Performance of unstiffened compression elements

The elastic and inelastic local buckling and elastic postbuckling behavior of unstiffened elements in cold-formed steel members and their effects on bending of beams and overall flexural buckling of columns have been investigated. An analytical investigation of the elastic and inelastic local buckling and the elastic postbuckling behavior of unstiffened elements with an elastic rotational edge restraint has been carried out. Results of experiments on short columns, long columns and beams are presented and compared with the analytical solution. An effective width equation for the elastic postbuckling range of the unstiffened element behavior has been derived by modifying the analytical solution to include the effects of initial imperfections, as indicated by test results. An empirical effective width equation, having a format similar to the AISI effective width equation for stiffened elements, has also been presented. An equation for the inelastic compressive strain capacity of unstiffened element has been derived. On the basis of the equations derived, methods for calculating the strength of cold-formed beams and columns with unstiffened compression elements subject to local buckling, are presented

Local Buckling of Stiffened and Unstiffened Elements under Nonuniform Compression

Thin plates subjected to linearly varying inplane compression in one direction may undergo local buckling before failure. An analytical procedure is presented for evaluating the local buckling strength based on which equations for the local buckling stress of unstiffened and stiffened elements are presented

Core Loaded Thin-walled Sleeved Column System

In conventional columns, the load carrying capacity is governed by the yield strength of the material and its buckling strength. The yield strength of the compression member is governed by the mechanical property of the material and its area of cross section while its elastic buckling strength depends on the least flexural stiffness (EI) ofthe cross section and its effective unsupported length. The elastic flexural buckling strength of a compression member is given by the well known Euler equation. In practice the strength of conventional compression members is less than bot.h the yield strength and Euler buckling strength due to the effects of imperfections, residual stresses etc.(Bjorhovde(1988)). In this paper behaviour of a novel patented concept, referred to as core loaded thin-walled sleeved column system, is discussed

Role of Biotransformation Studies in Minimizing Metabolism-Related Liabilities in Drug Discovery

Metabolism-related liabilities continue to be a major cause of attrition for drug candidates in clinical development. Such problems may arise from the bioactivation of the parent compound to a reactive metabolite capable of modifying biological materials covalently or engaging in redox-cycling reactions leading to the formation of other toxicants. Alternatively, they may result from the formation of a major metabolite with systemic exposure and adverse pharmacological activity. To avert such problems, biotransformation studies are becoming increasingly important in guiding the refinement of a lead series during drug discovery and in characterizing lead candidates prior to clinical evaluation. This article provides an overview of the methods that are used to uncover metabolism-related liabilities in a pre-clinical setting and offers suggestions for reducing such liabilities via the modification of structural features that are used commonly in drug-like molecules