel type of passive controller described herein as a planar motion disk mounted on shear springs. Results of experimental measurements carried out on two slender tubular steel towers under wind action demonstrate the efficiency of the double controllers in attenuating the towers bending oscillation amplitudes and consequent stress amplitudes extending the towers fatigue life.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.273-274
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• 2013

Recently, as offshore wind towers are developed, the size of wind towers have become larger and larger, and offshore wind towers are exposed to various external forces such as wave and current compared with onshore wind towers. Thus, the stability of offshore wind towers is more required than onshore wind towers. In this study, when the wind celerity of 60m/s blows to the cylinder, cone, and stair typed towers, the wind and wave forces on foundation are calculated by p-y relation.

• International Journal of High-Rise Buildings
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• v.10 no.3
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• pp.179-191
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• 2021

Tall buildings have generally been developed as solo towers. With the increase of the heights of tall buildings from about 10-story buildings to supertall and megatall buildings, their structural systems have evolved from interior structures to exterior structures and combined/mixed systems. This paper reviews structural systems developed for solo supertall and megatall buildings and discusses the challenges they face in terms of structural performance and architectural design as the building heights are ever increased. As a viable and more sustainable design alternative to extremely tall solo towers, superframed conjoined towers are presented. Their structural performances are investigated in comparison with solo tower structures. Further, architectural potentials of superframed conjoined towers are explored through design studies.