Analysis of Strain Measurement Accuracy in WF Steel Beams Using Strain Gauges: An Experimental Study Based on Elastic Theory

Abstract : This study presents an experimental approach to measure flexural and shear strains in a WF 150.75.5.7 steel beam using strain gauges. The primary objective of this research is to evaluate the accuracy of strain measurements obtained from strain gauges and compare them with theoretical predictions based on elastic theory. The experiment was conducted on a simply supported beam with a span length of 3.7 meters, subjected to a central static load applied through a Universal Testing Machine (UTM). FLA-6-11 strain gauges were installed on the top and bottom flanges to record flexural strain, as well as diagonally on the beam web to capture shear strain. The experimental results showed that flexural strain measurements deviated less than 5% from theoretical predictions, whereas shear strain measurements deviated up to 14%, which is presumed to be caused by inaccuracies in strain gauge installation. This study indicates that strain gauges are highly effective for flexural strain measurement, but require careful installation to ensure reliability in shear strain measurement. The research also highlights the importance of experimental documentation on locally standardized steel profiles, particularly BJ37 grade steel, as a reference for validating laboratory structural testing methods.