Research On Thermal Insulation And Mechanical Properties Of Cantilever Balcony Plate With Broken Thermal Bridge Connectors

At present,the global ecological energy problem is becoming more and more prominent.Countries around the world are actively promoting the development of building energy conservation.Energy-saving concepts such as ’ passive houses ’ and ’ near-zero-energy buildings ’ have been proposed one after another.Countries are also aiming at building zeroenergy buildings.The balcony is the only important component structure that runs through the interior and exterior of the building in the enclosure system.Improving the thermal insulation level at the node of the balcony plate is one of the important measures to reduce the building energy consumption and achieve the goal of energy saving and emission reduction.Aiming at the common insulation problem of balcony plate,this paper proposes a new type of cantilever balcony plate structure with heat-break bridge.The structure uses heat-break bridge connectors and high-strength compression test blocks to connect the balcony plate with the main floor,and the joints are filled with insulation materials.The structure not only avoids the on-site pouring,but also has the advantages of simple structure design,short construction period and strong thermal insulation performance.In this paper,three methods of experimental research,finite element numerical simulation and theoretical calculation and analysis will be used to analyze the balcony plate structure.The main work and conclusions are as follows:(1)The finite element simulation analysis and comparison of the ordinary cantilevered balcony plate structure and the designed new heat-break bridge cantilevered balcony plate structure are carried out under the same steady-state temperature field.The ABAQUS software is used to establish the temperature field of the cantilevered balcony plate of different structural forms.The corresponding theoretical formula is used to calculate the linear thermal bridge coefficient at the node of the cantilevered balcony plate of different structural forms for thermal evaluation.The results show that the new type of heat-break bridge cantilevered balcony has little effect on the thermal insulation performance by using different kinds of connectors.Compared with the ordinary balcony plate,the new type of heat-break bridge cantilevered balcony plate designed in this paper has a lower linear thermal bridge coefficient at the heat-break bridge node,which can better reduce the loss of local thermal bridge heat and has better thermal insulation and energy saving effect.(2)Static loading tests were carried out on a new type of cantilevered balcony plate structure with two different material connectors.The failure process,load deflection curve,crack distribution,yield point position and stress-strain relationship of the specimens were studied,and the deformation capacity reserve and bearing capacity reserve were evaluated.The results show that the average bearing capacity reserve and the average deformation reserve capacity of the new type of heat-break bridge cantilever balcony plate with various types of connectors are high,and the new type of heat-break bridge cantilever balcony plate has sufficient safety reserve capacity.The type of connectors and the type of high-pressure test block have a great influence on the ultimate bearing capacity of the specimen,the distribution of cracks on the surface of the balcony plate and the overall stiffness of the specimen.(3)Considering the influence of different parameters at the joints of the heat-break bridge on the ultimate bearing capacity of the cantilevered balcony plate of the new heat-break bridge,parametric analysis is carried out.The test results were compared with the simulation results,and the changes of the yield point,stiffness and load-deflection curves of the specimens were analyzed.The results show that the experimental results are in good agreement with the numerical simulation results.The ultimate bearing capacity of the new cantilevered balcony slab can be improved by reducing the width of the insulation material,increasing the radius of the connector and increasing the lateral compression area of a single high-strength compression test block.(4)The failure mode and stress mechanism of the cantilevered balcony plate joints of the new heat-break bridge were analyzed.The theoretical calculation formulas for cracking load,yield load and ultimate load of cantilever balcony plate structure of new heat-break bridge are established.The calculation results show that the experimental results are close to the theoretical calculation results,and the average deviation is above 0.90,which indicates that the theoretical formula is suitable for the new type of cantilevered balcony structure with heatbreak bridge.