Vertical Accelerations of Steel Crane Girders in Situ

摘要

The development of small scale wireless accelerometers have allowed for monitoring of steel structures in situ with out altering the patterns of use. In this paper the mid span vertical accelerations of thirty (30) overhead crane sup port steel girders have been measured. It must be emphasized that the working cranes are investigated during nor mal operation. The canes' capacity ranged from 3 to 87. 5tons. The structures varied in age, and condition. Each support girder was monitored continuously on average for approximately 30 minutes. The chances of a significant o ver-load event during this short time are thus negligibly small. Nonetheless the dynamic loading due to the motion of the cranes produced very large vertical accelerations in the support structures. Results showed that approximate ly one third of the crane girders considered had peak vertical accelerations greater than 4. 2g (42m/s2) , thus satura ting the sensor used. In general, for all crane girders measured, the peak vertical accelerations were greater than 0. 4g(4m/s2).