Influence Of Thermal Insulation Material On Temperature Effect Of Concrete Thin-Walled Bridge Pylon Structure

Concrete is a commonly used civil engineering material,one of the obvious defects is poor thermal conductivity.Under the sunshine exposure,the inner and outer surfaces of the structure tend to large temperature differences.Consequently,a large thermal stress is generated inside and outside the structure,causing the structure to crack on the inner and outer surfaces,especially in the large-volume concrete structure.Therefore,it is an effective method to prevent the surface temperature crack of the concrete structure by sticking the thermal insulation materials to reduce the inner and outer surfaces temperature gradient of the concrete structure,thereby reducing thermal stress of the concrete structure.In this paper,Take a suspension bridge concrete pylon as the research object.The temperature field and thermal stress of concrete bridge pylon under different insulation materials are investigated by using finite element method and numerical analysis.Based on the analysis results,insulation effects of different insulation materials are evaluated.Firstly,using the three-dimensional model of the concrete box type pylon,the temperature field and stress field of the pylon structure under the sunshine temperature are simulated and analyzed.The results show that thermal stress between the inner and outer surfaces of the pylon structure is large as the result of the sunshine temperature difference,and its stress value is close to the standard value of tensile strength of concrete.Secondly,the temperature field and thermal stress distribution of externally polystyrene and polyurethane heat insulation panels with different thicknesses were studied and compared.After insulation,the maximum temperature difference between the inner and outer surfaces is reduced,thereby reducing the temperature stress.The results show that the thicker the insulation layer of the same kind of insulation board material,the better the insulation effect.When the thickness of the insulation layer is greater than 35mm,the temperature difference and the thermal stress value change slowly,and the heat insulation effect tends to be stable.Judging from the decrease of temperature difference and temperature stress value,the thermal insulation effect of polyurethane insulation board is better remarkable and superior to that of polystyrene insulation board.After using polyurethane insulation board for heat insulation,the temperature difference is reduced about 67%,the thermal stress is reduced by 30%.Then,the temperature field and thermal stress distribution of two kinds of thermal insulation coatings silicate thermal insulation coating and thermal insulation glazed hollow beads mortar were compared and analyzed.The results show that the thermal insulation effect of thermal insulation glazed hollow beads mortar is better than that of silicate thermal insulation coating.After using the thermal insulation glazed hollow beads mortar,the temperature difference is reduced by 40%,and the temperature stress is also reduced by 22%.The analysis of different colors of vitrified micro-bead insulation mortar,light color coating can effectively reduce the temperature difference and thermal stress value,the temperature difference is reduced by 49%the temperature stress value is reduced by 47%.Finally,a comprehensive evaluation of the characteristics,cost and effect of different thermal insulation materials is made in this study.The relevant conclusions provide a valuable reference for the design and construction of actual projects.