Super-tall Buildings Research Articles

Aerodynamic study of the characteristics of the nest one skyscraper under wind load

To improve the safety and ease of use of super-tall buildings in strong winds, aerodynamic optimization of building shapes is considered the most effective approach. Aerodynamic optimization aims to solve a problem at its source, as opposed to structural optimization, which aims to improve the wind resistance of a structure. With the advancement of technology, buildings with complex plan shapes such as square and round, round and hexagonal, square and octagonal, etc. have been considered by many architects keeping in mind the aesthetics of the building. The wind flow around a high-rise building with complex plan shapes having different height ratios is different from what we get when analyzing a conventional shape. Since data on such buildings is not available, the need for wind tunnel or CFD testing becomes important to analyze the effects of wind on such buildings. CFD (computational fluid dynamics) for determining wind response is becoming extremely popular.

Monitoring of Wind Effects on a Super-Tall Building under a Typhoon

Field measurements are critical to further understand the structural behavior of super-tall buildings under strong wind actions. This paper presents field measurements that reflect the wind characteristics and wind effects on Leatop Plaza under Typhoon Vicente. Wind field characteristics, including the turbulence intensity, gust factor, and power spectral density of wind speed in an urban area, were obtained on the basis of a statistical analysis of measured wind data. Subsequently, measured wind-induced accelerations were used to evaluate the dynamic characteristics of the building and the effects of wind on it. On the basis of the first several modes, the modal properties, i.e., the natural frequency and damping ratio, were identified via the fast Bayesian fast Fourier transform method and compared with those identified using the stochastic subspace method. The discrepancy between the identified results and finite element model predictions is presented and discussed. Finally, the variation in the modal parameters with respect to time and the vibration amplitude was analyzed while considering the associated posterior uncertainty.

Wind Tunnel Investigation of Twisted Wind Effect on a Typical Super-Tall Building

This paper investigates the twisted wind effect on a typical super-tall building (500-m-tall square prism) by conducting pressure model wind tunnel tests. Two twisted wind fields (TWFs) with maximum yaw angles of approximately 30° and 20°, respectively, near the ground level were generated in the wind tunnel using a guide vane system, and the test results of wind pressure and wind load in TWFs were compared with those obtained in conventional wind fields (CWFs) with constant wind direction along the vertical axis. In particular, the distribution of extreme cladding pressure as well as the correlation and coherence of local wind loads are discussed in detail. It was observed that the mechanism of the structural dynamic responses, such as the vortex shedding, is greatly affected by TWFs. Both the distributions of mean and extreme cladding pressures in TWFs significantly differ from those in CWFs, especially on the windward and side facades. However, in terms of the amplitudes, the extreme wind pressure and the maximum wind load in TWFs do not noticeably exceed those in CWFs. This study aims to provide useful information for the wind-resistant design of future tall buildings.

Numerical study on structural performance of corrugated steel plate shear wall with different yield points steel

SummaryAs a new type of lateral load‐resisting system in SPSW systems, corrugated SPSWs (CSPSWs) have been gradually researched and applied. Corrugated plates offer various advantages over flat plates including higher energy dissipation capacity, ductility, out‐of‐plane stiffness, and improved buckling stability. For seismic control and isolation techniques, low yield point (LYP) steels (LY100, LY160, and LY225) are the reliable and ideal energy‐dissipating materials. The low yield point CSPSWs combine high energy‐consuming materials with high‐performance structures to provide a better solution for ductile and seismic resistance of high‐rise and super tall buildings. Currently, there are no design codes addressing the seismic performance of LYP corrugated steel plate shear walls (CSPSWs). This study investigates cyclic behavior and energy dissipation performance of corrugated steel plate yield point (100, 160, 225, 235, and 345 MPa) of different thickness CSPSWs and determine the plate yield point that provides the optimum performance. Results and findings of this study reveal that compared with the ordinary yield strength corrugated steel plates, the low yield point CSPSWs have a larger safety factor of lateral bearing capacity, a fuller hysteresis curve, a strong energy dissipation coefficient, a larger ductility coefficient and a smaller fluctuation range of strength degradation coefficient, and better strength stability. The initial equivalent stiffness of CSPSWs with different yield strengths is the same.

Effects of Reynolds number on wind effects toward a super-tall building with curved cross-section

Wind resistance is of great importance for the safety and applicability of high-rise buildings, and wind tunnel tests are generally exploited to facilitate associated wind-resistant design. However, owing to the adoption of downscaled models, Reynolds-number (Re) effects on wind tunnel testing results may not be neglected especially for structures with circular or quasi-circular sections. Although great efforts have been made to explore the Re-effects, the range of Re concerned in most studies is too limited to cover that associated with the reality. This article investigates the Re-effects on various wind effects toward a super-tall building which is featured by a spatially varying curved cross-section, based on a comprehensive usage of wind tunnel test and field measurement. The dependence of Strouhal number, pressure, layer force, structural response and equivalent static wind load upon Re from 2.5 × 104 to 3.8 × 107 is analyzed and compared with their counterparts for triangle sections and circular cylinders. Results suggest typical wind effects of the building differ distinctly from those for a circular cylinder. Both the global geometric features of the cross section and its local details (in particular the blunt leading edges) may play a significant role in forming the flow structures around the building and therefore in resulting in corresponding wind effects. Basically, at portions where the cross section varies insignificantly with height, results are much similar to those for a triangle cross-section and are less sensitive to Re; while at portions where the cross section varies significantly with height, some results become dependent greatly upon Re. Overall, the structural responses of this building first increase and then tend to level off with the increase of Re, and wind tunnel testing results basically agree with field measurements when Re exceeds about 1.3 × 105.

Investigation of long-term modal properties of a supertall building under environmental and operational variations

The information on long-term modal properties of civil structures under environmental and operational variations is generally required in structural health monitoring and vibration control. In operational modal analysis (OMA), damping estimates usually present larger fluctuations and uncertainties than natural frequency and mode shape estimates, which affects the precise determination of the long-term damping characteristics of civil structures. To this end, a combined OMA scheme is adopted in this paper based on the variational mode extraction technique and covariance-driven stochastic subspace identification algorithm to reduce errors in modal identification, especially for damping estimates. Through numerical simulation study of a three-story frame structure, the effectiveness and accuracy of the combined scheme for modal estimations are validated. Moreover, the combined approach is further utilized to evaluate the long-term modal properties of a 600 m high skyscraper under environmental and operational variations from the measured response records of 183 days. Based on the reliable modal estimates by the combined method, the effects of environmental factors (air temperature and relative humidity), wind conditions, and building response amplitudes on the long-term modal properties and their statistical characteristics are investigated in detail. This paper aims to provide an effective tool for analyzing the long-term modal properties of civil structures and further reveal the time evolution of the dynamical characteristics of supertall buildings under environmental and operation variations. • Present a combined scheme based on variational mode extraction technique and covariance-driven stochastic subspace identification algorithm to reduce errors in structural modal estimates. • Suggest an empirical formula for determining minimum length of responses required for accurate modal estimates. • Validate effectiveness and accuracy of the combined scheme via numerical simulation study. • Investigate long-term evolution of dynamical characteristics of a 600 m high skyscraper under environmental and operational variations.

Investigation on modal coupling–aeroelastic effect of a super tall building by MDOF aeroelastic model test

The prototype buildings in existing wind tunnel tests on the aeroelastic effect of super tall building are mostly hypothetical and not consider the modal coupling. In this paper, a multi-degree-of-freedom aeroelastic model was designed and wind tunnel tests were performed to research the modal coupling–aeroelastic effect of a super tall building, which exhibited significant aeroelastic effects and modal coupling during typhoon. The characteristics of wind-induced response of the model during different wind speeds were discussed. Complex mode decoupling technique and Bayesian approach were used to identify and analyze the variation of the first two modal parameters of the model with reduced wind velocity. Finally, wind tunnel test results were compared with field measurements. Results show that compared with the narrow-side windward, the cross-wind vortex-induced resonance of the model is more obvious when the model is wide-side windward. The along-wind modal frequency and damping ratio show similar variation with reduced wind velocity as cross-wind modal frequency and damping ratio. Moreover, the along-wind mode shape approaches the cross-wind mode shape at the reduced wind velocity of resonance. The peak accelerations predicted from the aeroelastic model test are in good agreement with the field measurements.

Recovery of missing field measured wind pressures on a supertall building based on correlation analysis and machine learning

In long-term field measurements and structural health monitoring (SHM), data loss sometimes occurs due to interruption of power supply, sensor failure, and disruption of data transmission, which inevitably affects subsequent data analysis and structural condition assessment. To address this issue, this paper proposes a novel data recovery method based on correlation analysis and machine learning (ML) for recovery of missing wind pressures on cladding of high-rise buildings in field measurements and SHM. The method first utilizes correlation analysis to select appropriate inputs of the ML model, and subsequently to recover the missing wind pressures using the ML model with the selected appropriate inputs. In this study, four ML models (i.e., data recovery models), including deep neural network (DNN), particle swarm optimization-DNN (PSO-DNN), extreme learning machine (ELM), and support vector regression (SVR), are developed based on the proposed data recovery method. The time series of wind pressures with non-Gaussian features, which were collected by a multi-point synchronous monitoring system on a 600-m-high skyscraper during Super Typhoon Mangkhut, are employed to validate the performance of the developed data recovery models. The results show that all the four ML models perform satisfactorily in the recovery of the missing time series of wind pressures, among which the PSO-DNN model performs best and has good recovery accuracy for data loss that occurs in different areas of building cladding. This demonstrates that the proposed data recovery method based on correlation analysis and machine learning is a reliable and effective tool to recover the missing time series of wind pressures on high-rise buildings under severe wind conditions. Notably, this is the first attempt based on field measurements to recover the missing time series of wind pressures with non-Gaussian characteristics on a skyscraper during an extreme typhoon event, which aims to provide a useful means for the recovery of missing monitoring data in field measurements and SHM.

Aerodynamic Shape Optimization of a Square Cylinder with Multi-Parameter Corner Recession Modifications

Corner modifications can reduce wind loads acting on supertall buildings and modify the corresponding flow structures. The present study investigated the aerodynamic shape optimization of the corner recession square cylinders with multiple geometric parameters in a large design space via the GA-GRNN surrogate model updating-based multi-objective optimization framework. Six typical optimal aerodynamic shape sections M1~M6 were selected from the Pareto optimal front, and the effects of multiple geometric parameters of these sections on the aerodynamic performance and flow field were analyzed. The results showed that the present multi-objective optimization framework can significantly reduce the computational load and time cost, and significantly improve the optimization efficiency in solving complex engineering problems. The optimal corner recession sections can obviously reduce the mean drag coefficient CD and root mean square lift coefficient CσL while significantly increasing the Strouhal number St of the square cylinder, and it is concluded that the aerodynamic shape optimization can significantly improve the aerodynamic performance of square-sectional supertall buildings. When compared with the benchmark section, the CD and CσL of the optimal section M1 can be reduced up to 45.7% and 84.5%, respectively. Based on the analysis of the flow structures around the optimal sections, the flow mechanism can be attributed to the fact that the corner recession modifications postpone the flow separation, and deflect the separated shear layer towards the side surfaces and suppress the development of vortex shedding in the wake, which leads to significant elongation of the wake length and reduction of the width of the recirculation region. The proposed multi-objective optimization framework in this study can provide an important reference for the aerodynamic shape optimization of building structures and relevant studies.

Investigation of modal parameters of a 600-m-tall skyscraper based on two-year-long structural health monitoring data and five typhoons measurements

On the basis of two-year-long structural health monitoring data, this paper investigates the structural dynamic properties of a 600-m-high supertall building installed with an active tuned mass damper (ATMD) system. The long-term modal parameters such as natural frequencies and damping ratios of the monitored skyscraper are first determined by the stochastic subspace identification approach, and the results generally agree well with those obtained by the finite element method and forced vibration tests. The statistical analysis of the modal parameters indicates that the natural frequencies follow the normal distribution, while the damping ratios fit well with the Gumbel distribution. In addition, the two-year-long variations of the modal parameters with ambient environmental factors are investigated and it is found that both the ambient temperature and humidity have limited effects on the modal parameters of the skyscraper. Moreover, the impacts of the ATMD system on the modal parameters are explored based on the field measurements during five typhoons. The analyzed results demonstrate that the active damper system had significant effects on the modal parameters of the fundamental sway modes, while it had marginal influences on these of higher modes. This study aims to enhance the understanding of structural dynamic properties of supertall buildings and provide useful information for their wind-resistant design.

Modal identification of high-rise buildings by combined scheme of improved empirical wavelet transform and Hilbert transform techniques

Recently, the empirical wavelet transform technique has attracted much attention due to its advantage of dealing with non-stationary and nonlinear signals. For empirical wavelet transform-based methods, their performance is heavily dependent on the accuracy of Fourier spectral segmentation. Structural response signals of high-rise buildings under ambient excitations often include high-level noises, which may lead to inaccurate spectral estimation, thereby introducing errors in modal decomposition. To this end, an improved empirical wavelet transform method is presented in this paper to analyze the structural response signals with high-level noises, which employs the projection information of Fourier spectra to improve spectral representation. Then, the improved empirical wavelet transform method is combined with the natural excitation technique and Hilbert transform for identifying modal properties of super-tall buildings under ambient excitations. Through a numerical simulation study, the validity and accuracy of the combined scheme are verified even when structural response signals were embedded with high levels of noise. Furthermore, the proposed method is adopted for modal identification of a 600 m supertall building for evaluating its applicability in field measurements. It is demonstrated that the combined scheme can effectively and accurately evaluate the modal properties of the skyscraper under ambient vibrations with low amplitudes.

Investigation of structural responses and dynamic characteristics of a supertall building during Typhoon Kompasu

In this paper, comprehensive field measurements were conducted on a 600-m-high skyscraper in Shenzhen during Typhoon Kompasu based on structural health monitoring (SHM) system and a remotely non-contact interferometric radar system called IBIS-FS. The SHM system recorded wind field and structural responses, including accelerations at 10 building heights by accelerometers and horizontal displacements atop the building by global positioning system (GPS). Meanwhile, the IBIS-FS simultaneously measured the horizontal displacements of the building at multiple heights. This is the first time that the interferometric radar system, i.e., IBIS-FS, is applied to the displacement monitoring of a supertall building under typhoon conditions. The effectiveness of the IBIS-FS is verified through comparing the building responses measured by the IBIS-FS with those measured by the SHM system. Then, based on the field-measured responses, the mean, background, and resonant responses of the monitored supertall building are extracted and analyzed; and the amplitude dependencies and time-varying characteristics of the structural modal parameters (i.e., natural frequencies and damping ratios) are presented and discussed. The results show that the IBIS-FS can provide convenient and accurate displacement measurements of the skyscraper under severe weather conditions. This paper aims to provide useful information for SHM and wind-resistant design of supertall buildings in tropical cyclone-prone regions.

Study on Wind Load Characteristics and Wind-Induced Response of Supertall Buildings with Single-Sided Large-Span Straight Platforms

The presence of large-span straight platforms can complicate the airflow around buildings and alter surface wind pressure, gas bypass and wind response in supertall buildings. The article uses the Reynolds-averaged Navier–Stokes (RANS) method in Computational Fluid Dynamics (CFD) to investigate the differences in surface mean wind pressure, gas bypass, wind coefficients, displacement and acceleration responses between the models with and without platforms, and the wind load on the platforms themselves at different wind directions. The results show that: the presence of platforms generally reduces the maximum negative pressure coefficient on the building surface, reaching a maximum reduction of 31.56% at 30°, and causes a small increase in the maximum positive pressure coefficient, reaching a maximum increase of 5.30% at 0°. The mean wind pressure on the lower surface of the platform is greater than the upper surface. The target building has a lower frequency of vortex shedding than the reference model, with a maximum reduction of 5.68%. The presence of platforms increases the vertex displacement of the building by up to 22.85% and decreases the vertex acceleration by up to 9.14%. These results can be used as references for the ventilation, comfort and safety assessment of similar supertall buildings.

Interrelations of slenderness ratio and main design criteria in supertall buildings

PurposeTo date, there are no studies in the literature that provide a comprehensive understanding of the interrelationships between the slenderness ratio and the main design criteria in supertall towers (=300 m). In this paper, this important issue was explored using detailed data collected from 75 cases.Design/methodology/approachThis paper was carried out with a comprehensive literature review including the database of the Council on Tall Buildings and Urban Habitat(CTBUH) (CTBUH, 2022), peer-reviewed journals, MSc theses and PhD dissertations, conference proceedings, fact sheets, architectural and structural magazines and other Internet sources. In this study, the case study method was also used to gather and consolidate information about supertall towers to analyze the interrelationships. Cases were 75 supertall buildings in various countries [44 from Asia (37 from China), 16 from the Middle East (6 from Dubai, the United Arab Emirates), 11 from the United States of America and 3 from Russia, 1 from the UK].FindingsThe paper's findings highlighted as follows: (1) for buildings in the height range of 300–399 m, the slenderness ratio was usually between 7 and 7.9 and megatall towers were frequently built at a slenderness ratio of 10–15; (2) the median slenderness ratio of buildings in the 400–599 m height ranges was around 8.6; (3) a trend towards supertall slender buildings (=8) was observed in Asia, the Middle East and North America; (4) residential, office and mixed-use towers had a median slenderness ratio of over 7.5; (5) all building forms were utilized in the construction of slender towers (>8); (6) the medium slenderness ratio was around 8 for supertall buildings constructed with outriggered frame and tube systems; (7) especially concrete towers reached values pushing the limits of slenderness (>10) and (8) since the number of some supertall building groups (e.g. steel towers) was not sufficient, establishing a scientific relationship between aspect ratio and related design criteria was not possible.Originality/valueTo date, there are no studies in the literature that provide a comprehensive understanding of the interrelationships between the slenderness ratio and the main design criteria in supertall towers (=300 m). This important issue was explored using detailed data collected from 75 cases.

Investigation of a self-centering frictional energy dissipation outrigger equipped to supertall buildings

Outrigger is a typical lateral-force resisting component for supertall buildings, and high-performance outriggers with excellent energy dissipation have been widely studied to enhance the seismic resilience of supertall buildings. However, the residual displacement of the outrigger still limits the rapid repair of the structure after earthquakes. This paper puts forward a self-centering frictional energy dissipation outrigger (SCFO) that consists of self-centering frictional devices (SFDs) and a steel truss in series. A scaled SFD is designed and tested under cyclic loading, and the refined finite element models of the SCFO are established to study their hysteretic performance in detail. Further parametric analysis is conducted to discuss the influence of key parameters, such as strength ratio and stiffness ratio, on the hysteresis characteristics of the SCFO. The results indicate that when the strength and stiffness ratios do not exceed 0.75 and 0.054, respectively, the proposed SCFO has excellent self-centering capacity and stable energy dissipation capacity. The functionality can be restored without repair or requiring only a simple repair after earthquakes.

Risk-averse design of tall buildings for uncertain wind conditions

Reducing the intensity of wind excitation via aerodynamic shape modification is a major strategy to mitigate the reaction forces on supertall buildings, reduce construction and maintenance costs, and improve the comfort of future occupants. To this end, computational fluid dynamics (CFD) combined with state-of-the-art stochastic optimization algorithms is more promising than the trial and error approach adopted by the industry. The present study proposes and investigates a novel approach to risk-averse shape optimization of tall building structures that incorporates site-specific uncertainties in the wind velocity, terrain conditions, and wind flow direction. A body-fitted finite element approximation is used for the CFD with different wind directions incorporated by re-meshing the fluid domain. The bending moment at the base of the building is minimized, resulting in a building with reduced cost, material, and hence, a reduced carbon footprint. Both risk-neutral (mean value) and risk-averse optimization of the twist and tapering of a representative building are presented under uncertain inflow wind conditions that have been calibrated to fit freely-available site-specific data from Basel, Switzerland. The risk-averse strategy uses the conditional value-at-risk to optimize for the low-probability high-consequence events appearing in the worst 10% of loading conditions. Adaptive sampling is used to accelerate the gradient-based stochastic optimization pipeline. The adaptive method is easy to implement and particularly helpful for compute-intensive simulations because the number of gradient samples grows only as the optimal design algorithm converges. The performance of the final risk-averse building geometry is exceptionally favorable when compared to the risk-neutral optimized geometry, thus, demonstrating the effectiveness of the risk-averse design approach in computational wind engineering.

Shaking table test and seismic behavior of Ningbo Hengda Tower

SummaryA super tall building named Ningbo Hengda Tower is located in Ningbo City, China. It has 91 stories with a total height of 450 m. The structure system of the building consists of three parts, that is, the reinforced concrete core, the outer frame system, and the outrigger trusses connecting the core wall and outer frame. The unique outer frame system is spindle shaped with oblique columns. The outrigger trusses are located at three different levels above the ground, thus strengthening the building and creating irregularities in the stiffness of the structure along the building height. Great challenges are existed in seismic design and analysis of the building. Shaking table test was carried out for a 1/40 scaled model of the building under a series of different base excitations with increasing amplitudes. The dynamic properties, seismic responses, and failure mechanism of the structure are investigated. Test results show that the structure behaved well under designed level earthquakes. The weak points of the structure are identified based on visible damage of the tested model, and some suggestions are made for the improvement of the seismic behavior of the building. It is suggested that measures be taken to improve the ductility of the building from floor 71 to floor 79 and the adjacent floors.

Seismic Performance of Super High-Rise Building Structure with Dual Lines of Defense Based on Response Surface Optimization Algorithm

In order to improve the safety performance of supertall buildings under earthquake, a seismic performance analysis method of double lines of supertall buildings based on a response surface optimization algorithm is proposed. Firstly, the structural performance indexes of super high-rise buildings are selected, and on this basis, the material constitutive model is constructed by the structural elastic-plastic analysis method to complete the seismic design of the first line of defense. Then, the response surface method is used to optimize the material constitutive model and complete the seismic design of the second line. Finally, the anticollapse limit state analysis method is used to determine the seismic performance of the double line of super high-rise building structures. The experimental results show that the proposed analysis method has high seismic performance, and the axial compression ratio of wall and column is always stable, in which the column is always at about 0.5 and the wall is always at about 0.26, which lays a foundation for the safety performance of super high-rise building structures under earthquake.

Tuned tandem mass dampers-inerters for suppressing vortex-induced vibration of super-tall buildings

Modern super-tall buildings with rectangular floor shapes are vulnerable to significant vibrations due to the vortex shedding effect formed around structural edges. Tuned tandem mass dampers-inerters (TTMDI) is extended in this study to suppress vortex-induced responses of super tall buildings for occupant comforts. The optimal TTMDI tuning problem for a 400 m super tall building exposed to crosswind loads is solved through frequency-domain analysis. Meanwhile, the control performance of TTMDI is explored and contrasted with that of the tuned mass damper (TMD), tuned tandem mass dampers (TTMD) and tuned mass damper‐inerter (TMDI) from various perspectives. A crosswind-resistant design framework of the TTMDI equipped super-tall building system is then devised to meet comfort requirements. Finally, results are further assessed in the time -domain using a virtual real time hybrid simulation (VRTHS) system based on the proposed hybrid model predictive controller. It is found that there are several optimal inertance coefficient redistribution points (i.e. R points) in the design process and the R points have a great impact on the optimal internal structure of TTMDI. Results clearly demonstrate that TTMDI has better effectiveness and robustness than TMD, TTMD, and TMDI. Moreover, the total demand for total damping coefficients of TTMDI is significantly smaller than TMDI after the R points, indicating that it is easier to implement in engineering practices.

Use of aerodynamically favorable tapered form in contemporary supertall buildings

Today, supertall buildings can be constructed in unusual forms as a pragmatic reflection of advances in construction techniques and engineering technologies, together with advanced computational design tools for architectural design. As with many other buildings, architectural and practical principles play a crucial role in the form of a supertall building, where aerodynamic behavior shaped by wind-induced excitations also becomes a critical design input. Various methods are used to meet the functional needs of these towers and reduce excitations, including aerodynamic modification methods directly related to the building form. Tapered forms are one of the most frequently used and most effective methods in today's skyscrapers, which significantly affect architectural design. To date, no study has been conducted in the literature that provides an understanding of the interrelationships between tapered building forms and main planning criteria, considering the aerodynamic design concerns of the tapering effect in supertall buildings (≥300 m). This important issue is explored in this article with data gathered from 41 supertall case studies, considering location, function, structural system, and structural material as well as the aerodynamic taper effect. The main findings of the study highlighted the following: (1) Asia was where tapered towers were most favored, with a wider margin in all regions; (2) mixed-use was the most preferred function in selected supertall buildings with tapered form; (3) outriggered frame systems were mainly used; (4) tapered supertall cases were mostly built in composite; (5) the sample group included 17 cases that used the tapering effect with aerodynamic design concerns, some of which were accompanied by corner modifications. It is believed that this study will be a basic guide for design and construction professionals including architectural and structural designers, and contractors.