Modal identification of Karun IV arch dam based on ambient vibration tests and seismic responses

This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012) and at the end of winter (March 2013), respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.

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Experimental evaluation of crack effects on the dynamic characteristics of a prototype arch dam using ambient vibration tests

Computers and Concrete ◽

10.12989/cac.2012.10.3.277 ◽

2012 ◽

Vol 10 (3) ◽

pp. 277-294 ◽

Cited By ~ 17

Author(s):

Baris Sevim ◽

Ahmet Can Altunisik ◽

Alemdar Bayraktar

Keyword(s):

Dynamic Characteristics ◽

Experimental Evaluation ◽

Arch Dam ◽

Ambient Vibration ◽

Ambient Vibration Tests ◽

Vibration Tests

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Blind Modal Identification of Non-Classically Damped Systems from Free or Ambient Vibration Records

Earthquake Spectra ◽

10.1193/031712eqs093m ◽

2013 ◽

Vol 29 (4) ◽

pp. 1137-1157 ◽

Cited By ~ 17

Author(s):

Fariba Abazarsa ◽

Fariborz Nateghi ◽

S. Farid Ghahari ◽

Ertugrul Taciroglu

Keyword(s):

Degrees Of Freedom ◽

Passive Control ◽

Modal Identification ◽

Ambient Vibration ◽

Mode Shapes ◽

Audio Signals ◽

Civil Structures ◽

Ambient Vibration Tests ◽

Vibration Tests ◽

Damped Systems

A significant segment of system identification literature on civil structures is devoted to response-only identification, simply because lack of measurements of input excitations for civil structures is a fairly common scenario. In recent years, several researchers have successfully adapted a second-order blind identification (SOBI) technique—a method originally developed for “blind source separation” of audio signals—to response-only identification of mechanical and civil structures. However, this development had been confined to fully instrumented classically damped systems. While several approaches have been proposed recently for extending SOBI to non-classically damped systems, they all require additional data such as velocity or analytic signals. Herein, we present a version of SOBI that requires only acceleration signals recorded during free or ambient vibration tests, and yields the system's complex mode shapes, natural frequencies, and damping ratios. Performance of the proposed technique is demonstrated through two synthetic examples: a ten-story structure possessing a passive control system, and a soil-structure system with seven degrees of freedom (seven-DOF).

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Experimental and Numerical Modal Identification of the Fossanova Gothic Cathedral

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.347.351 ◽

2007 ◽

Vol 347 ◽

pp. 351-358 ◽

Cited By ~ 3

Author(s):

Gianfranco de Matteis ◽

I. Langone ◽

Fabio Colanzi ◽

Federico M. Mazzolani

Keyword(s):

Seismic Vulnerability ◽

Dynamic Behaviour ◽

Shaking Table Test ◽

Mediterranean Area ◽

Modal Identification ◽

Shaking Table ◽

Ambient Vibration ◽

Dynamic Features ◽

Ambient Vibration Tests ◽

Vibration Tests

This paper focuses on the dynamic behaviour of the Fossanova cathedral (Latina, ITALY), which represents a magnificent example of pre-Gothic style church, whose structural typology is largely present in the Mediterranean area, especially in many Countries characterised by a High-Medium seismic hazard. In particular, within the European research project PROHITECH, aiming at investigating the seismic vulnerability of such a structural typology, experimental and numerical analyses have been carried out. Firstly, detailed investigations have been devoted to the identification of the geometry of the main constructional parts as well as of the mechanical features of the constituting materials of the cathedral. Then, both Ambient Vibration Tests (AVT) and Numerical Modal Identification analyses by Finite Element Method (FEM) have been applied, allowing the detection of the main dynamic features. Finally, a refined FEM model reproducing the dynamic behaviour of the cathedral by using scaled physical quantities according to the Buckingham theorem has been developed. In fact, the present study has to be intended as a preliminary activity devoted to se up a shaking table test on a reduced scale physical model of Fossanova cathedral, which will be shortly carried out at the IZIIS laboratory (Skopje, Macedonia).

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VULNERABILITY ASSESSMENT OF A CIVIC TOWER USING AMBIENT VIBRATION TESTS

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.2020.7(2).str-40 ◽

2020 ◽

Vol 7 (2) ◽

Author(s):

Gian Paolo Cimellaro ◽

Marco Domaneschi ◽

Ali Zamani Noori ◽

Valentina Villa

Keyword(s):

Vulnerability Assessment ◽

Modal Identification ◽

Ambient Vibration ◽

Experimental Investigations ◽

Collapse Mechanism ◽

Fe Model ◽

Dynamic Features ◽

Ambient Vibration Tests ◽

Vibration Tests ◽

Output Only

This paper focuses on the vulnerability assessment of a civic tower built in 1512, which is now considered a national monument. It is the original bell tower of S. Ambrogio church that was destroyed in 1809. Experimental investigations have been carried out on this historical tower. First, detailed investigations have been carried out to identify the geometry of the tower as well as the mechanical features of the constituting materials. Then, ambient vibration tests have been applied using five Micro Electro-Mechanical Systems (MEMS) sensors to detect of the main dynamic features, e.g., modal parameters and damping. Two output-only identification methods, including Frequency Domain Decomposition and Random Decrement Techniques, have been used. The outcomes of the modal identification have been employed to inform the FE model. The numerical analysis can be used for vulnerability assessment, providing a valuable picture of possible damage evolution, tower collapse mechanism, and subsequently, useful hints for the execution of structural retrofitting strategies.

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