Predicting deflections of a simply supported pre-stressed concrete girder subjected to static loads from observed strains

摘要

Deflections of structures, such as bridge girders, are often the most difficult to monitor. Strain measurement is relatively simple with the use of electronic strain gauges, fiber optic sensors, or other strain measuring devices. This paper investigates two different methods for predicting or monitoring the deflection of a simply-supported full-scale bridge girder subjected to a partially distributed uniform load using strain measurements. A full-scale pre-stressed concrete bridge girder was instrumented and tested under a static monotonic load in the linear elastic range. This paper highlights the experimentally measured deflections along the length of one half of the girder and compares them to theoretically predicted deflections and deflections predicted using numerical integration along with harmonic analysis of curvatures determined from theoretical and observed experimental strains. Experimental test results indicate that estimating deflections from observed strains is feasible within the linear-elastic range of such girders. The methods outlined for predicting deflections of full-scale pre-stressed concrete bridge girders from observed strains are a valuable tool for structural engineers and for the periodic and continuous monitoring of civil structures such as bridges.