Work Shaped Steel Members Under Cyclic Loading Plane Buckling Analysis And Seismic Design Of Countermeasures

Owing to a lack of the knowledge of the coIlapse mechanism of steel structures underseismic action, the plate element with the width-thickness ratio of plastic design according toDesign Code of Steel Strutures (GBJl7-88), which can meet plastic deformation demand understatic loading, can not develop plastic deformation thoroughly under cyclic loading. The typicaldamages such as locai buckling, brittle fracture and low cyclic fatigue usually take place in someregions of the world. So the analyses of respons and collapes mechanism of steel structuresunder cyclic loading are not ouly of theordtical significance but also of practical importance.Considering the requirement of a precise stress-strain relationship, a new constitutivemode-the elastoplastic anisotropic damage model of the constructional metal is put forward,which includes the mixed hardening criterion, Bauschinger effect, yield plateau, hardening(softening)influence, damage and damage evolution.Based on the constitutive relations and the 8-node degenerate shell element, the updatedLagrange (U.L.) formulations for FEM analyses are derived. After developing and debuggingprogram, the emphases are laid on the influences of slenderness ratios, width-thickness ratios andresidual stresses on the hysteretic characteristics of the I-beams.The Interaction formulas of thewidth-thickness and the lateral-torsional buckling strength are suggested.The influences of slendemess ratios, constant axial compression ratios and width-thicknessratios on the hysteretic characteristics of the I-section beam-columns subjected to constant axialcompressive force and cyclic bending moments are then investigated. The interaction formulasof maximum slenderness ratios and limit width-thickness ratios and out-of=plane bucklingstrength are established, respectively.The problem of interaction between local and overall buckling under seismic loading is ofgreat importance and complication for steel structure members made of thin plates by weldingand cold forming' There are W other fields Where researches muSt be done, and also othernroblems.