Structural damage detectability using modal and ultrasonic approaches

Abstract An experimental and analytical study of the relation between local defect, in a steel structure, and its higher frequencies and higher modes is discussed. The structure is a plane steel frame, assembled of beams, joined together with bolted connections. Removing some bolts from a given connection simulates the damage. In the experiment, an impulse force induced structural vibrations. Effects of vibrations were shown by data from gages, measuring accelerations with a high accuracy. From the data, it could be observed, that mode shapes, for the healthy and damaged structures didn’t show any differences for low frequencies. Only modes around thirteen showed significant gap between picks of Frequency Response Functions, for healthy and damaged frame. Moreover, looking at mode shapes, it could be observed that structural configuration may have some influence on defects to be observable. This aspect is discussed in a separate section. The experiment performed on the whole structure allows finding the place where the defect is localized. However, it can’t give detailed information on the defect itself, here defect of a bolt. For finding it, an ultrasonic measurement of pre-tensioning forces in bolts was applied. It allowed not only to determine stresses in the bolt, but also to verify, if in the process of assembling the structure was not pre-stressed.

[1]  Bartlomiej Blachowski,et al.  EXPERIMENTAL VERIFICATION OF DAMAGE LOCATION TECHNIQUES FOR FRAME STRUCTURES ASSEMBLED USING BOLTED CONNECTIONS , 2015 .

[2]  Zubaidah Ismail,et al.  Damage detection in frame structures using damage locating vectors , 2013 .

[3]  Hazim M. Dwairi,et al.  System identification of steel framed structures with semi-rigid connections , 2010 .

[4]  Gangbing Song,et al.  Review of Bolted Connection Monitoring , 2013, Int. J. Distributed Sens. Networks.

[5]  H. Hwang,et al.  IDENTIFICATION TECHNIQUES OF STRUCTURE CONNECTION PARAMETERS USING FREQUENCY RESPONSE FUNCTIONS , 1998 .

[6]  Chorng-Shyan Lin,et al.  Joint stiffness identification using FRF measurements , 2003 .

[7]  Yonghui An,et al.  A degree of dispersion‐based damage localization method , 2016 .

[8]  Michele Dilena,et al.  Vibrations of steel–concrete composite beams with partially degraded connection and applications to damage detection , 2009 .

[9]  S. Hao,et al.  I-35W Bridge Collapse , 2010 .

[10]  Bartłomiej Błachowski.  Model based predictive control of guyed mast vibration , 2007 .

[11]  W. D. Zhu,et al.  Detection of Damage in Space Frame Structures With L-Shaped Beams and Bolted Joints Using Changes in Natural Frequencies , 2013 .

[12]  Andrzej Świercz,et al.  Structural health monitoring of a railway truss bridge using vibration-based and ultrasonic methods , 2011 .

[13]  Chin-Hsiung Loh,et al.  Damage Identification of Bolt Connections in a Steel Frame , 2014 .

[14]  Miha Boltežar,et al.  Identification of the dynamic properties of joints using frequency response functions , 2008 .

[15]  Ibrahim N. Tansel,et al.  Evaluation of the health of riveted joints with active and passive structural health monitoring techniques , 2015 .