Using an ambient vibration test to identify damage in a sculpture

2021 ◽  
Author(s):  
Elsa Caetano
Keyword(s):  
Numerical Model ◽  
Natural Frequencies ◽  
Second Order ◽  
Ambient Vibration ◽  
Modal Parameters ◽  
Vibration Test ◽  
Vibration Modes ◽  
Ambient Vibration Test ◽  
Degraded Area

<p>This paper describes the studies conducted to assess damage in a sculpture. These include a numerical model and an ambient vibration test based on a dense mesh of points to identify the fundamental natural frequencies and the corresponding modal shapes. From the comparison between identified and calculated modal parameters, it was possible to identify a region of inflexion of curvatures of the second-order vibration modes at a particular location that was associated with a local fragility of the structure. A posterior removal of the cladding evidenced a highly degraded area at this location.</p>

Bayesian model updating of a 20-story office building utilizing operational modal analysis results

2019 ◽  
Vol 22 (16) ◽  
pp. 3385-3394
Author(s):  
Heung Fai Lam ◽  
Jun Hu ◽  
Mujib Olamide Adeagbo
Keyword(s):  
Bayesian Model ◽  
Structural Model ◽  
Model Updating ◽  
Dynamic Properties ◽  
Ambient Vibration ◽  
Modal Parameters ◽  
Vibration Test ◽  
Ambient Vibration Test ◽  
Building Model ◽  
Shear Building

Most existing buildings are not equipped with long-term monitoring system. For the structural model updating and damage detection of this type of structures, ambient vibration test is popular as artificial excitation is not required. This article presents in detail the full-scale ambient vibration test, operational modal analysis, and model updating of a tall building. To capture the dynamic properties of the target 20-story building with limited number of sensors, a 15-setup ambient vibration test was designed to cover at least three measurement points (each consists of a vertical and two orthogonal horizontal measured degrees of freedom) for each selected floor. The modal parameters of each setup were extracted from the measured acceleration signals using a frequency domain decomposition method and were combined to form the global mode shape through the least-squares method. Due to the regularity of the building, a simple class of shear building models was employed to capture the dynamic characteristics of the building under lateral vibration. The identified modal parameters of the building were employed for the model updating of the shear building model to identify the distribution of inter-story stiffness. Since the “amount” of the measured information is small when compared to the “amount” of required information for identifying the uncertain parameters, the model updating problem is unidentifiable. To handle this problem, the Markov chain Monte Carlo–based Bayesian model updating method is employed in this study. The identified modal parameters revealed interesting features about the dynamic properties of the building. The well-matched results between model-predicted and identified modal parameters show the validity of the shear building model in this case study. This study provides valuable experience in the area of structural model updating and structural health monitoring.

Ambient Vibration Test, Modal Identification and Structural Model Updating Following Bayesian Framework

2015 ◽  
Vol 15 (07) ◽  
pp. 1540024 ◽  
Author(s):  
J. Yang ◽  
H. F. Lam ◽  
J. Hu
Keyword(s):  
Bayesian Model ◽  
Structural Model ◽  
Model Updating ◽  
Modal Identification ◽  
Ambient Vibration ◽  
Modal Parameters ◽  
Vibration Test ◽  
Engineering Structures ◽  
Ambient Vibration Test ◽  
Vibration Data

Structural health monitoring (SHM) of civil engineering structures based on vibration data includes three main components: ambient vibration test, modal identification and model updating. This paper discussed these three components in detail and proposes a general framework of SHM for practical application. First, a fast Bayesian modal identification method based on Fast Fourier Transform (FFT) is introduced for efficiently extracting modal parameters together with the corresponding uncertainties from ambient vibration data. A recently developed Bayesian model updating method using Markov chain Monte Carlo simulation (MCMCS) is then discussed. To illustrate the performance of the proposed modal identification and model updating methods, a scale-down transmission tower is investigated. Ambient vibration test is conducted on the target structure to obtain modal parameters. By using the measured modal parameters, model updating is carried out. The MCMC-based Bayesian model updating method can efficiently evaluate the posterior marginal PDFs of the uncertain parameters without calculating high-dimension numerical integration, which provides posterior uncertainties for the target systems.

Operational Modal Analysis and Bayesian Model Updating of a Coupled Building

2018 ◽  
Vol 19 (01) ◽  
pp. 1940012
Author(s):  
Jun Hu ◽  
Jia-Hua Yang
Keyword(s):  
Bayesian Model ◽  
Main Part ◽  
Structural Model ◽  
Model Updating ◽  
Dynamic Properties ◽  
Ambient Vibration ◽  
Modal Parameters ◽  
Vibration Test ◽  
Ambient Vibration Test ◽  
Complementary Part

This paper reports the step-by-step procedures of a full-scale ambient vibration test and the corresponding modal identification and Bayesian structural model updating of a coupled building. The building is characterized as a combination of a main part and a complementary part connected together by corridors in between. Compared with the main part, the volume of the complementary part is much smaller. Therefore, the influence on the dynamic properties of the complementary part from its counterpart is expected. To capture the dynamic properties of the coupled building, a 21-setup ambient vibration test was designed to cover all the degrees of freedom (DOFs) of interest. The modal parameters of each setup were identified following the frequency domain decomposition (FDD) method and the partial mode shapes from different setups were assembled following a least-squares method. To determine the stiffness of the linkage between the two parts, the coupled building was simulated with two linked shear buildings and updated utilizing the Markov chain Monte Carlo (MCMC)-based Bayesian model updating method. The identified modal parameters revealed interesting features about the coupled effects between the main part and complementary part and were discussed in detail. The good match between the model-predicted and identified modal parameters verified the validity of proposed shear building model. This study provides valuable experience in the area of structural model updating and structural health monitoring.

Ambient vibration test results of the Imperial County Services Building

1983 ◽  
Vol 73 (6A) ◽  
pp. 1895-1902
Author(s):  
Gerard C. Pardoen
Keyword(s):  
Strong Motion ◽  
Ambient Vibration ◽  
Vibration Test ◽  
Test Results ◽  
Structural Failure ◽  
Imperial Valley ◽  
Ambient Vibration Test ◽  
Significant Interest ◽  
First Time ◽  
County Services

Abstract The ambient vibration test results conducted on the Imperial County Services Building prior to the 15 October 1979 Imperial Valley earthquake are summarized. These results are of significant interest because the Imperial County Services Building has been the source of many postearthquake investigations due to the fact that the 1979 earthquake represented the first time a building instrumented with strong motion recorders suffered and recorded the major structural failure.

scholarly journals Ambient Vibration Test on Reinforced Concrete Bridges

2016 ◽  
Vol 47 ◽  
pp. 02012 ◽  
Author(s):  
Nurul Shazwin Idris ◽  
Koh Heng Boon ◽  
Ahmad Fahmy Kamarudin ◽  
Sherliza Zaini Sooria
Keyword(s):  
Reinforced Concrete ◽  
Concrete Bridges ◽  
Ambient Vibration ◽  
Vibration Test ◽  
Ambient Vibration Test ◽  
Reinforced Concrete Bridges

scholarly journals A Review of Ambient Vibration Technique on Bridges

2015 ◽  
Vol 773-774 ◽  
pp. 1002-1006
Author(s):  
Nurul Shazwin Idris ◽  
H.B. Koh ◽  
Ahmad Fahmy Kamarudin
Keyword(s):  
Dynamic Characteristics ◽  
Ambient Vibration ◽  
Vibration Test ◽  
Dynamic Information ◽  
Ambient Vibration Test ◽  
Vibration Technique ◽  
Highly Sensitive ◽  
Sensitive Sensor ◽  
Non Destructive ◽  
Labour Time

Bridge is one of the important facilities use in daily life as bridge is built to span physical obstacles such as a body of water, valley or road for the purpose of providing passage over the obstacle. Various testing conducted on the bridge in order to know the dynamic characteristics of the bridges. One of popular testing use is ambient vibration test. Ambient vibration is a non-destructive test conducted using highly sensitive sensor. This testing is easy to be conduct with less labour, time and also cost. This paper aim to provide up to date literature review on ambient vibration test on bridge includes sources of ambient vibration, procedure of conducting the measurement and results from ambient vibration test. It is important to known the dynamic characteristics of the bridge especially to determine the dynamic response of the structure and also as dynamic information for seismic design.

Earthquake analysis of reinorced concrete minarets using ambient vibration test results

2008 ◽  
pp. n/a-n/a ◽  
Author(s):  
Alemdar Bayraktar ◽  
Bariş Sevim ◽  
Ahmet Can Altunişik ◽  
Temel Türker
Keyword(s):  
Ambient Vibration ◽  
Vibration Test ◽  
Test Results ◽  
Ambient Vibration Test

Extending Blind Modal Identification to the Underdetermined Case for Ambient Vibration

2012 ◽  
Author(s):  
Scot McNeill
Keyword(s):  
Natural Frequencies ◽  
Second Order ◽  
Modal Identification ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Frequency Domain Method ◽  
Blind Identification ◽  
Vibration Data ◽  
Modal Damping ◽  
Six Dof

The modal identification framework known as Blind Modal Identification (BMID) has recently been developed, drawing on techniques from Blind Source Separation (BSS). Therein, a BSS algorithm known as Second Order Blind Identification (SOBI) was adapted to solve the Modal IDentification (MID) problem. One of the drawbacks of the technique is that the number of modes identified must be less than the number of sensors used to measure the vibration of the equipment or structure. In this paper, an extension of the BMID method is presented for the underdetermined case, where the number of sensors is less than the number of modes to be identified. The analytic signal formed from measured vibration data is formed and the Second Order Blind Identification of Underdetermined Mixtures (SOBIUM) algorithm is applied to estimate the complex-valued modes and modal response autocorrelation functions. The natural frequencies and modal damping ratios are then estimated from the corresponding modal auto spectral density functions using a simple Single Degree Of Freedom (SDOF), frequency-domain method. Theoretical limitations on the number of modes identified given the number of sensors are provided. The method is demonstrated using a simulated six DOF mass-spring-dashpot system excited by white noise, where displacement at four of the six DOF is measured. All six modes are successfully identified using data from only four sensors. The method is also applied to a more realistic simulation of ambient building vibration. Seven modes in the bandwidth of interest are successfully identified using acceleration data from only five DOF. In both examples, the identified modal parameters (natural frequencies, mode shapes, modal damping ratios) are compared to the analytical parameters and are demonstrated to be of good quality.

Structural System Identification of Elevated Steel Water Tank Using Ambient Vibration Test and Calibration of Numerical Model

2020 ◽  
Vol 20 (10) ◽  
pp. 2071010
Author(s):  
Mohammad Alembagheri ◽  
Maria Rashidi ◽  
Mohammad Seyedkazemi
Keyword(s):  
System Identification ◽  
Numerical Model ◽  
Dynamic Properties ◽  
Ambient Vibration ◽  
Water Tank ◽  
Ambient Vibration Test ◽  
Vibration Data ◽  
Steel Material ◽  
Ambient Vibration Testing ◽  
Structural System Identification

This research aims to investigate the feasibility of using ambient vibration testing for system identification of an elevated water tank. To identify the natural dynamic properties, the experimental study is carried out on an elevated steel water tank located in Tehran. The tank is instrumented with a sensitive velocimeter sensor (microtremor), and the ambient velocity of the tank is recorded for 30[Formula: see text]min in three orthogonal axes. Employing the peak-picking method in the frequency domain, the fundamental frequency of the tank is determined as about 1.9[Formula: see text]Hz. Then, the numerical model of the tank is generated and calibrated based on the obtained data. In the primary modeling, the values of natural frequencies of the tank are in good agreement with the results of the ambient vibration data. This finding is judged to be reasonable considering no clear sign of corrosion in the steel material.

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