Study And Application Of Health Monitoring For Spatial Steel Structures Covered With Membrane

Long-span spatial structure is a kind of important public buildings, whose style is so graceful that become the symbol of the city. However, Long-span spatial structures have very complicated mechanics features, and cause serious economical losses and a very bad social influence once been destroyed. Structural health monitoring is a research hotspot in the field of civil engineering, which is an effective method for ensuring structural health and safety by installing sensor network and in real time grasping real loads and stress states of full size structures. In addition, a structure having a health monitoring system equals to a real field experiment system, which can reveal structural stress state and properties evolution laws during long-term operation and provide valuable information and scientific basis for structural analysis and development of design theory.This article, on the background of National Aquatics Center (" The water cube "), make a deep analysis on monitoring data after 4 years of construction and operation, and reveal loads and mechanics characteristics of the construction and operation periods to provide scientific basis for design and analysis of this kind of structures.The main contents of the paper are studied below:The design method of the construction unloading monitoring system and the heath monitoring system of the long-span structure covered with membrane are given, and which are designed for the National Aquatics Center.During the construction unloading in the National Aquatics Center, the strain responses of the structure bars and supporting system of which are monitored, with the results of the numerical simulation, the forced variation features of the structure and supporting system in the construction unloading are found out, and the optimization schemes on the assembling temperature and the construction unloading in the process of the construction are given through the optimizing analysis.The reason of effect of temperature on structures and temperature compensation based on Fiber Bragg Gratings (FBG) are studied on theoretic level. Based on the monitoring data from the National Aquatics Center, the distribution of temperature field are to be studied, the neural network model between the temperature and the structure strain responses are established, which is illustrating the temperature influencing regularity of the structure strains and time lag effect. On this basis, with monitored data of snow load and strain, gives a method for separating the snow strain. Finally, the laws of variation and distribution of temperature field, temperature strain and snow strain are studied based on measured data.Based on the monitoring data, structure damage identifying method based on the static statistic loading classification is built and prove the validity of this method. Based on the temperature influence theory on the structure, using the on-site monitoring date from the National Aquatics Center, the dynamic modal shape parameters sensitive regularity with the temperature is studied.The modal parameters of the ETFE air-inflated membrane structure covered the long-span structure are identified, and with the on-site monitoring and the mixed substructure method of the CFD numerical simulation, the pneumatic parameters of the air-inflated membrane structure are calculated, from which, the time-varying regularity and the variation regularity according to the wind speed of the pneumatic parameters are found.Through the statistic analysis on the environmental monitoring data from the National Aquatics Center, the distribution and variation regularities of the wind velocity, the wind direction, the wind pressure and so on are got, which will give the useful lessons for the wind resistance analysis and design of the similar structures.