Detection and analysis of deck cracks in a long span empirically designed bridge deck through embedded sensory systems [electronic resource] /

by Riad, Mourad Y.

DETECTION AND ANALYSIS OF DECK CRACKS IN A LONG SPAN EMPIRICALLY DESIGNED BRIDGE DECK THROUGH EMBEDDED SENSORY SYSTEMS Mourad Y. Riad Bridge decks exhibit premature longitudinal and transverse cracks leading to dramatic decrease in their service lives. Because of safety concerns, state highway agencies are overburdened by conducting annual visual inspections to detect signs of distresses in bridge elements and to provide continuous records of the conditions of such bridges. Those inspections are time consuming, and have multiple limitations which often yield controversial outputs. In this study, an instrumentation based system is designed and implemented on the Star City Bridge near Morgantown WV, to provide more sophisticated, and accurate methods to assess the structural performance of bridge elements, and hence provide a rational method of making decisions about the condition of such bridges. The instrumentation system consists of an array of more than 750 sensors that provide continuous records of the triaxial state of strains in the concrete deck, thermal map along the deck, opening of expansion joints at the bridge ends, steel girders bending moments and shearing stresses, axial forces in the bracing members and angle of inclination of the abutments. The traffic spectrum crossing the bridge is measured via a weigh-in-motion system installed at one bridge approach and a weather station is installed at the bridge proximity. An innovative approach for deck crack detection and monitoring is established and analytical evaluation of slip strains in the deck system is presented. The study involves detailed 3D finite element modeling of the multiple phases of construction, and reasons of concrete deck cracks are explained through analysis of the dynamic properties of the superstructure. Analysis of continuous time histories along 2 years showed that bridge decks are subjected to a variety of temperature gradients across the deck system that are not accounted for in design procedures.