Experimental study on damage diagnosis of RC composite beam

Abstract

For finding out dynamic characteristics of U-shaped steel plate-concrete composite beam in difference state and application in structural condition assessment, the experience of static multi-stage loaded and unloaded were performed on three composite beams by uniformly distributed weights. After unloading dynamic test were carried out with pulse excitation. Then the recorded transfer function was calculated by modal software Mescope to obtain the modal parameters. Dynamic characteristics of the composite beam had been summed up. Repeated modal were given up of which the magnitude is bigger at the supports, meanwhile the steady modal parameters were taken on an evaluation basis. While the bond action of steel bar/plate and concrete in composite structures were stronger, the frequencies were higher and the values of damp ratio were smaller. Whereas: if the bond action was weak, the frequencies will become smaller and the values of damp ratio higher. The results indicated that modal parameters were dispersed at some level, but the changes of frequency and damp ratio with damage may serve as a structural damage indicators, the stable modal shapes was influenced slightly by damage, which can be used to determine true and false mode and would not be used to indicate structural damage.