Research For Convection Heat Transfer On The Surface Of Concrete Structure

Thermal stress caused by difference in temperature can reach or exceed live load and turn into main factor for structural cracks in concrete structure or statically indeterminate structural system. The influence of sunlight radiation brings about difference in temperature on the structure and causes structure failure during service life, and the convection heat transfer caused by sunlight radiation is an important aspect when analyzing the thermal effect on the concrete structure. Nowadays, the research about concrete's convection heat transfer still has not a reliable method and uniform formula. In this paper, four concrete column elements were devised according to the convection heat transfer and boundary theories, and their surface roughness was same to big mould board structure. The research of convection heat transfer on the surface of concrete column was carried out in wind tunnel laboratory of Tongji University, and the analysis of the rule of heat transfer with the effect of different wind speeds (from 1m/s to 25m/s) and difference in temperature was emphasized. Through the experiment, the formula of experimental result for heat coefficients is given through calculating the heat coefficients on the surface of concrete column. Through applying the finite element method of thermal effect analyzing, the nature and force states for four concrete column elements were analyzed, the conclusion that the calculated temperature distribution from finite element method keeping consistent with the experimental measure-result is gained. Because the convection heat transfer of concrete structure endures the influence of environmental change all the time, thus the research theories of some scholars and the experimental results were analyzed and compared according to the structural real instance of natural condition. The formulas of convection heat transfer and general heat transfer coefficients for common concrete structures are given, and they provide gist for analyzing thermal effect of concrete structures.