Test Principle and Test Scheme of Longitudinal Force in Continuous Welded Rail Using Resistance Strain Gauge

To test longitudinal force in continuous welded rails (CWRs), based on the bi-directional strain approach, a new test scheme using resistance strain gage was proposed. The test principle was systematically presented,and the errors of different test schemes were compared by taking into account the thermal output of resistance strain gage and uneven temperature distribution on the same rail section. The results show that, firstly, the test error mainly comes from uneven temperature distribution on the rail section. Secondly, when testing the longitudinal or vertical strain in CWRs, the thermal output of resistance strain gage and the influence of the longitudinal and vertical constraints of rail on the thermal output must be considered. In addition, all longitudinal force test schemes with resistance strain gage can not directly separate temperature force from the additional expansion force. Finally, the proposed scheme can offset bending strain caused by loads without additional compensation plate, and when both sides of the rail web have 2 ℃ temperature difference, compared to the two existing test schemes, the measurement error is reduced by 84.0% and 60.3%, respectively.