| Nowadays, materials with high transmittance, like glass and membrane, are widely adopted as roof materials for large span space structures. Also, for some large span space structures, there would be structural components exposed to the outdoor environment. The influence of solar radiation on the temperature distribution of large span space structures should not be neglected in the above two cases. In addition, an interlayer may be added to a large span space structure with an architectural consideration, leading to the phenomenon called “incubator effect” which also has an influence on the structural temperature. The temperature distribution demonstrates a characteristic of non-uniformity and time-variation considering the coupling influence of solar radiation and air convection. However, in general the temperature effect on structures is considered as uniform in traditional structural design, which fails to meet the actual temperature distribution in structures, leading to potential safety hazard for both structural design and construction. This paper focuses on the non-uniform and time-varying temperature distribution in large span space structures considering the coupling effect of multi-fields including radiation, thermal and fluid.An experiment was conducted to investigate the effect of five different treatments on the reduction of maximum surface temperature of rectangular steel tubes. Results show that the temperature of a rectangular steel tube without any treatment could reach to 65.1? in hot summer, approximately 30? higher than ambient air temperature; Openings in the two lateral sides of steel tubes have a slight effect on reducing the maximum temperature, and envelop out of steel tubes can reduce the maximum temperature significantly. Actually, the three different treatments of envelop(steel box), i.e. porous box, enclosed box, and box containing thermal-insulation material, demonstrate a slight difference on the reduction of maximum temperature, and the maximum surface temperature values of the tubes are about 45?. The four walls of the steel tube placed in an envelope containing thermal insulation material keep uniform temperature values at any time in a day. Therefore, keeping steel tubes in a porous steel box could be a better solution for reducing the maximum surface temperature of steel members in large span space structures.The temperature distribution simulation of structures and members is conducted with FLUENT, a CFD numerical simulation software, to consider the coupling effect of radiation, thermal and fluid. The simulation results of the five enclosed rectangular steel tubes fit well with the measured temperature values, verifying the feasibility of the method. The application of this method is then extended to large span space structures with the wind speed at inlet is specifically defined by UDF, and the temperature distribution of large span space structures considering the coupling effect of solar radiation and air convection at different time points is obtained. The influences of architectural interlayers beneath large span space structures and glass roof on the temperature of large span space structures are also discussed in the paper. Results show that the “incubator” effect caused by architectural interlayers and glass roof can increase the maximum temperature of large span space structures by 7~10 ? and 2 ? respectively. Therefore, it is necessary to take the effect of architectural interlayers and glass roof into account when calculating the temperature effect in structural design.The formula for calculating the temperature effect provided by current Load Code for the Design of Building Structures and other relevant codes for structural design fails to take the influence of solar radiation into account. In this paper, a simplified method for calculating the temperature of steel members considering solar radiation is derived based on ASHRAE clear sky solar model and steady heat transfer theory. Also, an impact factor is put forward to consider the influence of wall conduction and surface radiation on the temperature of steel members. A comparison of the results calculated from the simplified formula and measured temperature values shows that the simplified method demonstrates a high accuracy with an error of less than 5%, which can satisfy the requirement of structural design well. |
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