Study On Dynamic Characteristics Of Oil Derrick Structure Based On Vibration Experiment Method

Currently, spatial rigid frames, such as buildings, bridges, platform, oil derricks have been more or less damaged caused by long-time fatigue, corrosion, etc in service, thus leading to poor structure or low performance. To guarantee the safety and avoid disaster, the scholars, engineers and technicians are paying attention to the research of identification for the damage of structure real-timely, on-line and accurately.This paper discusses present situation of structure damage identification techniques at home and abroad, and introduces various theory and research methods of structure damage identification techniques, and further applies modal parameter analysis to study on structure damage identification for oil derrick.In FEM analysis, the ANSYS software is first developed. After it, the member bars are simplified the three-dimensional beam elements base on the compositions of actual derrick structure. The computer numerical model is established and applied to analyze the dynamical characteristics of derrick structure, and the vibration mode are calculated. According to mode characteristics of oil derrick with different damage, displacement mode method and curvature mode method are applied to identify structure damage. Consequently, damage locations are identified by the displacement mode method, and the extent of damage is further identified by the curvature mode method.In the measure analysis, base on the uTekSs analysis platform, the lab derrick model is tested by high-capacity data acquisition dynamic testing system. The data measured are analyzed to identify structure damage. Both the displacement mode method and curvature mode method are used together to show the relationship of the extent of damage of oil derrick and dynamic parameters.So to evaluate derrick structure damage identification with modal parameters is proved practicability from FEM analysis and test analysis, which provides effective theoretical basis for real-time and on-line monitoring of oil derrick.