The influence of production routes on the behaviour of stainless steel structural members

Current structural design codes for stainless steel employ material strengths, or 0.2% proof stress values that are significantly lower than the 0.2% proof stress of material taken from stainless steel structural cross sections. This discrepancy is attributed to the ability of stainless steel to significantly cold work during plastic deformation, which occurs in sheet rolling and cross section forming processes. The resulting under-estimation of the material strength in stainless steel cross sections leads to overly conservative structural designs. As the comparative expense of stainless steel demands efficient design, this study proposes models to predict the strength enhancements offered by different cross section production routes to increase the efficiency of stainless steel structural design. This research project includes a substantial experimental program that has produced 0.2% proof stress distributions from over 450 tensile coupon tests for a total of 19 cross sections formed via three standard production routes: press braking, cold rolling and hot rolling. To obtain 0.2% proof stress variations to a higher resolution, Vickers hardness values have been obtained and correlated with the 0.2% proof stress values. Significant strength increases in the flat regions of cold rolled box sections have been found and related to the strain history of the sheet material used in production and the strain caused during section forming. Existing models to predict further strength enhancements in the comer regions have been modified and the extension of the region of cold work associated with comer forming has been quantified, defining the material strength distributions for both press braked and cold rolled sections. In addition, geometric profiles of 31 complete section lengths have been measured and over 800 residual strain readings performed. Since production routes also influence the geometric imperfections and residual stress distributions, they must be quantified to accurately predict structural behaviour. Simple models have been proposed to predict global and local imperfections and membrane and bending residual stresses in the three types of sections. Based on available test data, the proposed 0.2% proof stress distribution for press braked sections offers, on average, cross section resistances 1.4 times those predicted using the minimum 0.2% proof stress. The 0.2% proof stress distribution proposed for cold rolled sections provides cross section compression resistances, column buckling resistances and inplane bending resistances, on average, 2.1, 1.5 and 1.9 times respectively the values obtained using the minimum specified material strength. This research therefore identifies large increases in efficiency for stainless steel structural design which, combined with low maintenance requirements greatly increases the competitiveness of specifying stainless steel structures.Open Acces

Opioid Overdose Deaths in Vermont: Effectiveness of Buprenorphine Provider Density on Mortality Rates

Background Since 2017, there has been an increase in the frequency of mortality related to opioids in Vermont. Buprenorphine is a great alternative to traditional opioids because of its efficacy in treating opioid use disorder (OUD), however, it is underutilized by providers due to needing a specific waiver to prescribe it. This project looks at two different angles: is the number of Buprenorphine providers associated with the number opioid related deaths per county?; and does a rural setting in Vermont affect mortality rates due to a possible lack of Buprenorphine providers? Methods The incidence of overdose deaths per county to the number of buprenorphine providers per county were compared, as listed on the Vermont Department of Health website. Tukey HSD and Bonferroni statistical tests were run to measure a linear association between deaths per county and city town code (CTC). Grand Isle County was excluded from the analysis due to no deaths. Results Counties with medium provider densities had higher numbers of overdose deaths compared to counties with higher and lower provider densities. Some limitations in the study included the lack of diversity and the inability to synchronize the Vermont mortality data registry from 2017-2019 to the date buprenorphine providers received their x-waiver. Conclusion Further research is needed to investigate if there needs to be a reevaluation of the hub and spoke program as well as the impact of other factors, such as age and cities, have any effect on the opioid related death rates in Vermont

The 300m Eiffel Tower: the role of a structural principle

The Eiffel Tower has an iconic curved silhouette which was declared by the Tower’s designer, Gustave Eiffel, to have been determined by the pattern of wind loads acting on the Tower, using a structural principle. Adherence to this principle removed the need for cross-bracing to achieve stability, increasing the structure’s efficiency. When proposed, nothing equalling the Tower’s 300m height had ever been built and there was concern over whether wind loads at this height could be resisted, as well as the visual impact of the Tower. The principle was used to address both concerns, portraying the unusual profile as a technical necessity, rather than an aesthetic choice. However, cross-bracing has been used in the Tower’s top two-thirds, so the role of the principle in the Tower’s design isn’t completely clear. The analysis presented here demonstrates a lack of adherence to the principle in the initial proposals, a good adherence later on, but the final design shows a fundamental deviation from its use. Eiffel’s proclaimed use of the structural principle for reasons of structural efficiency can therefore be seen as a justification of the feasibility and aesthetics of the proposal, masking the uncertainties inherent in designing the tallest Tower at that time.</div

Effect of Crosslinking Agent Concentration on the Properties of Unmedicated Hydrogels

Novel polyethylene oxide (PEO) hydrogel films were synthesized via UV crosslinking with varying concentrations of pentaerythritol tetra-acrylate (PETRA) as crosslinking agent. The aim was to study the effects of the crosslinking agent on the material properties of hydrogel films intended for dermatological applications. Fabricated film samples were characterized using swelling studies, scanning electron microscopy, tensile testing and rheometry. Films showed rapid swelling and high elasticity. The increase of PETRA concentration resulted in significant increase in the gel fraction and crosslinking density (ρc), while causing a significant decrease in the equilibrium water content (EWC), average molecular weight between crosslinks (M¯c), and mesh size (ζ) of films. From the scanning electron microscopy, cross-linked PEO hydrogel network appeared as cross-linked mesh-like structure with interconnected micropores. Rheological studies showed PEO films required a minimum of 2.5% w/w PETRA to form stable viscoelastic solid gels. Preliminary studies concluded that a minimum of 2.5% w/w PETRA is required to yield films with desirable properties for skin application

Evaluating Ecosystem Services for the Expansion of Irrigation on Agricultural Land

Managing water resources requires consideration of both environmental and socio-economic benefits to effectively balance the benefits and costs. This includes identifying ecosystem services (ES) of concern and how to evaluate the project or proposed changes effect on these ES. The purpose of this effort is to describe methods to evaluate ecosystem services to provide expanded irrigation to existing agricultural lands in Alabama and the potential application to other areas. A case study has been undertaken on the Middle Alabama watershed in central Alabama and methods have been developed and applied to evaluate ES in terms of how irrigated versus rainfed fields will affect sediment retention, fertilizer usage and the effect of the subsequent discharges of sediment and nitrogen from fertilizer on water quality. The results of case studies in the Middle Alabama watershed indicate positive ES benefits from sustainable agricultural practices and the irrigation of agricultural lands versus rainfed fields. We anticipate these methods will be applicable to other watersheds outside the southeast region too

Evaluating Ecosystem Services for the Expansion of Irrigation on Agricultural Land

Managing water resources requires consideration of both environmental and socio-economic benefits to effectively balance the benefits and costs. This includes identifying ecosystem services (ES) of concern and how to evaluate the project or proposed changes effect on these ES. The purpose of this effort is to describe methods to evaluate ecosystem services to provide expanded irrigation to existing agricultural lands in Alabama and the potential application to other areas. A case study has been undertaken on the Middle Alabama watershed in central Alabama and methods have been developed and applied to evaluate ES in terms of how irrigated versus rainfed fields will affect sediment retention, fertilizer usage and the effect of the subsequent discharges of sediment and nitrogen from fertilizer on water quality. The results of case studies in the Middle Alabama watershed indicate positive ES benefits from sustainable agricultural practices and the irrigation of agricultural lands versus rainfed fields. We anticipate these methods will be applicable to other watersheds outside the southeast region too