DAMAGE DETECTION IN 4-STORY STEEL BRACED F RAMES USING RESIDUAL FORCES BASED ON WAVELET TRANSFORM

Wavelet transform, which wa s first introduced in 1980, is operating on a modified basis functions and makes them a new function. Wave let analysis capability using a new method to analysis the signals and time-frequency signal processing o ffers. By replacing the wavelet network rather than rigorous analysis, accurate operation will not reduce the computational time is reduced dramatically.( Roland, 2000). Wavelet analysis is an efficient tool to detect structural damages like cracks and stiffnes s degradation (Kim and Melhem, 2004).In this study, residual forces and damage detection procedure by wavelet tran sform of residual forces were described. A four story space frame with diagonal braces with several damage states was considered. For every state of damage mass and stiffness matrices, mode shapes and natural freqquencies were evaluated. Finally dynamic responses of structure were conducted under wavelet analysis an d for all cases, damages were successfully detected.After wavelet analysis on res ponses, wavelet analysis curves of residual forces showed peak points on degree of freedoms of damaged me mbers.The damage locations, when damage occurs, are easily determined simultaneo usly by the ridges in the residual forces based on wavelet tr ansform. The degrees-of-freedom that have larg e magnitudes in residual wavelet force (RWF) are associated with the potential damage members within the structure.

کلیدواژه ها:

Damage detection ، Resi dual force ، Wavelet transform ، Steel braced frame s ، Earthquake