Study On The Mechanical Properties Of Oil Derrick Structure With Semi-rigid Joints

As important component for bear the loads during the exploration and development of the oilfield,derrick is the essential component of rig equipment in hoist system.Rig derrick,is always working at worse environment than the general steel structure,thanks to drilling operation often works is in vile condition in the open.In recent ten years,scientific research units of each big oilfield,colleges and universities and so on are using a variety of research methods for use in safety evaluation analysis of derrick structure,in order to guarantee the safety during the process of oilfield exploitation.At the moment,the general way of the safety assessment to oil derrick is that,testing derricks stress.displacement and structure dynamic characteristic,basing on testing data,making sure the bearing capacity of derricks by linear extrapolation.With the development of the finite element analysis,field testing and finite element simulation analysis of the derrick structure combining to become the main method.Derrick structure between the components,by connecting the assembled into the whole structure.The connection mode is generally divided into welding connection,pin Saddle-Ear plate connection and bolt connection.The connection mode and connection performance directly affects the structure of work properties.According to the connection joints of different stiffness,connection is divided into rigid connection,semi-rigid connection and articulated connection three types.Usually,finite element analysis for the oil derrick structure,the derrick structure connected between the considered as rigid form calculation.It is does not match the actual situation for many years of derrick in oil field,The calculation will inevitably bring about error results.This paper consider welding nodes as semi-rigid connection between column and transverse reinforcement,to study of semi rigid connection of derrick structure mechanical properties.This article first introduces the steel structure connection types of beam and column and its characteristics,semi-rigid beam column connections are introduced the research methods and mechanical properties.Aiming at the flexibility of the beam-to-column joints's connection has an effect on nonlinearity of the connection.The formulation of the semi-rigid beam element stiffness matrix for two-dimensional three-dimensional steel frame is given.The assembly method is used to to generate the overall initial stiffness of the weldingj oint,by comparison between the results of formula calculation and finite element analysis for welded joints,it was showed that the results between formula calculation and FEM have good match.Using spring element model with stiffness variation of double direction to simulation of the semi-rigid nodes,describes the specific implementation methods and steps.And the establishment a finite element model of derrick with semi-rigid connection.Study semi-rigid nodes of influence in internal the force and displacement of structure?the stability and dynamic characteristics of structure,and ultimate of load capacity for oil derrick structure.