DAMAGE ASSESSMENT OF JACKETED RC COLUMNS USING VIBRATION TESTS

Damage assessment of reinforced concrete (RC) columns retrofitted by advanced composite jackets was experimentally and analytically studied. The writers built two half-scale bridge columns, wrapped them with the composite jackets, and subjected them to cyclic loading to introduce moderate and severe levels of damage to the columns. Vibration tests using a shaker were performed on these columns before and after jacketing and under undamaged and damaged conditions. The neural network technique was effective in estimating change (representative of damage) in the stiffness based on the measured vibration characteristics. The frequencies and mode shapes of the columns determined from the vibration tests and computed on the basis of the estimated stiffness showed excellent agreement. Pertinent to the purpose of the present study is the success of quantification of the extent and location of stiffness degradation due to different levels of damage. Degradation of the shear stiffness as well as the flexural stiffness in the lap splice region, especially in the 1-in. unwrapped gap portion, of the column was a key parameter to represent the damage.

[1]  Ahmet E. Aktan,et al.  Localized identification of constructed facilities , 1991 .

[2]  Norris Stubbs,et al.  Damage Localization in Structures Without Baseline Modal Parameters , 1996 .

[3]  James H. Garrett,et al.  Use of neural networks in detection of structural damage , 1992 .

[4]  M. J. N. Priestley.  The Whittier Narrows, California Earthquake of October 1, 1987—Damage to the I-5/I-605 Separator , 1988 .

[5]  Prabhat Hajela,et al.  Damage Detection in Structures Based on Feature‐Sensitive Neural Networks , 1994 .

[6]  Y. Deger,et al.  Modal Analysis of a Highway Bridge: Experiment, Finite Element Analysis and Link , 1995 .

[7]  C. Farrar,et al.  Damage detection algorithms applied to experimental modal data from the I-40 Bridge , 1996 .

[8]  Ahmet E. Aktan,et al.  FLEXIBILITY BY MULTIREFERENCE IMPACT TESTING FOR BRIDGE DIAGNOSTICS , 1992 .

[9]  Poyu Tsou,et al.  Structural damage detection and identification using neural networks , 1993 .

[10]  Ian G. Buckle.  The Northridge, California earthquake of January 17, 1994 : Perfomance of highway bridges , 1994 .

[11]  F. Seible,et al.  SEISMIC RETROFIT OF CIRCULAR BRIDGE COLUMNS FOR ENHANCED FLEXURAL PERFORMANCE , 1991 .

[12]  Pc Pandey,et al.  Multilayer perceptron in damage detection of bridge structures , 1995 .

[13]  Mjn Priestley,et al.  Seismic Design and Retrofit of Bridges , 1996 .

[14]  Maria Q. Feng,et al.  Cyclic Qualification Testing of Jacketed Bridge Columns in Flexure and Shear (26. Civil Structures-Bridges) , 1998 .

[15]  Arthur J. Helmicki,et al.  Structural Identification for Condition Assessment: Experimental Arts , 1997 .

[16]  Genki Yagawa,et al.  NEW REGULARIZATION BY TRANSFORMATION FOR NEURAL NETWORK BASED INVERSE ANALYSES AND ITS APPLICATION TO STRUCTURE IDENTIFICATION , 1996 .