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Visual inspection is a common approach for collecting data over time on transportation infrastructure. However, the evaluation method in visual inspections mainly depends on a subjective metric, as well as the experience of the individual performing the task. State-space models (SSMs) enable quantifying the uncertainty associated with the inspectors when modeling the degradation of bridges based on visual inspection data. The main limitation in the existing SSM is the assumption that each inspector is unbiased, due to the high number of inspectors, which makes the problem computationally demanding for optimization approaches and prohibitive for sampling-based Bayesian estimation methods. The contributions of this paper are to enable the estimation of the inspector bias and formulate a new analytical framework that allows the estimation of the inspectors' biases and variances using Bayesian updating. The performance of the analytical framework is verified using synthetic data where the true values are known, and validated using data from the network of bridges in Quebec province, Canada. The analyses have shown that the analytical framework has enabled reducing the computational time required for estimating the inspectors' uncertainty and is adequate for the estimation of the inspectors' uncertainty while maintaining a comparable performance to the gradient-based framework. [ABSTRACT FROM AUTHOR]

Tailings dams, which are storage structures for tailings, often are constructed using the tailings itself. A large number of tailings dam failures have been reported recently, especially due to static liquefaction, and can be attributed to a lack of knowledge of the geotechnical principles to be used and the lack of characterization of tailings as they continuously are produced and used as construction materials. Furthermore, the majority of past research work has been based on triaxial conditions even though it is believed that direct simple shear conditions may better represent the in situ condition of a tailings dam structure. This paper characterized the behavior of a tailings material from a copper tailings storage facility in Canada using the critical state soil mechanics framework using constant volume (undrained), drained, and constant shear drained shearing tests in direct simple shear space. The correlation between a modified state parameter (ψm) with instability state and the flow potential was investigated. Special attention was paid to the behavioral features of the material such as pore-water pressure generation, flow rule and dilatancy, phase transformation, characteristics state, and how they correlate with ψm. The differences in behavior from that of natural granular soils were highlighted. [ABSTRACT FROM AUTHOR]

Improving the operational effectiveness of hydropower systems is becoming more relevant considering the shift to renewable energy sources and the rising social, financial, and environmental costs associated with the construction of new hydropower facilities. This challenge is interdisciplinary as it involves technical, managerial, and institutional aspects. This paper focuses on a technical aspect, more specifically on the relationship between the quality of short-term ensemble streamflow forecasts and the energy produced by a hydropower system. A secondary objective is to measure the contribution of both the meteorological and structural uncertainties on the energy output. To achieve this, a numerical experiment comprising multiple sets of hydrologic ensemble forecasts of different quality and a suite of reservoir optimization models is developed for a case study in Canada (the hydropower system of the Gatineau River basin). These ensemble forecasts are processed by the short-term reservoir operation model in rolling-horizon mode over a planning period of 6 years. Each day, the short-term optimization model seeks to maximize the energy output over the 14-day forecast lead time considering the expected future value of the system derived from a midterm optimization model. The relationship between hydropower generation and common statistical scores characterizing the ensemble forecasts indicates that although there is a link between the quality of the forecasts and the energy production, it is not a one-to-one causal relationship. Our results also show that the diversity of hydrological models is beneficial to the production of energy, indicating that the diversity of model structures compensates the deficiencies of individuals models and adds value to the forecast. [ABSTRACT FROM AUTHOR]

This paper provides an outlook on the effects of climate change and the severity and frequency of extreme weather events on the performance of flexible pavements across North America. Now more than ever, the climate is changing at a rapid pace, which will alter long-term environmental loading parameters and extreme weather events. Such alterations will pose implications for the design, maintenance, and rehabilitation of flexible pavements, especially in terms of their serviceability, safety, and functionality. In northern Canada, roads are founded on various terrain types, including thaw-sensitive ice-rich permafrost underlying terrains. Such roads have experienced signs of embankment and pavement damage, which are usually induced by the degradation of the underlying permafrost due to climate change. Therefore, the development and implementation of new permafrost thaw mitigation techniques for vulnerable roads are essential and will be discussed in this paper. Resilient flexible roads should be designed to withstand the conditions that are likely to occur during their design life, taking into account the impact of the climate change on pavement performance in response to daily and seasonal changes in heat, precipitation, freeze–thaw cycles, and extreme weather events. [ABSTRACT FROM AUTHOR]

The lateral strength and stiffness requirements due to wind loads usually govern the design of tall buildings. The current building codes in the US, Canada, and Europe recognize the first significant yield point as an ultimate limit state. Consequently, the current design practices ignore the plastic capacity of structural systems in the nonlinear range, which could result in overdesigned buildings. Thus, the classical linear-elastic design arguments shall be reexamined with consideration of performance-based wind design (PBWD) approaches, innovative technologies, and materials. We are presenting two companion papers to demonstrate the benefits of considering the nonlinear capacity of structural systems in the design of wind-excited buildings. In this paper, Part I, we have postulated and then proved the capability of self-centering systems in controlling the possible damage accumulation in structural systems subjected to along-wind loads. Our arguments are based on an extensive parametric study through nonlinear time history analyses considering peak and residual ductility-demands, normalized hysteretic energy dissipation, and the rate of damage accumulation as performance indicators. Overall, the results of the parametric study revealed that self-centering systems could benefit the most from the ductility-based design due to their inherent recentering capability, higher energy dissipation, and lower sensitivity to wind duration. Consistent with the notion of PBWD, for self-centering systems, the companion Part II paper demonstrates the benefits of the ductility-based wind design in terms of economics and safety through structural reliability analysis. [ABSTRACT FROM AUTHOR]

This paper presents the results of load and resistance factor design (LRFD) calibration of the facing limit states for soil nail walls. The current AASHTO facing load model and a modified model together with the AASHTO facing resistance models for both permanent and temporary facing load cases are considered. The facing design includes flexure, punching shear, and headed-stud tensile limit states. The calibration of resistance factors captures uncertainty in the accuracy of the load and resistance models, uncertainties in the nominal load and resistance values at time of design, and bias dependencies between model bias and nominal values. Resistance factors are calibrated for a range of load factors and target reliability indexes. Example designs for facing limit states demonstrate the implementation of the calibrated resistance factors in a LRFD framework using the current AASHTO and modified load models for the permanent facing load case. The practical values of this study are calibrated load and resistance factors for facing limit states of soil nail walls that are of interest to code writers for future editions of LRFD codes in the United States and Canada. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of revised seismic hazard values in the National Building Code of Canada (NBCC 2015) on the design of reinforced-concrete (RC) shear wall buildings. Five buildings with different heights located in three cities in Canada are selected. Toronto, Montreal, and Vancouver are selected to represent low, medium, and high seismic hazard zones. The buildings are designed according to the NBCC 2010 and then checked against the updated design spectral accelerations of the NBCC 2015. The seismic demands are compared, and the need for retrofit of existing walls is evaluated. The analyses showed that the maximum interstory drift ratios increased specially for buildings in Vancouver. The shear force and bending moment demands increased for most buildings in Vancouver by up to 32% and 60%, respectively. A significant decline in the moment overstrength ratio was noticed for walls in Vancouver, which indicates that flexural strengthening might be mandatory for these walls. Moreover, the code changes had a great negative impact on the walls' ductility for buildings in Vancouver due to the higher deformations exhibited. Several retrofit techniques available in the literature were discussed to enhance the flexural strength and ductility of RC shear walls as remedies for the consequences of the updated seismic hazard in Canada. [ABSTRACT FROM AUTHOR]

The current method for estimating parallel-to-grain dowel bearing strength of cross-laminated timber (CLT) fasteners applied perpendicular to the face in the US adjusts the length of the fastener to account for the effect of cross-layers rather than modifying the dowel bearing strength. This method is counter to more-commonly used methods in Canada and Europe which adjust the dowel bearing strength of the CLT material and using the original length of the dowel. Currently, there are no experimental data supporting the use of an adjusted fastener length. This paper presented an alternative method for CLT dowel bearing strength assessment according to the US design code. The proposed method produced similar or slightly conservative dowel bearing strength values compared with the current US design method. Experimental results of dowel bearing strength were compared against the current design code, the proposed method, and European and Canadian codes. Standard test procedures were used to evaluate, stiffness, yield strength, 5% offset yield strength and ultimate strength. Greater mechanical properties were found for CLTs containing more parallel-to-grain layers, whereas lower mechanical properties were found for CLTs containing more perpendicular-to-grain layers. The current US dowel bearing strength method, the proposed method, and the European design code produced similar results, which were slightly conservative compared with the experimental values. The proposed dowel bearing strength equation is felt to be an improvement given the ease of use and similarity in form to other design formats. [ABSTRACT FROM AUTHOR]

The paper demonstrates load and resistance factor design (LRFD) calibration for tensile strength and pullout strength limit states for steel strip mechanically stabilized earth (MSE) walls using a reliability theory-based approach. The analyses adopt load models found in current North American LRFD specifications in combination with a coupled mechanical-corrosion model for the reinforcement tensile strength and pullout models found in design guidelines and in the research literature. Resistance factors for prescribed load factors and different load and resistance model combinations are compiled in tables. The limitations of the LRFD approach to generate resistance factors that are judged to be acceptable based on current practice are demonstrated. The challenges to generate consistent design outcomes with the same margin of safety expressed probabilistically are identified, and the link to reliability-based design is described. Example designs are provided to show the impact on steel reinforcement quantities and length when using different models in combination with proposed and current specified load and resistance factors. The calibration outcomes will be of value to code writers in Canada and the US for MSE wall design sections in the next editions of national geotechnical foundation LRFD codes. [ABSTRACT FROM AUTHOR]

Previous food-energy-water-environment (FEWE) nexus studies have primarily focused on technical aspects, such as data analysis and model development. However, to inform policy and the resulting management of resources in politically complex transboundary systems, nontechnical human factors in the FEWE nexus should also be considered. This paper explores the human dimension of the FEWE nexus in the Columbia River basin between the US and Canada. We hosted a workshop with regional government agencies to review and evaluate current policies and management of the institutional aspect of FEWE resources. We then surveyed residents from both the US and Canada, who share transboundary water resources in the region, to evaluate their awareness of the FEWE nexus and its related policies, representing the residential aspect. The outcomes of the workshop showed that (1) a consensus of common metrics for all sectors (food, energy, water, and environment) can provide a uniform basis for cross-sectoral comparison; (2) it is critical to have adaptive management and interagency coordination mechanisms; and (3) the support of local residents is key to successful policy implementation. The survey results suggested that residents understand a strong relationship between water and energy sustainability. Females and renters showed stronger support for policies related to FEWE sustainability. Combining knowledge from the workshop and survey will support the development of a more realistic modeling framework. [ABSTRACT FROM AUTHOR]

A lower shear strength and higher compressibility impose major challenges for construction on organic soils. Cementitious materials have been effectively used in the improvement of the engineering properties of mineral soils with low organic contents. However, limited studies have been devoted to the stabilization of the organic soils commonly encountered in forested regions in Canada. The present study investigated the effects of pulp mill fly ash (PFA) on the compressibility of a natural soil consisting of 26% organic matter. Fall-cone and oedometer tests were conducted on organic soil mixed with different PFA dosages (5%, 10%, 20%, 30%, 40%, and 50%), as well as on untreated soil samples. The mineralogical and microstructural aspects of PFA-treated organic soil were examined using scanning electron microscope and energy-dispersive X-ray spectroscopy techniques. The results suggest that when the organic soil was treated with PFA, its undrained shear strength and compressibility behavior were improved. Moreover, the potentially large settlement of organic soil can be reduced by the addition of PFA. The primary and secondary compression index (Cc and Cα, respectively) values decreased significantly when compared with the untreated organic soil, indicating that PFA stabilizers can effectively improve the creep behavior of organic soils. These findings indicate that the beneficial utilization of PFA for the stabilization of organic soils could be a practical step toward the environmentally sound management of this waste byproduct. [ABSTRACT FROM AUTHOR]