Research On Failure Modes Of Kiewitt-Lamella Suspendome Structure Under Localized Fire

As a large-span prestressed spatial steel structure, suspendom is formed by the combination of a single-layer reticulated shell and cable-struct system with reasonable force distribution and has made full use of two kinds of material. As a result, the suspendom structure has been used more and more widely.Recently, the research of suspendom is mainly on the design and construction stratigies, and study on the mechanical performance of the structure under high temperature is not comprehensive. The introduction of high strength prestressed cable in suspendom makes the fire hazard more sensitive, so the study on the fire resistance of suspendom needs to be carried out urgently. The research on the Kiewitt-Lamella suspendome structure contains the following.At first, based on and the actual engineering structure geometry, using the initial-strain method to tension radical cables, the Kiewitt- Lamella suspendome structure analysis model is established with ANSYS based on nonlinear finite element theory to confirm the reliability of the numerical analysis model. And the influence of rise-span ratio, prestress and loads for the mechanical performance of the structure is studied.Secondly, considering geometric nonlinearity and material nonlinearity, according to the step-by step temperature procedure method, using the bending component high temperature bearing capacity in CECS 200:2006 as the limit state of shell component, the axis-pressure component high temperature bearing capacity as the limit state of structse and the tensile strength bearing capacity as the limit state of steel cables, the element analysis model for the thermo-machanical coupling effects of suspendome structure is set up to study the mechanical performance and failure modes under uinform and non-uiform temperature fieldsThirdly, based on the non-uniform temperature field, load ratio, rise-span ratio, the characteristics of prestress, parameter analysis of suspendome structure under localized is carried out to study the stress process of elements, the critical temperature, the failure mode and provide reference working mechanism for the further study of suspendome structure under fire.The research demonstrates that the main deformation behavior of suspendom under lacalized fire is bulging deformation and collapsing deformation. The radius of fire is inappreciable to the critical temperature. The mian factors influencing the suspendom structure are non-uniform temperature field, load ratio, rise-span ratio, the prestress, the location of fire. The greater the non-uniform of the temperature field, the greater the suspendom’s critical temperature. In like manner, the greater the load ratio, the lower the suspendom’s critical temperature. The greater the rise-span ratio, the greater the suspendom’s critical temperature. The shorter distance from center of fire, the greater the suspendom’s critical temperature. The greater the prestress, the higher the suspendom’s critical temperature. The two mian failure modes of suspendom structures are that the outer ring cables’ fire ultimate bearing capacity decreases significantly or the outer ring shell elenments’ stress grows significantly to be destroyed, resulting in the overall structural failure.