Elastic-plastic Buckling Analysis Of Suspen-dome

Combined finite element animation with mechanical conception，author studied somefactors，such as connection rigidity，nonlinearity of material，initial deficiency，level ofprestress，density of grid，initial curves of member and configuration of circular cable，andput forward some suggestions for structural analysis in technical design stage.Then basedon conceptual analysis，author studied principles of nodal load-deflection curves，structureoverall load-deflection feature and distribution of element stress. Major conclusions are asfollows:1) Features of distribution of deformation and stress of suspen-dome can be explainedby model of ‘arch with tied-rod’.Like differences between under-reinforced beam andover-reinforced beam，suspen-dome can be divided into two types:under-cabled beam andover-cabled.2) Bearing capacity of under-cabled suspen-dome was determined by strength ofcircular cable.nonlinearity of this type is not strong，and its bearing capacity is proportionalto distance between arch top and circular cables.Influence of initial deficiency is notobvious.Influence of level of prestress force to bearing capacity and structural stiffness isnot that obvious also.The difference is that， the more prestress， the more reversedeformation.3) Bearing capacity of over-cabled suspen-dome was determined by strength of singlelayer dome.nonlinearity of this type is pretty strong.Influence of initial deficiency is prettyobvious.Influence of level of prestress force to initial structural stiffness is not that obviousalso，but higher prestress can raise stiffness of later stage，and hensethe it can raise bearingcapacity.Both types can reduce deformation in service stage by increasing prestress force.4) Influence of initial deficiency can be considered by modified consistent imperfectbuckling analysis method.The more distribution of imperfection is close to middle stage ofthe whole deformation process，the more adverse influence to bearing capacity.Underadverse distribution of imperfection，bearing capacity decrease as size of imperfectionincrease.5) Technical specification for space frame structures assume that:geometricalnonlinearity bearing capacity is2.1times of elastic-plastic bearing capacity.But according toresults of author，this ratio is about1.6. So it is necessary to carry out elastic-plasticanalysis.6) Density of grid is critical to bearing capacity，and influence of initial curves can beoverlooked.7) As load rises，inner cable-strut system slacks and back out.So it can be omitted，andonly keep the outer ring.Cable-strut system can reduce the difference between circularmember and radial member，and make member force more even.