Determination of thermal stress in concrete pavements by means of measurement of in‐situ strains

Abstract

A new method of determining the thermal stress of concrete pavement in‐situ has been developed and applied to engineering practice with success. It consists of three parts:1. A system of theorems was established on the basis of mathematical modelisation that both temperature and thermal strain were sine functions of t, the time of observation, owing to the daily fluctuations of temperature and consequently the corresponding thermal strain. It was found that there exist a time phase and an angle of axes rotation between temperature and thermal strain.2. A bridge circuit with a strain block and specially designed equipment ‘free body’ was introduced. The strain transducer for every test point consists of one strain gauge in the strain block and one in the ‘free body’, the former is used as the active gauge in the bridge circuit and the latter as the dummy. A temperature probe of resistance type was inserted nearby each of the gauges. Arrangement of observations and procedure of the data treatment were stated.