Thermal Stress Analysis Of Pre-stressed Concrete Roof

In practical projects, the roof is exposed to the external environment for a longtime. There will be some thermal stresses caused by the change of the environmenttemperature in the roof. Roof cracking because of thermal stresses has become thenormal quality problem in the projects. Luckily, the prestressing technology has agood performance in the crack resistance. With the development of the prestressingtechnology, especially the widespread use of the partially prestressing technology,more and more roofs are made of the prestressed concrete. However, crack control ofthis kind of roofs is still one of the most urgent things because of the temperaturefield. Therefore it is necessary to make some comprehensive analysis to thetemperature field of the prestressed concrete roof in order to get its stress distributionand the impacts of different factors. Consequently, we can reduce stresses and controlcracks in designs.The calculation of temperature field is determined when the chooseproper parameters.Based on the the existing researches of the temperature field, the article analysesthe temperature field, and deduces the differential equation of heat conduction of theplane temperature field and the solving method of the equation of the temperaturefield under the third boundary condition.At the same time, the article analyses atemperature field of a practical project with a finite element software namedABAQUS. The result demonstrates the feasibility of the software when used toanalyse the temperature field.In order to analyse the stress distribution of the roof under the different thermalloads preferably, this article not only introduces the finite element method of thecalculation of thermal stresses, but also the calculation of the shrinkage stresses underthe seasonal temperature loads with the equivalent frame method. With the use offinite element sofeware ABAQUS to analyse the stress distribution of the prestressingconcrete roof under different loads, discusses the prestress to stress on the distributionof the roof, at the same time,discuss influence to stress distribution under differentthermal loads of the arrangement of the prestressed reinforcing steel, the magnitude ofthe prestressing force, the change of the size of fascias and of the diameter of thenormal reinforcing steel.Based on practical engineering examples, the article analyses the stress distribution of the prestressing roof under different thermal loads, and demonstratesthe importance of the temperature field for the roof crack control.