Dynamic auscultation of beams

Abstract

In order to study experimentally the relation between level of the damage (cracking state) in a beam and its dynamic response (fundamental frecuency and damping) three series of beams have been tested: reinforced concrete, pretensiones and postensioned prestressed concrete. The beams were tested with increasing levels of damage by application of several states of bending efforts. After each load sollicitation state a dynamic test was leaded to measire the fundamental frecuency and damping. A clear decreasing in the values of fundamental frecuency as the level of damage increases has been reported in all the tests. The percentage of variation in reinforced beams is about two times the variation in pre o postensioned concrete. Logaritmic decrement, as a measure of damping, presents more scattered values but is clear the increasing of decrement with the severity of damage.