The Old Derrick Steel Truss Structure in Linear Buckling Analysis (Eigenvalue)

The old derrick steel truss structure had been found in imperfect structure such in some member loses and unsual bolt holes. The derrick structures were located in critical path room publics for instance the public transportation path and the electricity transmission networks. This research had a numerical model the single element linear buckling ( eigenvalue ) that were based on the finite element method. The derrick prototypes had been modeled in single element that had the largest axial compression load that was defined in the perfect model. The artificial circle holes were attached on the member then was defined in the imperfect model. The artificial circle hole as representative the unused bolt holes. The linear buckling analysis had been performed by utilizing the 3D frame and 3D solid idealization with the 6 buckling modes had been required. This research had also compared the single element buckling and the overall derrick structure buckling analysis. The results showed that the buckling capacity reduced due to the number of holes. The greates number had the lowest critical loads (P cr ) then had buckle early. The numerical buckling pattern had similarly with in the elastic buckling theory (Euler buckling) at every mode. The critical buckling stress was lower than the yielding stress for every models. The results also showed that the critical load of the single element was lower than the overall structure. However, considering the environmental load such in the seismic load then the overall derrick structure buckling failure had higher vulnerability than the single element buckling failure.