Measurement of Temperature Distribution Within Steel Box Girder of Vistula River Bridge in Central Europe

Uneven temperature distribution in a structural element constitutes one of its load factors. Temperature fields occurring in structural elements lead to stresses and strains. The values of internal stresses are directly related to temperature distribution and degree of freedom for element deformation. The best way to get information about temperature distribution in an element is to take measurements on a real object. Such measurements have been run or are still taken over decades in various parts of the world, e.g. in Western Europe, USA, China, South America. In a number of cases, such examinations were carried out for objects constructed in warm or hot climate. It is a lot harder to find the results of measurements made in the countries with moderate and transitional climate, like in the Central or East-Central Europe. This paper presents measurement methodology and results gained for a large steel bridge located in the East European Plain, about 52.5° N northern latitude. Permanently installed contact sensors, temporary sensors, as well as pyrometry and thermography were used. An attempt was made to determine temperature distribution in a steel box girder of a bridge using thermovision technique. Approximate temperature distribution patterns in the main span girder were determined from thermal photographs taken. The most important results of examinations are the images of temperature fields in the main span girder related to solar radiation that first and foremost directly affects the bridge deck.