High precision strain gauge measurements in areas of high stress concentrations of orthotropic plated bridge decks

Abstract

The most critical part of the design of an orthotropic plated bridge deck is concerned with the fatigue resistance of the many welds in such a deck. Strain gauge measurements can constitute an important tool in acquiring better understanding of the complex stress field in the deck plate. However, to achieve this, the measurements need to be extremely precise since the gradient of the stress peaks shows rapid changes in the area under consideration and the influence zone for the stresses is extremely short. In addition, and since fatigue problems cannot be studied on scale models, the measurements need to be performed on full-scale models or on real prototype bridge decks subjected to real traffic load. Obviously, in these conditions, the use of strain gauges becomes far more difficult than it is in laboratory conditions. This article reports on two measurement series, carried out on recently built orthotropic plated bridge decks in Belgium. It details the practical implementation of the strain gauges and measurement apparatus and compares the strain results with finite element calculations to validate the precision of the measurements.