STAINLESS STEEL IN FIRE (SSIF) - Steel-stainless.org

A summary of mean values of Design model/FEA and coefficients of variation (COV) are presented inTable 5.9 below. Equivalent mean values for the current design method in EN 1993-1-2 are also shown.Table 5.9Mean values and coefficients of variation for different design models for allClass 4 cross-sections included in the parametric study.Load level 30 % 40 % 50 % All load levelsMean COV Mean COV Mean COV Mean COVEN 1993-1-2 0.76 0.10 0.74 0.09 0.73 0.08 0.74 0.10Design Manual [2] 0.97 0.15 0.95 0.14 0.94 0.14 0.96 0.17Proposed newmethod1.01 0.08 0.99 0.08 0.98 0.11 0.99 0.12It is clear that the proposed design model gives improved predictions of the failure loads.The results of a variety of further simulations suggest that the proposed design model can be used fordifferent stainless steel grades.1.41.3N u,FEA/N u,c1.21.110.90.8FEA+10%-10%lambda-1lambda-2lambda-3L=31000.70.60 1 2 3 4 5 6 7Figure 5.4Comparison of the proposed design model and FEA at elevatedtemperature, 50 % load level5.4 ConclusionsA programme of tests on RHS with slender (Class 4) cross-sections was performed. Numerical modelswere calibrated against test results and then parametric studies carried out to develop more economicdesign guidance than is currently in existing guidance. The proposed model uses the room temperaturebuckling curve with the global, local and limiting slendernesses all being related to the temperaturedependentratio of strength and stiffness. The analysis of 3.1 m long pinned columns in a standard fireshows that it is possible for unprotected Class 4 stainless steel columns to achieve 30 minutes fireresistance if the load level is low.48