<p>In the application of cold formed steel structural members, holes are usually cut in the webs of sections for passing pipes or conduits. The Canadian standard for the design of cold formed steel sections does not provide sufficient design information for theses conditions. However, the American Iron and Steel Institute has recently provided design guidelines for sections with circular perforations based on limited available experimental data.</p> <p>The purpose of this study is to determine the effect of size and shape of openings on the axial load behaviour of cold formed sections having different flat width-to-thickness ratios of webs.</p> <p>A total of fifty five stub column tests were performed to provide design guidelines for stiffened plates with openings. Cold formed lipped channel steel sections were selected for the tests. Circular, square or slotted holes were cut in the centres of webs. The diameter, or width of the openings, varied from 0 to 0.6 times the flat width of the web. The tests were performed under axial compression and centering of the specimen was done with the help of strain gauges. Load versis axial shortening and out-of-plane deflections curves are plotted. Experimental buckling loads of the sections are obtained using the strain reversal method. Ultimate loads of the stub columns are calculated using the effective width approach given in North American codes. An empirical relationship was derived from the experimental data for the effect of square of circular openings in the web on the strength of cold formed sections.</p> <p>It was found that the buckling load of a section decreases with respect to the buckling load of an unperforated section when size (diameter or width) of the opening is 20% of the flat width of the web but increases as the size of the opening is increased to 60%. The ultimate strength of sections with circular and square openings changes insignificantly when the size of the openings is 20% of the flat width of web. However, it drops to about 87% when the opening size is increased to 60%.</p> <p>The shape of the opening influences the degree of reduction in strength. The shapes in increasing order of influence are circular, square and slotted openings. The maximum drop in compressive strength, about 14%, was for the section with a slotted opening, of width of about 48% of the web flat width. It also shows the importance of both the longitudinal and transverse dimensions of the opening. The design guidelines provided by the American Iron and Steel Institute (1986) are conservative. The equation proposed herein accurately predicts the effect of square or circular perforations on the strength of the cold formed steel sections.</p> / Master of Engineering (ME)

Two anaerobic/aerobic sequencing batch reactors (SBRs) were used to evaluate enhanced biological phosphorus removal (EBPR). The first SBR, designated the Glucose SBR, was run for a period of four months. It received a synthetic wastewater plus glucose as a supplemental carbon source. The second SBR, the Isovaleric SBR, was run for three months. During the first month, isovaleric acid was its supplemental carbon source while for the remaining time period, no supplemental carbon source was added to the feed. Steady-state data from the SBR receiving isovalerate yielded the highest phosphorus (P) removals observed during the study, with a mixed liquor volatile suspended solid (MLVSS) P content of 7.2%. The next highest removals were observed when prefermented glucose was received, which yielded a MLVSS P content of 6.4%. The lowest removals were observed when no supplemental carbon source was added to the SBR influent, with at 4.4% MLVSS P content. Batch experiments were also conducted to quantify the effect of EBPR of glucose and the volatile fatty acids (VFAs) acetic acid, propionic acid, valeric acid, and isovaleric acid. Compounds giving the largest anaerobic P release ultimately yielded the lowest effluent P concentrations. At 0.80 mmoles/l, isovaleric acid resulted in anaerobic P released 9.5 mg/l greater than an equal amount of glucose or propionic acid, but ultimately gave effluent P values roughly 4 mg/l lower than either. Ratios of aerobic P uptake/anaerobic P release were found to be roughly equal for all the VFAs when the VFAs were compared on a molar basis. Propionic acid had aerobic P uptake/anaerobic P release ratios similar to the other VFAs. It also behaved the same as all the other VFAs with respect to the effect of concentrations added to the batch experiment; however, the magnitude of its removal was significantly lower than all the other substrates. Glucose, on the other hand, behaved differently from all the VFAs. Glucose aerobic P uptake/anaerobic P release ratios varied with concentration, which was not the case for the others substrates. Also, glucose P net removals decreased at concentrations higher than 0.60 mmoles/l. Glucose also resulted in net P removals roughly 2mg/l higher than propionic acid, but ultimately gave lower net P removal than isovaleric, valeric and acetic acids.

Laboratory and field studies were conducted to characterize phosphorus in bottom sediments for retention/detention ponds. The laboratory studies, including batch and column experiments, were conducted to assess possible removal processes. Sediment core samples were collected from detention ponds receiving urban runoff. These cores were analyzed for phosphorus at different layers including accumulated top sediments and the lower parent soil beneath it at a depth of 1, 3, 5, 10 and greater than 10 cm. The phosphorus accumulation rate was found to decline with calculated overflow rates from an average storm. Also attenuation of phosphorus with sediment depth followed an exponential decline. Batch experiments showed a higher adsorption capacity to remove phosphorus for top accumulated sediments than the lower parent soil, which is consistent with data from field studies showing greater phosphorus in the sediments. Phosphorus adsorption can be described by the Freundlich and Linear isotherms. Mass transfer rates varied with phosphorus concentration and contact time. A generalized model was developed to predict phosphorus removal in column studies.

This research addresses emissions of hexavalent chromium mist from hard chromium electroplating operations. Most of these emissions are typically captured by a ventilation stack and directed to a pollution control device; those which escape capture are called fugitive emissions. Releases of toxic materials such as hexavalent chromium must be reported annually to the Environmental Protection Agency (EPA) under provisions of the Superfund Amendments and Reauthorization Act (SARA) Title III of 1986 via the Toxic Release Inventory (TRI), Form R. The objectives were: (1) to provide estimates of fugitive hexavalent chromium emissions for the completion of Form R; and (2) to develop a predictive model for stack and fugitive emissions versus process and ventilation parameters. The database for stack emissions included published results from EPA studies. Fugitive release data were generated by field characterization at two operating facilities. Supplemental data for stack releases were also obtained during this field activity. The fugitive releases were documented to represent a small portion of the total atmospheric discharge; in most instances, the fugitive releases were less than the detection capability of the sampling/analytical protocols. Stack releases were successfully correlated with a measure of production activity (ampere-hours), production capacity (mass of chromium in the process bath), tank dimensions (plating bath surface area), and ventilation efficiency (ventilation slot area). This effort was supported by the EPA in the form of a cooperative agreement with the American Electroplaters and Surface Finishers Society (AESF).

The objectives of this research were to quantify formaldehyde consumption due to plating and parasitic reactions and determine the magnitude and distribution of formaldehyde losses from the electroless copper plating process. Plating and rinse bath samples obtained from three electroless copper plating operations were analyzed for formaldehyde and copper in order to develop a mass balance analysis about the plating bath for periods of active production and no production. Fugitive air and stack releases of formaldehyde were estimated using emission factors developed from air sampling at the three facilities. It was determined that approximately 90% of the formaldehyde added to the plating process was consumed by some type of chemical reaction. The remaining 10% of formaldehyde represents losses from the plating operation. For the facilities with a waste plating solution stream, atmospheric losses accounted for approximately 25% of the total losses. The mass of fugitive air formaldehyde measured approximately 2.8 times that escaping through the stack. Dragout accounted for approximately 2.3% of the losses with the remaining going to the waste stream. For the facility without a plating solution waste stream, formaldehyde losses were distributed 59% to atmospheric releases and 41% to the rinse tank. Fugitive and stack releases were approximately the same at 29% of the formaldehyde losses. Formaldehyde consumption due to parasitic reactions for periods of active plating and no plating were determined for two facilities. The rate of parasitic consumption during periods of production was found to be approximately 3 times greater than that for no production. The rate of parasitic consumption was observed to increase with increasing bath temperature.

No description available.

No description available.

No description available.

No description available.

No description available.