Design Of Super-tall Buildings Research Articles

Study on Wind Load Characteristics of a Super Tall Building Based on Numerical Simulation

This paper present some selected numerical results of a typical super-tall building based on a new Large Eddy Simulation scheme. The spatial correlation of local wind forces were presented and discussed in detail. The probabilistic characteristics of fluctuating wind loads were evaluated. Furthermore, the along-wind and across-wind spectral characteristics were studied and compared with the von Karman spectrum. The output of this study is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.

Extreme Value Distribution and Peak Factor of Crosswind Response of Flexible Structures with Nonlinear Aeroelastic Effect

The crosswind response at the vicinity of vortex lock-in wind speed becomes an increasing concern in structural design of super tall buildings and other dynamically sensitive structures. Because of nonlinear aeroelastic effect of vortex shedding, the extreme value distribution and peak factor of crosswind response are distinctly different from traditional wind-induced stochastic buffeting response. This study establishes an effective approach for predicting extreme value distribution and peak factor of crosswind response of flexible structures on the basis of an improved understanding of the underlying mechanism. It is pointed out that the improved extreme theory of Gaussian processes with consideration of narrow-band feature cannot interpret the extreme crosswind response. This study, at the first time, reveals that the unique characteristics of extreme value distribution of crosswind response is primarily attributed to its hardening non-Gaussian distribution. An extensive analysis of simulated crosswind response illustrates that the extreme value distribution and peak factor can be estimated from those of an underlying Gaussian process based on the translation process theory. The translation function between non-Gaussian crosswind response and Gaussian process can be expressed in terms of Hermite polynomial model based on the first four statistical moments or quantified by mapping of cumulative distribution functions and curve fitting. Closed-form formulations are developed for calculating Hermite translation model coefficients, which permits the estimation of extreme value distribution and peak factor directly using the response kurtosis and bandwidth parameter. The characteristics of crosswind response and the proposed approach are also validated using full-scale vibration measurements of a wind-excited traffic-signal-support structure. This study not only clarified the mechanism responsible for the unique extreme value distribution of crosswind response with nonlinear aeroelastic effect but also established an effective simple approach for its estimation using the characteristics of response process.

Development of a simplified model and seismic energy dissipation in a super-tall building

The seismic design of super-tall buildings has become an important research topic in earthquake engineering. Limited research has been conducted on the distribution of plastic energy dissipation among the different components of super-tall buildings when subjected to strong earthquakes. A simplified two-dimensional (2D) nonlinear model is developed based on the analysis of Shanghai Tower, an actual super-tall building with a total height of 632m. The accuracy of the simplified model is validated by comparing the results from modal analyses, and static and dynamic time-history analyses of the refined finite element model. Then, the proposed simplified model is used to determine the plastic energy dissipation of different components and the distribution of the total plastic energy dissipation over the height of the Shanghai Tower under different seismic intensities. The analysis indicates that the total plastic energy is mainly concentrated in the upper four Zones of the building and that the outrigger is the major plastic energy dissipation component in the Shanghai Tower.

Spectral Characteristics and Correlation of Dynamic Wind Loads of a Typical Super-Tall Building

This paper present some selected results of wind tunnel tests carried out on a typical super-tall building The variations of wind loads in the three orthogonal directions with wind attack direction were evaluated. The cross-correlations among various wind loading components were presented and discussed in detail. Furthermore, the across-wind spectral characteristics were studied and an empirical formula for estimation of the across-wind overturning moment spectrum for the super-tall building is presented. The output of this study is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.

Low Carbon Based Structural Design Method in Super Tall Buildings

Many super tall buildings are built up in China in recent years. The concept of low carbon based design has aroused much focus nowadays. There are few researches that combine structural design of super tall buildings with life cycle based low carbon design. Due to its huge quantity material and energy assumption, the super tall buildings exert great impact on the environment. In this study, an innovative new life cycle model is proposed for assess and optimize the life cycle environmental cost of super tall buildings, in which the space distribution of the building materials is considered besides the time dimension. A benchmark super tall building is established in this study to illustrate the application of the proposed new life cycle model. According to the case study results, a conclusion is drawn that a remarkable difference would be made in carbon emissions if low carbon based structural design method could be applied.

Field Measurement of Wind Characteristics of Typhoon Muifa on the Shanghai World Financial Center

Field measurement is considered to be the most reliable method to obtain wind characteristics of typhoon, and it is of essential value of further understanding of wind-resistant design of super tall buildings. In this paper, the wind data were recorded atop the Shanghai World Financial Center (SWFC) with a height of 494 m during the whole course of Typhoon Muifa on August 6–8 in 2011. Detailed analysis of the field data is conducted to investigate the characteristics of the typhoon-generated wind including the mean wind speed and direction, turbulence intensities, gust factors, peak factors, turbulence integral length scales, and spectra of fluctuating wind speed. A comparative study between the measured wind characteristics and those previously obtained in the literature is also carried out. It is found that the average values of turbulence intensities, gust factors, and turbulence integral length scales under the condition of Typhoon Muifa are higher than those under monsoon condition atop the SWFC, and Von Karman spectra are suitable to describe of the turbulent kinetic energy distribution at Lujiazui of the Pudong district in Shanghai.

Full-scale measurements of wind effects on Guangzhou West Tower

Field measurements of wind characteristics and wind effects on Guangzhou West Tower (GZWT) were conducted when Typhoon Megi affected this super tall building on October 22, 2010. Based on the measured wind data such as wind speed and wind direction, statistical analysis of wind characteristics including turbulence intensity, gust factor, power spectral density of wind speed at about 450m height in urban area was first conducted. The simultaneously measured wind-induced acceleration was adopted to evaluate the dynamic characteristic and wind effect on this super tall building. The damping ratio with amplitude-dependent behavior was found by the random decrement method, and the serviceability performance level for different return period was estimated for this tall building. The wind-induced pressure on the building surface atop the building was investigated to evaluate the characteristic of the measured local wind pressure. Finally, the measured wind-induced acceleration and wind pressure were further compared with those obtained from the wind tunnel test to evaluate the accuracy of the model test results. The research output is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.

Estimation of damping ratio of TV towers based on ambient vibration monitoring

SUMMARYDamping ratio is an important component in the dynamic analysis and plays a key role in design of supertall buildings. It is necessary to have reliable field measurement records for estimation of structural dynamic characteristics. The main objective of this paper is to estimate eigen mode damping ratio of TV towers as a kind of supertall buildings with the height of more than 250 m. In this regard, field measurements were performed on Milad TV tower, located in Tehran, which has a height of 435 m by ambient vibration monitoring. Damping ratio of this tower is determined using random decrement technique and compared with available data of a few other TV towers.For proposing eigen mode damping ratio of TV towers, it is shown that Rayleigh damping coefficients could not be calibrated properly for tall slender TV towers. A damping estimation chart of TV tower that is a function of natural frequency and structural aspect ratio is proposed, and the chart validity has been checked with field measurement results of other TV towers. The chart shows that structural damping for wind analysis proposed in design codes and standards is overestimated for tall slender TV towers. Copyright © 2011 John Wiley & Sons, Ltd.

An important aspect of structural design of super-tall buildings and structures: Across-wind loads and effects

An important aspect of structural design of super-tall buildings and structures: Across-wind loads and effects

Across-wind loads and effects of super-tall buildings and structures

Across-wind loads and effects have become increasingly important factors in the structural design of super-tall buildings and structures with increasing height. Across-wind loads and effects of tall buildings and structures are believed to be excited by inflow turbulence, wake, and inflow-structure interaction, which are very complicated. Although researchers have been focusing on the problem for over 30 years, the database of across-wind loads and effects and the computation methods of equivalent static wind loads have not yet been developed, most countries having no related rules in the load codes. Research results on the across-wind effects of tall buildings and structures mainly involve the determination of across-wind aerodynamic forces and across-wind aerodynamic damping, development of their databases, theoretical methods of equivalent static wind loads, and so on. In this paper we first review the current research on across-wind loads and effects of super-tall buildings and structures both at home and abroad. Then we present the results of our study. Finally, we illustrate a case study in which our research results are applied to a typical super-tall structure.

Wind effects on the world's tallest reinforced concrete building

Field measurements of wind effects on the world's tallest reinforced concrete building (CITIC Plaza, 391 m high) located in Guangzhou were made during Typhoon Damrey in 2005. The field-measured data such as wind speed, wind direction and acceleration responses were simultaneously and continuously measured from the super-tall building during the typhoon. Detailed analysis of the field data was conducted to investigate the wind characteristics and wind-induced vibration of the high-rise structure. Based on the measured acceleration data, amplitude-dependent damping ratios of the building were estimated by the random decrement method. Dynamic characteristics obtained from the field measurements were compared with those calculated from the finite-element model of the structure. The serviceability of the tall building was then analysed based on the field measured results and design codes. Finally, a time–frequency analysis was carried out by the Hilbert–Huang technique to investigate the non-stationary features of the measured wind speed and acceleration response signals. The research output is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.

Seismic analysis of the world’s tallest building

Taipei 101 (officially known as the Taipei Financial Center) with 101 stories and 508 m height, located in Taipei where earthquakes and strong typhoons are common occurrences, is currently the tallest building in the world. The great height of the building, the special geographic and environmental conditions, not surprisingly, presented one of the greatest challenges for structural engineers. In particular, its dynamic performance under earthquake or wind actions requires intensive research. The structure of the building is a mega-frame system composed of concrete filled steel tube (CFT) columns, steel brace core and belt trusses which are combined to resist vertical and lateral loads. In this study, a shaking table test was conducted to determine the constitutive relationships and finite element types for the CFT columns and steel members for establishing the finite element (FE) model of the tall building. Then, the seismic responses of the super-tall building were numerically investigated. An earthquake spectrum generated for Taipei Basin was adopted to calculate the lateral displacements and distributions of interior column forces. Furthermore, time-history analyses of elastic and inelastic seismic response were carried out using scaled accelerograms representing earthquake events with return periods of 50-year, 100-year, and 950-year, respectively. The computational results indicate that the super-tall building with the mega-frame system possesses substantial reserve strength, and the high-rise structure would satisfy the design requirements under severe seismic events. The output of this study is expected to be of considerable interest and practical use to professionals and researchers involved in the design of super-tall buildings.