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Prince Rupert, Canada

Erochko J.,University of Toronto | Christopoulos C.,University of Toronto | Tremblay R.,Geological and Mining Engineering | Choi H.,Sungkyunkwan University
Journal of Structural Engineering | Year: 2011

A recent study has shown that residual drifts after earthquakes that are greater than 0.5% in buildings may represent a complete loss of the structure from an economic perspective. To study the comparative residual drift response of special moment-resisting frames (SMRFs) and buckling-restrained braced (BRB) frames, buildings between 2 and 12 stories in height are designed according to ASCE 7-05 and investigated numerically. This investigation includes pushover analyses as well as two-dimensional nonlinear time-history analyses for two ground motion hazard levels. The two systems show similar peak drifts and drift concentration factors. The BRB frames experience larger residual drifts than the SMRFs; however, the scatter in the residual drift results is large. Expressions are proposed to estimate the residual drifts of these systems as a function of the expected peak drifts, the initial recoverable elastic drift, and the drift concentration factor of each system. When subjected to a second identical earthquake, both framing systems experienced larger-than-expected drifts when an initial drift greater than 0.5% was present. © 2011 American Society of Civil Engineers.

Moreau R.,McGill University | Rogers C.,McGill University | Tremblay R.,Geological and Mining Engineering
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2013

Steel concentrically braced frames (CBFs) are popular seismic-force-resisting systems for low-to medium-rise buildings in Canada. Hollow structural section (HSS) members are commonly used for the lateral braces of these CBFs. HSS braces are often connected to the bracing-bent frames by using a slotted tube-to-gusset plate or knife-plate connection. This connection creates the potential under seismic loading for fracture of the tube through the net section, which can be further affected by shear lag. Shear lag factors calculated according to CSA S16 are quite penalizing, and can lead to expensive connection reinforcements when seismic capacity design methods must be applied. Furthermore, it is known that the yield stress of steel increases with strain rate; this places additional demand on the connection since it must be designed for the expected yield strength of the brace under seismic loading. However, strain-rate effects are typically ignored in design. This paper describes the testing of four HSS brace connections for HSS 152 × 152 × 9.5 and HSS 203 × 203 × 13.0 members under monotonic tensile loading. For each tube size, one brace was tested under a static rate, while the other brace was tested using a strain rate consistent with that which would occur during a design level earthquake. This paper reports on the applicability of existing design shear lag factors for square HSS sections, as well as the effect of strain rate on HSS brace connection behaviour.

Boudreault J.-P.,Ecole de Technologie Superieure of Montreal | Dube J.-S.,Ecole de Technologie Superieure of Montreal | Marcotte D.,Geological and Mining Engineering
Geoderma | Year: 2016

The remediation of contaminated sites is recognized as a means towards the sustainable development of an expanding urban space on the global scale. However, it is often hindered by financial and environmental risks caused by undetected contamination or unreliable site characterization. Uncertainty in site characterization studies is suspected to be a cause of this problem. Therefore, there is a need for formally defining and quantifying the uncertainty linked to estimates of the spatial distribution of contamination and the volume of contaminated soils at polluted sites. The objective of this study was to develop a geostatistical procedure for the 3-D analysis of a multi-element contamination in order to: 1) optimize the location and the number of sampling stations during a complementary sampling campaign, 2) estimate the volume of contaminated soil for a given data set and 3) quantify the uncertainty of this estimate. This procedure is innovative because it takes into account, by a transformation in pollution indices, the presence of a multi-element contamination and applies to a set of 3-D data. Furthermore, this procedure offers a formal framework that adapts the decisional bounds to the study site to help the decision-maker. The proposed procedure was applied to an urban site characterized by the presence of a strongly heterogeneous fill. From a subset initially constituted of 8 sampling stations, supplemental sampling stations were selected within a complementary data set and added one by one to the iterative geostatistical simulations. The completeness of the sampling plan was determined upon reaching stability in the relative differences of both global uncertainty and global variance between two successive steps of the optimization. According to the procedure presented, a sampling plan could be considered optimized and complete with 19 sampling stations for this study site (comparatively to 38 sampling stations for the total set obtained by systematic sampling). For 19 sampling stations, the global uncertainty was determined to be 20% (comparatively to 16% for the total set). © 2015 Elsevier B.V.

Tfaily R.,Geological and Mining Engineering | Papineau I.,Geological and Mining Engineering | Andrews R.C.,University of Toronto | Barbeau B.,Geological and Mining Engineering
Journal - American Water Works Association | Year: 2015

A quantitative microbial risk assessment model developed by Health Canada was applied at 17 water treatment plants (WTPs) located throughout Ontario and Quebec, Canada. Four source water characterization methods were compared that considered Escherichia coli, Giardia, and Cryptosporidium. In addition, three strategies to evaluate chemical disinfection performances were compared (median disinfectant exposure [CT50], regulatory disinfectant exposure [CT10], and continuous-stirred tank reactors in-series [N-CSTR, where N is the number of CSTRs in the series]). The N-CSTR approach provides more reliable risk estimates because it is less sensitive to high inactivation conditions (when compared with use of CT10 or CT50). Predicted risk estimates for the 17 WTPs revealed that only two did not comply with the 10â€"6 disability-adjusted life years (World Health Organization) and 10â€"4 risk of infection (US Environmental Protection Agency) reference levels because of the poor performance of direct filtration without coagulation. This publically available quantitative microbial risk assessment model could help WTP managers assess overall treatment performance via a systematic evaluation process. © 2015 American Water Works Association.

Papineau I.,Geological and Mining Engineering | Tufenkji N.,McGill University | Barbeau B.,Geological and Mining Engineering
Water Science and Technology: Water Supply | Year: 2013

Granular filtration remains a key barrier for Cryptosporidium removal in water treatment plants without UV irradiation. To assess the impact of clay particles in source water on Cryptosporidium removal efficiency by granular filtration, this study investigated the co-transport of Cryptosporidiumsized microspheres and kaolinite particles in sand columns. To investigate the influence of clay load on microsphere transport and deposition, varying influent kaolinite concentrations (0-106 particles/mL) and microsphere concentrations (102-106 microspheres/mL) were tested. The spatial distribution of retained microspheres was examined subsequent to experiments via filter coring. Results demonstrate that increasing the influent microsphere concentration impaired filter performance due to a blocking mechanism whereby previously retained particles repel incoming particles. In contrast, when the particulate load was dominated by kaolinite (for an equivalent particulate load), filter performance improved as a result of filter ripening whereby previously deposited particles act as additional collectors. Thus, microsphere-kaolinite interactions proved to be favorable although both particles possessed negative zeta potentials in the tested conditions. This study demonstrates that granular filter performance is vulnerable to peak events of microbial contamination. Conversely, Cryptosporidium-sized microsphere removal by granular filtration is enhanced in the presence of kaolinite in source water.© IWA Publishing 2013 Water Science and Technology: Water Supply.

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