Study On Thermal Insulation Performance Of Prefabricated Concrete Member Of Sandwich Wall

With the country vigorously promotes the concepts of green,environmental protection and low carbon,prefabricated buildings have become an important trend in the development of the construction industry today due to their high efficiency,high quality,fast construction speed,environmental protection and energy saving.Prefabricated concrete member of sandwich insulation wall is widely used as the insulation envelope structure of prefabricated buildings.Many scholars have carried out relatively perfect research on the seismic performance,unidirectional and multidirectional stress performance of this insulation wall and achieved rich results.However,there is a relatively lack of systematic research on the insulation performance of prefabricated sandwich insulation walls in practical applications and the effects of insulation materials and connectors on the overall insulation performance in prefabricated buildings.At present,most of the thermal insulation design and requirements in the project refer to local codes and related experience,and fail to prefabricate the corresponding components according to the characteristics of the building itself.Therefore,this article intends to study the thermal insulation performance of sandwich walls in fabricated concrete in conjunction with an actual engineering project,and proposes related improvement methods to further improve the thermal insulation performance of sandwich walls,mainly including the following work:(1)The thermal environment of the envelope of two different connections in the project is tested,the actual thermal insulation performance of the envelope structure is evaluated and analyzed;Through the test of the envelope structure to find the problems,and provide reference for the follow-up research.This article takes prefabricated concrete sandwich insulation wall in a project under construction as the main research object,and uses a temperature test instrument to measure the insulation performance of prefabricated maintenance members in the building.The test results show that both the FRP connector and the metal tie-down member have good thermal insulation performance,but both need to pass through the insulation layer to connect the inner and outer leaf walls,which destroys the integrity of the insulation layer and causes the wall's insulation performance to decrease;Compared with the FRP connector,the metal tie piece has stronger thermal conductivity in the prefabricated sandwich wall,which indicates that the performance of the prefabricated wall using the metal tie piece is slightly worse when the properties of the concrete and theinsulation material are similar.(2)Analyze the connectors used in the supporting structure of the project and point out the problems in the engineering maintenance structure.Calculate the thermal conductivity,heat transfer coefficient,and related coefficients of heat storage and other related coefficients according to the requirements of building codes in the area where the project is located to ensure that the building and related components meet local building energy requirements.The calculation results show that the shape factor of the building is 0.45 which is greater than the 0.3 specified in the code,so it is necessary to strengthen the insulation performance of the envelope structure.Combined with the related design of the enclosure structure in the project,the design and optimization of the thermal bridge problem at the corners and the joints of the panels and plates are adopted,and the thermal bridge effect in the building is reduced by adopting the method of extending the insulation layer.The theoretical calculation formula is used to calculate the thermal insulation performance of the precast concrete wall.Comparing the calculation result of the one-dimensional simplified formula with the actual measurement,the analysis results show that the metal connector will cause the thermal bridge.The calculation result of the one-dimensional formula cannot obviously reflect the thermal bridge effect in the wall and is less than the temperature.The actual measurement results are due to the existence of the connector.The heat transfer of the wall is no longer a simple one-dimensional heat transfer and the factors affecting the heat transfer caused by the heating environment of the building are more and more complex.The correction factor of the formula can be targeted The connection of different materials is modified to effectively improve the calculation accuracy of the insulation performance of the sandwich insulation wall.(3)For the target wall,CAD and revit software are used to build the model,and the model is imported into ANSYS finite element software for numerical simulation.Through the reasonable application of numerical simulation software,whether two different connectors will produce thermal bridge effect is analyzed.The results show that the metal connector will form a thermal bridge effect in the wall,and the effect on the thermal insulation performance of the wall is greater than that of the FRP connector.The temperature change law obtained by the software analysis is close to the actual temperature change in the field,which is about 10%,Combined with the measured results,the rationality and correctness of the use of ANSYS software are verified.The heat flux density and temperature change are obvious near the metal connector.Compared with the FRP connector,the average heat transfer coefficient of the wall is increased by about 35%,while the FRP connector has a good thermal insulation effect.There is no obvious thermal bridge.The improvement of the installation method of the metal connector can effectively reduce the influence of the thermal bridge effect on the wall.(4)Through the comparison of the research results obtained by the above experimental methods,the prefabricated sandwich insulation components and their connectors are analyzed and evaluated,and the problems existing in the actual construction of different components are analyzed and studied,and the improvement methods for the installation of metal connectors are proposed,The analysis shows that it can effectively reduce the effect of thermal bridge effect on the wall insulation performance.This thesis uses the methods of on-site environmental measurement,theoretical calculation and software simulation analysis to study and verify that the metal connectors have a greater impact on the wall insulation performance during the actual use of the building,and then use two types of pre-embedded and post-inserted Different installation methods improve the thermal insulation performance of the wall,so as to achieve the purpose of energy saving and thermal insulation in the actual building process.