Research On The Performance Of The National Stadium’s Steel Structure Under Environmental Loads By Field Measurements

As the technology of structural design and construction develops, more and more long-span spatial structures appear at home and abroad, which mostly have long spans and complex structural systems, and that makes their performance under different kinds of loads an important problem. When the structure is in service, it has a high chance to be under some environmental loads such as temperature load, rain load, snow load and so on. There has been corresponding computation theory for each kind of the environmental loads, however, in the actual situation, there are still some uncertainty about how the environmental loads act on structures. The assumption of the loads’ action mode in theoretical calculation may not completely match those loads’ real state, relatively, field measurements are effective means to acquire the real state of the sturctures under kinds of environmental loads.If using wired sensing on long-span spatial structures, the arrangement of wires will be very complex while sensors are widely distributed on the structure because long-span spatial structures are always in huge size and have irregular shapes. As a result, few researches by field measurements have been implemented on long-span spatial structures. To overcome the disadvantages of wired sensing, our lab developed a field measuring system based on wireless sensing, and it was applied to the steel structure of the National Stadium for long-term measurements of stress and temperatue of different members on the structure. Based on the plenty of data by long-term filed measurements, this paper studied the performance of the structure under temperature load, rain load and snow load.Firstly, this paper analyzed the temperature distribution of the structure under different conditions to study the mechanism of temperature load. Then this paper did a research on the stress variation law of the structure under long-term temperature load, and according to the non-uniformity of the temperature field, the temperature load was decomposed into two parts:the annual temperature load which was uniformly distributed, and the load of non-uniform temperature field. Then a comparison was made between the effects of annual temperature load and the load of non-uniform temperature field. The results indicated some important conclusions which may had reference value for the consideration of temperature load in structural theoretical computation.By tracking and monitoring throughout the processes of a heavy rain and snowfall, the response of the structure under rain load and snow load was captured. Based on the results of research on the structure’s performance under temperature load, this paper took a certain method to exclude the influence of temperture load during the rainfall and snowfall, and extracted the additional stress caused by rain load and snow load, then studied how the rain load and snow load affect different parts of the structure.Finally, by comparing the structure stress variation under temperature load, rain load and snow load, this paper discussed the proportion of internal forces caused by different kinds of environmental loads, and summarized the performance of the structure under environmental loads.