Design And Effect Analysis Of Ultra Low Cycle Fatigue Text For Steel Pipe System With Bolt-and-Ball Joints

Bolt ball grid structure system is widely used in many large public b uildings,in addition to the function of daily public activities,but also as sume the function of earthquake shelters,studies have shown that this typ e of building will show severe ultra-low cycle fatigue under strong earthq uakes.Destruction phenomenon,due to the ultra-low cycle fatigue mechan ism under the earthquake of the steel structure of the building and the th eory is not yet mature,it is very necessary to carry out the experimental research on the ultra-low cycle fatigue performance of the bolt-ball joint s teel pipe system.This paper relies on the National Natural Science Foundation of China's?Research on ultra-low-cycle fatigue performance and assessment methods of bolt-ball grid structures under strong earthquakes ?(51578385)to conduct experimental research on the ultra-low cycle fatigue performance of the bolt-ball-and-tube joint assemblies.Summarized as follows:A set of highly efficient and stable test loading device was designed,that is,under the reaction force frame,through the FCS electro-hydraulic servo structure test system,the force-displacement hybrid loading method was used to perform large-displacement cyclic reciprocating load on the high-strength bolt tube ball assembly components.Under the effect of ultra-low cycle fatigue test,and through the adjustable length of the three-way support to ensure that themember axis force.A bolted steel pipe assembly member for ultra-low cycle fatigue test was designed.The quality and accuracy of the test piece meet the test requirements.A data acquisition system suitable for ultra-low cycle fatigue test of building steel structures was designed.It passed FCS electro-hydraulic servo structure test system feedback device,Artec EVA 3D scanner,NST-360 R total station,vernier caliper,GM130 thickNess gauge High-definition cameras and other means collected information on component failure modes,rod end-to-end displacements,rod-member space deformation patterns,elliptical deformation of steel pipe sections,horizontal lateral displacement of components,variation of component fracture wall thickNess,and fatigue fracture morphology.data.The calibration and accuracy verification of the deformation of the component space,rod deformation,horizontal displacement,circular steel section elliptical deformation and wall thickNess change of the round steel pipe member were carried out to verify the proposed data acquisition system.Accuracy.By analyzing the damage patterns of the specimen loading system and the collected data,we further validate the feasibility of the proposed test method and data acquisition system.