Characteristics of Grade 60 and Grade 72.5 Re-bars in Pakistan
In Pakistan, quality assurance of re-bars is practically non-existent and there is no generally accepted testing method for testing of re-bars. Steel re-bars of Grade 60 are exclusively used in Pakistan; however production of high strength re-bars has recently started. In this study, thirty samples of steel re-bars of Grade 60 and thirty samples of Grade 72.5 were tested using ASTM standard testing protocol to obtain the stress-strain curves and comparisons were made between the experimental results of Grade 60 and Grade 72.5 re-bars. It can be concluded that Grade 72.5 steel shows less deformation capacity as compared to Grade 60 steel. For Grade 60 re-bars, the yield strengths of all individual re-bars were much higher than the prescribed minimum yield strength, i.e. 60 ksi. For the Grade 72.5 rebars, about 50 % of the re-bars did not reach the prescribed minimum yield strength of 72.5 ksi. The experimental curves were then compared with an idealized stress-strain curve developed by using a fractional equation. It is recommended that instead of producing Grade 72.5 ksi reinforcing bars, the traditional ASTM Grade 75 reinforcing bars be produced.
COMPLETE STRESS-STRAIN CURVE OF CONCRETE AND NONLINEAR DESIGN
Difficulties of experimentally obtaining the descending part of the stress-strain curve of concrete in uniaxial compression and methods of overcoming these difficulties are described. The influence of testing parameters on the stress-strain curves are presented. Based on the experimentally observed stress-strain relationship, an analytical model was developed to predict the moment-curvature relationships of reinforced concrete sections. These moment-curvature relationships are compared with some available experimental data obtained and with those obtained by two other analytical models.
Ethics and the Treatment of the Mentally Ill, Homeless Person: a Perspective on Psychiatry Resident Training
ObjectiveThe authors outline the unique ethical challenges that psychiatry residents face in working with individuals who are homeless and mentally ill. The authors also propose steps to develop effective teaching methods with residents working with these patients.MethodsThe authors reviewed literature relevant to the training of psychiatry residents in ethics and treating individuals who are homeless and mentally ill.ResultsThe authors summarize current literature and, with the use of case examples, provide guidelines for effective teaching.ConclusionsTeaching psychiatry residents who are working in the community with individuals who are mentally ill and homeless needs to address a number of unique ethical conflicts that arise in this area. The authors outline approaches to this teaching.