scholarly journals Damping and Natural Period Evaluation of Tall RC Buildings Using Full-Scale Data in Korea

2020 ◽  
Vol 10 (5) ◽  
pp. 1568
Author(s):  
Taehyu Ha ◽  
Seung-Hoon Shin ◽  
Hongjin Kim
Keyword(s):  
Damping Ratio ◽  
Tall Buildings ◽  
Vibration Measurement ◽  
Ambient Vibration ◽  
Induced Response ◽  
Rc Buildings ◽  
Natural Period ◽  
Rc Structures ◽  
High Rise ◽  
Induced Motion

In recent years, the main usage of reinforced concrete (RC) structures in Korea has shifted from low-rise residential and commercial buildings to high-rise buildings. Because an increasing number of high-rise RC buildings are being built, especially in coastal cities, which are periodically hit by typhoons, wind-induced motion and the corresponding serviceability issues have attracted considerable attention. Natural period and damping ratio are the most important factors for estimating the design wind load and wind-induced response in the design of tall buildings. However, the Korean Building Code (KBC 2009) does not specify empirical formulae for estimating the natural period and damping ratio for wind design, unlike seismic design. In this study, the damping ratio and natural period of existing concrete buildings in Korea are measured and compared to those obtained using the formulae provided in various codes and research works. Furthermore, design formulae for estimating natural frequency and damping ratio for wind design are proposed based on the measured data. For this purpose, ambient vibration measurement is performed for 58 RC buildings with heights of 24.2–305 m.

scholarly journals Wind-Induced Response Control of High-Rise Buildings Using Inerter-Based Vibration Absorbers

2019 ◽  
Vol 9 (23) ◽  
pp. 5045 ◽  
Author(s):  
Qinhua Wang ◽  
Haoshuai Qiao ◽  
Dario De Domenico ◽  
Zhiwen Zhu ◽  
Zhuangning Xie
Keyword(s):  
Damping Ratio ◽  
Element Model ◽  
Tuned Mass Damper ◽  
Induced Response ◽  
Vibration Absorbers ◽  
Acceleration Response ◽  
Vibration Mitigation ◽  
High Rise ◽  
Mass Damper ◽  
Good Trade

The beneficial mass-amplification effect induced by the inerter can be conveniently used in enhanced variants of the traditional Tuned Mass Damper (TMD), namely the Tuned Mass-Damper-Inerter (TMDI) and its special case of Tuned Inerter Damper (TID). In this paper, these inerter-based vibration absorbers are studied for mitigating the wind-induced response of high-rise buildings, with particular emphasis on a 340 m tall building analyzed as case study. To adopt a realistic wind-excitation model, the analysis is based on aerodynamic forces computed through experimental wind tunnel tests for a scaled prototype of the benchmark building, which accounts for the actual cross-section of the structure and the existing surrounding conditions. Mass and stiffness parameters are extracted from the finite element model of the primary structure. Performance-based optimization of the TMDI and the TID is carried out to find a good trade-off between displacement- and acceleration-response mitigation, with the installation floor being an explicit design variable in addition to frequency and damping ratio. The results corresponding to 24 different wind directions indicate that the best vibration mitigation is achieved with a lower installation floor of the TMDI/TID scheme than the topmost floor. The effects of different parameters of TMD, TMDI and TID on wind-induced displacement and acceleration responses and on the equivalent static wind loads (ESWLs) are comparatively evaluated. It is shown that the optimally designed TMDI/TID can achieve better wind-induced vibration mitigation than the TMD while allocating lower or null attached mass, especially in terms of acceleration response.

Dynamic Response of Tall Buildings on Sedimentary Basin to Long-Period Seismic Ground Motion

2016 ◽  
Vol 11 (5) ◽  
pp. 857-869 ◽  
Author(s):  
Nobuo Fukuwa ◽  
◽  
Takashi Hirai ◽  
Jun Tobita ◽  
Kazumi Kurata ◽  
...  
Keyword(s):  
Ground Motion ◽  
Sedimentary Basin ◽  
Tall Buildings ◽  
Ambient Vibration ◽  
Reciprocal Theorem ◽  
The 2011 Tohoku Earthquake ◽  
Natural Period ◽  
Seismic Ground Motion ◽  
Wave Amplification ◽  
Long Period

Characteristics of long-period seismic ground motion and response of tall buildings are investigated in this paper to promote earthquake proof countermeasures considering the damage caused by the 2011 Tohoku earthquake. 3D finite difference method and the reciprocal theorem are used to examine the effect of sedimentary basin structures on seismic wave amplification. Natural period and damping of tall buildings are evaluated by ambient vibration tests and earthquake response observation during construction or demolition of the buildings. The effects of dynamic soil-structure interaction on response amplification of tall buildings are confirmed applying wave propagation theory to a continuum building model. Finally, a newly built base-isolated building with an isolated rooftop laboratory is introduced for full-scale long-period shaking experiment by installing actuators and jacks. Experience of long-period shaking in the building is also available with virtual reality view of indoor damage, which is effective for promotion of seismic countermeasures such as fixing furniture and safe evacuation.

scholarly journals Identification of vibration properties of a midrise wooden building using subspace identification method

2018 ◽  
Vol 211 ◽  
pp. 14007
Author(s):  
Yuji Miyazu ◽  
Takuro Mori
Keyword(s):  
Damping Ratio ◽  
Full Scale ◽  
Seismic Load ◽  
Subspace Identification ◽  
Natural Period ◽  
High Rise ◽  
Identification Method ◽  
Amplitude Dependency ◽  
Low Amplitude ◽  
Subspace Identification Method

Recent years, the mid- and high-rise wooden building using cross-laminated timber (CLT) is on the increase in the world. In the regions highly subjected to seismic events, it is important to know the basic property of the vibration of the building to design the building to be safety enough against the seismic load; however, there is enough such data of full scale wooden buildings. In this paper, the natural period, the damping ratio, and the mode shape of a full-scale five-story wooden building are evaluated using subspace identification method. The results show that the damping ratios of higher modes tend to be lower than that of the first mode, and the natural period and the damping ratio show amplitude dependency even in the range of low amplitude.

Testing in-Phase Analysis for Adjacent Transmission Towers under Ambient Vibration

2011 ◽  
Vol 105-107 ◽  
pp. 112-116
Author(s):  
Xiang Mei Yan
Keyword(s):  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Longitudinal Direction ◽  
Ambient Vibration ◽  
Induced Response ◽  
Line System ◽  
Vibration Data ◽  
Transmission Towers ◽  
Ambient Vibration Testing ◽  
Suspended Cables

Based on the random vibration and system identification theory, the ambient vibration testing of two adjacent transmission towers were carried out, dynamic characteristics of the towers were obtained from ambient vibration data. The result shown that the suspended cables not only have mass effects, but have coupled stiffness effects applied to tower on transverse direction and longitudinal direction. At the same, testing value shows that the two adjacent towers have basically the same dynamic characteristics and damping ratio of the two transmission towers less than 0.01. Owing to the influence of conductors, frequency of the insulators is different to the towers at the two directions. It is disadvantage for wind-induced response of transmission line system under ambient loads.

Damage Detection of Building Structures Using Ambient Vibration Measurement

2007 ◽  
Vol 348-349 ◽  
pp. 721-724
Author(s):  
S.H. Yoo ◽  
S.Y. Kim ◽  
S.W. Shin
Keyword(s):  
Damage Detection ◽  
Measurement Data ◽  
Tall Buildings ◽  
Steel Structures ◽  
Least Square ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Vibration Measurement ◽  
Ambient Vibration ◽  
Building Structures

System identification(SI) techniques using dynamic responses and behaviors of structural systems become an outstanding issue of researchers. However the conventional SI techniques are identified to be non-practical to the complex and tall buildings, due to limitation of the availability of an accurate data that is magnitude or location of external loads. Thus a technique to estimate structural properties of building without input measurement data and using limited response is essential in structural health monitoring. In this study, the improved least square method for damage detection is proposed and verified by shaking table tests on three-story plane frame steel structures. In results damage detection was performed in each member level.

A Family of Efficient Sloshing Liquid Dampers for Suppression of Wind-Induced Instabilities

2003 ◽  
Vol 9 (3-4) ◽  
pp. 361-386 ◽  
Author(s):  
V. J. Modi ◽  
A. Akinturk ◽  
W. Tse
Keyword(s):  
Energy Dissipation ◽  
High Efficiency ◽  
Damping Ratio ◽  
Real Life ◽  
Wind Tunnel Test ◽  
Tall Buildings ◽  
Two Phases ◽  
Liquid Dampers ◽  
Obstacle Geometry ◽  
Floating Particles

Bluff structures in the form of tall buildings, smokestacks, control towers, bridges, etc., are susceptible to vortex resonance and galloping type of instabilities. One approach to vibration control of such systems is through energy dissipation using sloshing liquid dampers. In this paper we focus on enhancing the energy dissipation efficiency of a rectangular liquid damper through the introduction of two-dimensional obstacles as well as floating particles. The investigation has two phases. To begin with, a parametric free vibration study aimed at the optimization of the obstacle geometry is undertaken to arrive at configurations promising increased damping ratio and hence higher energy dissipation. The study is complemented by an extensive wind tunnel test program, which substantiates the effectiveness of this class of damper in suppressing both vortex resonance and galloping type of instabilities. Simplicity of design, ease of implementation, minimal maintenance, reliability as well as high efficiency make such liquid dampers quite attractive for real-life applications.

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