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Study On Mechanical Behavior And Theoretical Model Of Eccentric Steel Joints

Posted on:2018-11-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z J ShiFull Text:PDF
GTID:1362330566987933Subject:Civil engineering
Abstract/Summary:PDF Full Text Request
Eccentric steel joints with columns outside beams could satisfy the architectural requirments flexibily.However,due to the eccentric influence,a three dimensional torsion would occur in the panel zones,while the distorsion and warping would occur at beams' section.Moreover,the stiffness and the ultimate strength of the eccentric steel joints would be decreased significantly when compared with the concentric ones.This paper conducts a research on the mechanical behavior of the eccentric joints from the aspects of section,specimen and structure system respectively.The force mechanism,loaddisplacment curves,calculation method,spring model reprenting the core area and the applications in the elato-plastic dynamic analysis of structure systems are focused.The main achievements of the paper are depicted as following:(1)The static and quasi-static experiment of four eccentric steel joints are conducted.The cracking of weldings,yielding modes,load-displacement curves and the distribution of strains are obtained.Furthermore,the stiffness,ultimate strength,deformation,enengy dissipation and the ductility of specimens are analyzed.The FE models of the specmens are established while a parametric analysis is conducted.Design suggestions are proposed on the key plates.(2)The FE models are adopted to analyze the force mechanism and the strain's distribution from the section's aspect.The three dimensional torsion as well as the distorsion and warping are focused.A theoretical model and a simplified design method are proposed to consider the above two effects.The shear forces of the core area obtained are larger than those of concentric ones.Suggested formula is proposed for the shear forces and it is verified with acceptable precision.(3)The stiffness and the ultimate strength of the eccentric steel joints are investigated from the specimen's aspect.The comparison is conducted on the stiffness of the eccentric and the concentric joints.A theoretical model is proposed to predict the eccentric joints' stiffness,and the accruracy of the model is verified.The overall performance of eccentric steel joint is analyzed.The yied strength is classified into three categories,which are the shear yield strength,the torsion yield strength and the yield strength of beam and column's flanges.Suggested formula are proposed respectively,with a notable accuracy.(4)The spring model reprenting the core area and the multi-dimensional modelling method are proposed from the structure's aspect.They are applied to the static and elastoplastic dynamic analysis of a 10 story frame with the eccentric steel joints.The influence of eccentricity on the structure's performace is analyzed,including the maximum top displacement,the story drift and the joints' yielding mode.The accuracy and the efficiency are compared between different modeling methods.
Keywords/Search Tags:steel joint, eccentricity, torsion, distorsion and warping, spring model
PDF Full Text Request
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