Comparison of methods for analysis of structural systems under sudden removal of a member

Abstract

The paper provides the conclusions of a comparative analysis of various approaches, design models, methods for analysis of a loaded structural system and the results of such analysis for a sudden failure of a structural member. It shows that the analysis methods recommended by Russian and foreign standards are based on the same methodology. And the recommended options for choosing secondary design schemes in static, quasi-static and dynamic formulations have different complexity, however, give results which are close enough and acceptable for practical purposes. Some differences in the results are associated with different approaches to consider the reaction redistribution time for the removed structural member, i.e., in essence, with the mode of failure of this member. The issue of criteria for a special limiting state is also discussed. The authors present the expediency of including an additional criterion in regulatory documents that considers the second-order effects on the buckling of the structural elements under accidental impacts and, accordingly, provisions for protecting structural systems against the exhaustion of the bearing capacity due to the loss of stability. As such criterion, the achievement of the limiting equilibrium point on the diagram “axial force vs. transverse deflection” can be adopted.

Keywords

• progressive collapse
• design model
• dynamic analysis
• quasi-static analysis
• dynamic loading
• material nonlinearity
• second-order analysis
• buckling