Estimation Formula of Modal Frequency of High-Rise Buildings under Different Wind Speeds during Typhoons

Jiaxing Hu,Zhengnong Li,Zhefei Zhao

doi:10.3390/app12010047

Jiaxing Hu, Zhengnong Li + Show 1 more

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https://doi.org/10.3390/app12010047

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Abstract

On 18 October 2016, the wind-induced effects of a high-rise building with square section was measured by the monitoring system in Haikou of China during Typhoon Sarika. The wind characteristics atop the building and the time-history responses of the translational and rotational accelerations on different floors were measured by the monitoring system; the first three modal parameters were identified according to the measured acceleration. The results show that the combinations of the cross spectral density function, phase spectrum, and coherence function can clearly judge the phase of the measured floors in the frequency resonance area as well as its modal frequencies at the first three orders. The modal frequencies at the first three orders decrease linearly with the growth of mean wind speed within the range of 0~20m/s. The estimation formula of the modal frequencies of high-rise buildings considering the influences of different wind speeds is put forward, which is expected to fill the gap in the existing specification for the quantitative analysis of the influences of wind-loads on the fundamental frequencies of high-rise buildings.

Highlights

According to the measured vibration signal data, the modal parameter identification of high-rise buildings is the processing method used to estimate the natural frequency, damping ratio, and vibration mode of the structure
This paper took the influences of wind-induced response on fundamental frequencies into consideration during typhoons, and the es
(2) The auto-power spectral density function, cross-spectral density function, phase spectrum, and coherence function can be applied to identify the first three-order modal frequencies of the building and to judge where different floors locate in the vibration shapes of resonance region

Summary

Introduction

According to the measured vibration signal data, the modal parameter identification of high-rise buildings is the processing method used to estimate the natural frequency, damping ratio, and vibration mode of the structure. With the characteristics of light weight, high flexibility, and low damping, modern high-rise buildings are more sensitive to wind-induced vibration, the reliable estimations of modal parameters are vital to design and evaluate the safety and applicability of structures. A three-dimensional accelerometer is widely used in the modal identifications of high-rise buildings, by which the measured acceleration is often regarded as the translation along the east–west, south– north, and vertical directions. A large number of studies have confirmed that the rotational component contributes a lot to the earthquake and wind-induced responses of structures. Many studies showed that the torsional vibration components of high-rise buildings contribute a lot to the structural responses. Because of some limitations of the measuring sensors, the rotational measurements are not as widely used as the translational measurements (acceleration, speed, and displacement)

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