Full-scale reinforced concrete bridge bent condition assessment using forced-vibration testing

摘要

Recent research has been conducted at Utah State University regarding the ability to assess the condition of a reinforced concrete bridge bent. Three full-scale, in-situ, reinforced concrete bridge bents were tested and modeled through varying states of damage. Each bent was initially tested in an undamaged state using a horizontal sine-sweep test. The forced-vibration testing was achieved using an eccentric mass shaker. The structures were tested in the frequencies ranging from 1.0 Hz to 20.0 Hz in increments of 0.05 Hz. A known amount of damage was inflicted upon each bent for two separate states. The sine-sweep test was re-administered for each damage state. The changes in dynamic characteristics, such as frequencies and mode shapes, were noted from state to state. Detailed finite element models were constructed to match the changes in dynamic characteristics of each bent for each state. This was achieved by matching the severity and location of the structural damage of the model to the field structures. Decreases in structural stiffness were detected with modal analysis. The models were consistent in matching the changes of the field structures. A method was devised for locating possible regions of structural damage.