• Title/Summary/Keyword: Structural height

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Seismic Performance Evaluation of Steel Ordinary Moment Resisting Frames with Various Heights (다양한 높이를 갖는 철골 보통모멘트골조의 내진성능평가)

  • Baek, Seong-Jin;Kim, Tae-O;Han, Sang-Whan
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.33 no.5
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    • pp.3-10
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    • 2017
  • Steel ordinary moment frame(steel OMF) has been used as a seismic force resisting system in regions of low and moderate seismicity. In this study, the seismic performance of the steel OMFs with various heights in SDC $C_{max}$ was evaluated. For this purpose, nine steel OMFs were designed according to seismic design codes(ASCE/SEI 7-10, ANSI/AISC 341-10), and the collapse probability of these steel OMFs were estimated using FEMA P-695. The collapse probability of steel OMFs became larger with an increase in the height of frames. Some of steel OMFs designed according to current design codes did not satisfy the acceptance criteria specified in FEMA P-695.

The Structural Design of Tianjin Goldin Finance 117 Tower

  • Liu, Peng;Ho, Goman;Lee, Alexis;Yin, Chao;Lee, Kevin;Liu, Guang-lei;Huang, Xiao-yun
    • International Journal of High-Rise Buildings
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    • v.1 no.4
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    • pp.271-281
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    • 2012
  • Tianjin Goldin Finance 117 tower has an architectural height of 597 m, total of 117 stories, and the coronation of having the highest structural roof of all the buildings under construction in China. Structural height-width ratio is approximately 9.5, exceeding the existing regulation code significantly. In order to satisfy earthquake and wind-resisting requirements, a structure consisting of a perimeter frame composed of mega composite columns, mega braces and transfer trusses and reinforced concrete core containing composite steel plate wall is adopted. Complemented by some of the new requirements from the latest Chinese building seismic design codes, design of the super high-rise building in high-intensity seismic area exhibits a number of new features and solutions to professional requirements in response spectrum selection, overall stiffness control, material and component type selection, seismic performance based design, mega-column design, anti-collapse and stability analysis as well as elastic-plastic time-history analysis. Furthermore, under the prerequisite of economic viability and a series of technical requirements prescribed by the expert review panel for high-rise buildings exceeding code limits, the design manages to overcome various structural challenges and realizes the intentions of the architect and the client.

Two case studies on structural analysis of transmission towers under downburst

  • Yang, FengLi;Zhang, HongJie
    • Wind and Structures
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    • v.22 no.6
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    • pp.685-701
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    • 2016
  • Downbursts are of great harm to transmission lines and many towers can even be destroyed. The downburst wind field model by Chen and Letchford was applied, and the wind loads of two typical transmission towers in inland areas and littoral areas were calculated separately. Spatial finite element models of the transmission towers were established by elastic beam and link elements. The wind loads as well as the dead loads of conductors and insulators were simplified and applied on the suspension points by concentrated form. Structural analysis on two typical transmission towers under normal wind and downburst was completed. The bearing characteristics and the failure modes of the transmission towers under downburst were determined. The failure state of tower members can be judged by the calculated stress ratios. It shows that stress states of the tower members were mainly controlled by 45 degree wind load. For the inland areas with low deign wind velocity, though the structural height is not in the highest wind velocity zone of downburst, the wind load under downburst is much higher than that under normal wind. The main members above the transverse separator of the legs will be firstly destroyed. For the littoral areas with high deign wind velocity, the wind load under downburst is lower than under normal wind. Transmission towers are not controlled by the wind loads from downbursts in design process.

A new equation based on PGA to provide sufficient separation distance between two irregular buildings in plan

  • Loghmani, Adel;Mortezaei, Alireza;Hemmati, Ali
    • Earthquakes and Structures
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    • v.18 no.5
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    • pp.543-553
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    • 2020
  • Past earthquakes experience shows that serious damage or collapse of buildings have dramatically accrued when sufficient separation distance has not been provided between two adjacent structures. The majority of past studies related to the pounding topic indicate that obtaining the gap size between two buildings is able to prevent collision and impact hazards during seismic excitations. Considering minimization of building collisions, some relationships have been suggested to determine the separation distance between adjacent buildings. Commonly, peak lateral displacement, fundamental period and natural damping as well as structural height of two adjacent buildings are numerically considered to determine the critical distance. Hence, the aim of present study is to focus on all mentioned parameters and also utilizing the main characteristic of earthquake record i.e. PGA to examine the lateral displacement of irregular structures close to each other and also estimate the sufficient separation distance between them. Increasing and decreasing the separation distance is inherently caused economical problems due to the land ownership from a legal perspective and pounding hazard as well. Therefore, a new equation is proposed to determine the optimum critical distance. The accuracy of the proposed formula is validated by different models and various earthquake records.

Optimum study on wind-induced vibration control of high-rise buildings with viscous dampers

  • Zhou, Yun;Wang, DaYang;Deng, XueSong
    • Wind and Structures
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    • v.11 no.6
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    • pp.497-512
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    • 2008
  • In this paper, optimum methods of wind-induced vibration control of high-rise buildings are mainly studied. Two optimum methods, genetic algorithms (GA) method and Rayleigh damping method, are firstly employed and proposed to perform optimum study on wind-induced vibration control, six target functions are presented in GA method based on spectrum analysis. Structural optimum analysis programs are developed based on Matlab software to calculate wind-induced structural responses. A high-rise steel building with 20-storey is adopted and 22 kinds of control plans are employed to perform comparison analysis to validate the feasibility and validity of the optimum methods considered. The results show that the distributions of damping coefficients along structural height for mass proportional damping (MPD) systems and stiffness proportional damping (SPD) systems are entirely opposite. Damping systems of MPD and GAMPD (genetic algorithms and mass proportional damping) have the best performance of reducing structural wind-induced vibration response and are superior to other damping systems. Standard deviations of structural responses are influenced greatly by different target functions and the influence is increasing slightly when higher modes are considered, as shown fully in section 5. Therefore, the influence of higher modes should be considered when strict requirement of wind-induced vibration comfort is needed for some special structures.

Design of diffusers in consideration of scattering and diffusion characteristics (확산 지향성을 고려한 확산체의 설계)

  • Kim, Yong-Hee;Kim, Jae-Ho;Kim, Jeong-Jun;Jeon, Jin-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.21-24
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    • 2008
  • This study proposes a optimized shape of diffuser profile through investigating the scattering and diffusion characteristics of diffusers. The scattering coefficient according to ISO 17497-1 evaluates uniformity of reverberant sound field of late reflections, while the diffusion coefficient according to AES-4id-2001 evaluates polar response of early reflections. Thus both scattering and diffusion characteristics should contribute to design shape of diffusers to maximize physical performance. To find out design method, the previous results on hemisphere diffusers are reviewed. The frequency characteristics of scattering coefficients depended on the structural height of the diffusers, while amount of scattering coefficients depended on the surface coverage density of the diffusers. However absorptive properties also increased with augment of surface coverage density, thus optimum coverage density should be considered. For the directional diffuser, three types of 2D-diffusers are proposed; semicylinder of h=5mm, semi-truncated cone of h=5-25mm and semicylinder of h=25mm. As results, diffusers with the maximum height of 25mm show the highest scattering coefficients, while diffuser of h=5mm shows high scattering coefficients only at the high-frequency bands. Diffusion coefficient will be investigated for diffusive properties of the early reflection.

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Distribution of Optimum Yield-Strength and Plastic Strain Energy Prediction of Hysteretic Dampers in Coupled Shear Wall Buildings

  • Bagheri, Bahador;Oh, Sang-Hoon;Shin, Seung-Hoon
    • International journal of steel structures
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    • v.18 no.4
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    • pp.1107-1124
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    • 2018
  • The structural behavior of reinforced concrete coupled shear wall structures is greatly influenced by the behavior of their coupling beams. This paper presents a process of the seismic analysis of reinforced concrete coupled shear wall-frame system linked by hysteretic dampers at each floor. The hysteretic dampers are located at the middle portion of the linked beams which most of the inelastic damage would be concentrated. This study concerned particularly with wall-frame structures that do not twist. The proposed method, which is based on the energy equilibrium method, offers an important design method by the result of increasing energy dissipation capacity and reducing damage to the wall's base. The optimum distribution of yield shear force coefficients is to evenly distribute the damage at dampers over the structural height based on the cumulative plastic deformation ratio of the dissipation device. Nonlinear dynamic analysis indicates that, with a proper set of damping parameters, the wall's dynamic responses can be well controlled. Finally, based on the total plastic strain energy and its trend through the height of the buildings, a prediction equation is suggested.

Structural System Selection and Highlights of Changsha IFC T1 Tower

  • Jianlong, Zhou;Daoyuan, Lu;Liang, Huang;Jun, Ji;Jun, Zhu;Jingyu, Wang
    • International Journal of High-Rise Buildings
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    • v.3 no.2
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    • pp.99-106
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    • 2014
  • This paper presents the determination of the structural system of the Changsha IFC T1 tower with 452 m in architectural height and 440.45 m in structural height. Sensitivity analyses are carried out by varying the location of belt trusses and outriggers. The enhancement of seismic capacity of the outer frame by reasonably adjusting the column size is confirmed based on parametric studies. The results from construction simulation including the non-load effect of structures demonstrate that the deformation of vertical members has little effect on the load-bearing capacity of belt trusses and outriggers. The elastoplastic time-history analysis shows that the overall structure under rare earthquake load remains in an elastic state. The influence of the frame shear ratio and frame overturning moment ratio on the proposed model and equivalent mega column model is investigated. It is found that the frame overturning moment ratio is more applicable for judging the resistance of the outer frame against lateral loads. Comparison is made on the variation of these two effects between a classical frame-core tube-outrigger structure and a structure with diagonal braces between super columns under rare earthquakes. The results indicate that plasticity development of the top core cube of the braced structure may be significantly improved.

Estimation of fundamental natural period of vibration for reinforced concrete shear walls systems

  • Shatnawi, Anis S.;Al-Beddawe, Esra'a H.;Musmar, Mazen A.
    • Earthquakes and Structures
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    • v.16 no.3
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    • pp.295-310
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    • 2019
  • This study attempts to develop new simplified approximate formulas to predict the fundamental natural periods of vibration (T) for bearing wall systems engaged with special reinforced concrete shear walls (RCSW) under seismic loads. Commonly, seismic codes suggested empirical formulas established by regression analysis of measured T for buildings during earthquake motions. These formulas depend on structure type, building height, number, height and length of SW, and ratio of SW area to base area of structure. In this study, a parametric investigation is performed for T of 110 selected models of bearing RCSW systems with varying structural height, configuration of horizontal plans including building width, number and width of bays, presence of middle corridors and core SWs. For this purpose, a 3D non-linear response time history (TH) analysis is implemented using ETABS v16.2.1. New formulas to estimate T are anticipated and compared with those obtained from formulas of IBC 2012 and ASCE/SEI 7-10. Moreover, the study examines responses of an arbitrarily two selected test model of 60 m and 80 m in height with presence of SWs having middle corridors. It is observed that the performance of the tested buildings is different through arising of considerable errors when using codes' formulas for estimating T. Accordingly, using the present proposed formulas exhibits more reasonable and safer design compared to codes' formulas. The results showed that equitable enhancement is promising to improve T formulas approaching enhanced and accurate estimation of T with reliable analysis, design, and evaluation of bearing RCSW systems.

The Nonlinear Behavior Characteristics of the 3D Mixed Building Structures with Variations in the Lower Stories (입체 복합구조물의 하부골조 층수 변화에 따른 비선형 거동특성)

  • 강병두;전대한;김재웅
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.1
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    • pp.55-62
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    • 2002
  • The upper wall-lower frame structures(mixed building structures) are usually composed of shear wall structure in the upper part of structure which is used as residential space and frame structure in the lower part of structure which is used as commercial space centering around the transfer system in the lower part of structure. These structures are characteristics of stiffness irregularity, mass irregularity, and vertical geometric irregularity. The purpose of this study is to investigate the nonlinear response characteristics and the seismic capacity of mixed building structures when the number of stories in the lower frame is varied. The conclusions of this study are following. 1) As the result of push-over analysis of structure such as roof drift(i.e. roof displacement/structural height) and base shear coefficient, when the stories of lower frame system are increased, base shear coefficient is decreased, but roof drift is increased. 2) According to an increase in stories of the lower fame, story drift and ductility ratio of upper wall system are decreased and behavior of upper wall system is closed to elastic. 3) When the stories of lower frame system are increased, the excessive story drift is concentrated on the lower frame system.