Damage Identification Research Of Grid Structure Based On Dynamic Strain In Temperature Effect

Space grid structures are widely used in actual projects. Most of space gridstructures are used as public buildings, so special attention is needed for their safety. Itis very difficult for damage identification and health monitoring to space gridstructures because the volumes of them are very huge and structural members arequite large. It is inappropriate to identify damage by using overall damage index ormodel updating of the whole structure. In order to identify the local damage of spacegrid structure, local index is studied and the applicability of the local index underenvironmental factors is also considered. Based on the above considerations, thecharacteristics of the ambient temperature and its effect on space grid structure arestudied firstly. The results of damage identification are investigated based on thedynamic strain information. Identification results are verified by actually test data.The detailed research contents of this paper are shown as follows:(1)The characteristics of temperatures in Guangzhou are analyzed. Theassociation of long-term temperature effects and the strain response of space gridstructure is established through the annual temperature and diurnal temperature effect.(2) Different damage cases are considered for typical grid structure. The damageidentification of grid structure is studied by using the strain modal and the strainwavelet packet decomposition as damage indexes. The applicability of this twodamage identification methods to grid structure are investigated under the influence ofthe ambient temperature.(3) Because of the huge volume of large space structure and the difficulty ofobtaining dynamical characteristics under the influence of environment, the method ofthe strain response wavelet energy for identifying damage of the elements is proposed.The effect of damage identification method is verified by actual projects.The above investigations indicate that: the parameters of the dynamic strain based on the methods of the difference of strain modal and the strain response waveletenergy can effectively indicate the damage members in grid structure, and the effectunder environmental temperature is small; Effectiveness of the method of the strainresponse wavelet energy which can indicate the local change of large space structuresis verified by actual projects.