Investigation of Wind Loading, Structural Responses and Vibration Control of a 600m Skyscraper

Abstract

High-rise buildings with increasing height have been substantially constructed in recent years due to the developments in new materials and advanced construction techniques. Meanwhile, the increasing height may lead to relatively weak structural stiffness and low damping, making these skyscrapers more sensitive to dynamic wind loads. Particularly, skyscrapers in typhoon-prone regions usually suffer from excessive wind-induced vibrations, which may cause unfavorable or even dangerous conditions to their occupants. Therefore, it is of great concern to further the understanding of the wind effects on skyscrapers, so as to provide more useful information for the wind-resistant design and vibration control of future skyscrapers.

This thesis presents a comprehensive study of the wind effects on a 600 meters high skyscraper located in a typhoon-prone region, which is an ideal test bed to conduct such a study. The research works contained in this thesis include three main parts. The first part presents the investigation of the wind loadings on the skyscraper; the next part investigates the wind-induced structural responses of the skyscraper; and the third part evaluates the vibration control of the skyscraper, including using the tuned mass damper system and the active mass damper system.

In the first part, a detailed study of wind loading on the concerned skyscraper is carried out by means of wind tunnel tests and full-scale measurements. In the wind tunnel tests, wind-induced loads and pressures on the skyscraper are measured using both high frequency force balance technique (HFFB) and synchronous multi-pressure sensing system (SMPSS), and a whole range of characteristic properties, including mean and root-mean-square (rms) force coefficients, power spectral densities, coherences, correlations and phase-plane trajectories, are estimated and discussed. In addition, full-scale measurements and wind tunnel tests are conducted respectively to examine the wind-induced pressures on all the facades of the skyscraper, and comparative analysis of the results is performed.

The second part concentrates on the evaluation of the wind-induced structural responses of the skyscraper through both wind tunnel and full-scale tests. The information regarding the structural dynamic properties (e.g. modal parameters) is essential for the accurate prediction of the structural responses. Hence, a series of full-scale measurement studies, including ambient vibration test (AVT) and forced vibration test (FVT), are performed on-site to identify the modal parameters of the concerned skyscraper. Subsequently, the identified modal parameters are used to determine the wind-induced structural responses of the skyscraper in the wind tunnel study. The displacement and acceleration responses under conditions of which with and without existing surroundings are individually investigated. Moreover, the wind-induced structural responses of the concerned building are examined as a function of incident wind direction, upstream terrain conditions and interferences from the surroundings. Likewise, full-scale measurements of the structural responses of the skyscraper are conducted during the passages of strong typhoons.

The third part of this thesis is concerned with the vibration control of the skyscraper. Given the limited space available on site, a multistage pendulum tuned mass damper (PTMD) system is recommended for the building with aims to mitigate the discomforting structural vibrations. The optimal design of the multistage PTMD system is performed by examining the mitigation efficiency of the PTMD system associated with a variety of mass ratio and damping ratio. Furthermore, to restrict the strokes of PTMD system, a mass damper with a two-section damping configuration is proposed. It is shown that the proposed multistage PTMD system with two-section-damping can function efficiently to suppress the excessive vibrations of the skyscraper and meanwhile occupies a minimal space in vertical and horizontal directions.

In addition, the research is further extended to the application of active mass damper (AMD) system. The concerned skyscraper has been equiped with an AMD system, which is the world’s largest of its kind. The effectiveness of the AMD system is assessed using numerical simulation analysis based on the wind tunnel test results. The wind-induced structural responses under the control of the AMD system are further compared with those under the control of a PTMD system to assess the performances of the active and passive control techniques. Moreover, on-site forced vibration tests are undertaken to evaluate the control effectiveness of the AMD system. It is found that the AMD system can increase the damping ratio of the fundamental swaying mode up to 12.8 times. Then, statistical analysis of the acceleration signals measured from the skyscraper with the operation of the AMD system during super Typhoon Mangkhut (September 2018) is presented. The field measurement results show that the AMD system functioned efficiently for suppression of the wind-induced vibrations of the skyscraper during the strong typhoon event.

To sum up, this thesis focuses primarily on the investigation of wind loading, structural responses and vibration control of a 600 meters high skyscraper using wind tunnel tests, field measurements and numerical simulations. The objective of this study is to enrich the knowledge and further our understanding of the wind effects on skyscrapers in typhoon-prone regions, and the outcomes are expected to provide useful information for the wind-resistant design and vibration control of future skyscrapers.

Date of Award	13 Jun 2019
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Qiusheng LI (Supervisor)