Effects of material nonlinearity on the global analysis and stability of stainless steel frames

In structural frames, second order effects refer to the internal forces and moments that arise as a result of deformations under load (i.e. geometrical nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical load factor of the frame acr is greater than or equal to 10 for an elastic analysis, or greater than or equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-1-4 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the material will result in greater deformations as the material loses its stiffness. A study of the effects of material nonlinearity on the stability of stainless steel frames is presented herein. A series of different frame geometries and loading conditions are considered. Based on the findings, proposals for the treatment of the influence of material nonlinearity on the global analysis and design of stainless steel frames are presented.Peer ReviewedPostprint (author's final draft

A multi-disciplinary approach to assess the impact of global climate change on infrastructure in cold regions

Imperial College London is researching with BP some potential impacts of future climate change. BP has a significant number of facilities in cold high-latitude regions, where global climate models predict significant rises in air and ground surface temperature. This could impact on the state and extent of permafrost, potentially posing risks to facilities, infrastructure, and operations (ACIA 2005). The paper reviews the research, focusing on an exemplar study region in eastern Siberia. The key elements included: (1) Developing an approach to provide a best estimate of future climate change. (2) An engineering geological appraisal of the ground conditions in the study region. (3) Performing a parametric study of geothermal conditions in the study region using finite element thermal analyses. (4) Developing a Thermal-Hydraulic-Mechanical modeling approach for assessment of climate change impact on specific engineering facilities. (5) Developing a methodology for incorporating potential climate change considerations into engineering decision-making and design.Postprint (published version

DESIGNING STEEL AND COMPOSITE BUILDINGS TO RESIST PROGRESSIVE COLLAPSE

Abstract. Based on the study of actual events, together with relevant material from adjacent areas, the main features of Progressive Collapse are identified and the requirements for a practical design approach stated. The essentials of the Imperial College Robustness Assessment Framework are described and the methodology illustrated with results for a few illustrative examples. The focus throughout is on reconciling an approach that is sufficiently rigorous that it captures all the essential features with a methodology that is similar to that employed for conventional design assessments