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Post-tensioned cross-laminated timber (PT-CLT) walls have been demonstrated to be a low-damage seismic force-resisting system (SFRS) due to their self-centering capability. However, there is still a need to examine the seismic performance of such SFRS in high-seismic risk zones. This study evaluates the seismic performance of 6-, 9-, and 12-storey PT-CLT shear wall buildings in Vancouver, Canada, equipped with buckling-restrained axial fuses. The prototype buildings were designed using the displacement-based design method, and the assessment considered the most recent seismic hazard model provided in the 2020 National Building Code of Canada. To conduct nonlinear response history analysis (NLRHA) and incremental dynamic analysis (IDA), numerical models were developed in OpenSeesPy and calibrated based on component- and system-level experimental tests. The NLRHA and IDA results demonstrate that all the studied buildings have adequate collapse margin ratios, with less than a 10% chance of collapsing at the maximum considered earthquakes. [ABSTRACT FROM AUTHOR]

Corrugated web plate girders (CWPGs) have grown in popularity in Canada in recent years because of their economic efficiency. Although research on the flexural performance of such members has increased in recent years, there are still additional advancements that can be made in their design, particularly in the calculation of lateral torsional buckling resistance. However, no research has been presented in Canada on this subject, and very minimal research has been published on CWPGs with sinusoidal corrugated webs. The purpose of this study was to examine the lateral torsional buckling strength of CWPGs with sinusoidal corrugated web profiles through experimental analysis of CWPGs that are currently being used in Canada. Nine simply supported specimens were loaded and failed in lateral torsional buckling (LTB). The nine specimens were chosen according to size in order to observe variations in LTB strength based on web thickness, web depth, and variations in identical beams. All beams tested recorded strengths far greater than conventional design strength, confirming the conservative nature of the current design procedure. As web thickness increased, a trend of ultimate capacity increasing was observed. The depth of the webs had no significant effect on LTB strength apart from what was gained by increasing the depth of the flanges. Based on the results, an equivalent web thickness equation is proposed for the purpose of calculating a more precise LTB resistance. A numerical analysis was run on a wide range of beam sizes and compared with the physical testing results. It was determined that the proposed equation effectively captured the physical testing results among more than just the tested beams. However, future work should further examine the reliability of the proposed equation by testing more specimens and/or using the finite-element method. [ABSTRACT FROM AUTHOR]

This paper evaluates the overstrength, ductility, and response modification factors for low to mid-rise buckling restrained braced frames (BRBFs) designed as per the 2010 National Building Code of Canada. In addition to nonlinear static pushover analyses, dynamic time history analyses are performed to assess the seismic performance of four-, six-, and eight-story BRBFs. Different bracing configurations, including chevron (inverted-V) and split-X braces, are considered for the building frames with varied frame span lengths of 6 m and 8 m. The results confirm that the prescribed design values for overstrength and ductility factors provide reasonable estimations of the lower bound for these factors. The response modification factor obtained in this study ranged from 4.8 to 6 for different frames. The results also indicate that the response modification factor decreases with the increase of story height and span length. Moreover, bracing configurations may slightly affect the response modification factor for BRBFs. [ABSTRACT FROM AUTHOR]

The shear buckling of web plates and lateral–torsional buckling are among the major failure modes of plate girders. The importance of the lateral–torsional buckling capacity of plate girders was further evidenced when several plate girders of a bridge in Edmonton, Alberta, Canada failed in 2015, because insufficient bracing led to the lateral buckling of the plate girders. In this study, we focus on the optimisation of the cross-sections of plate girders using a well-known and extremely efficient meta-heuristic optimisation algorithm called the harmony search algorithm. The objective of this optimisation is to design the cross-sections of the plate girders with the minimum area that satisfies requirements, such as the lateral–torsional buckling load and ultimate shear stress. The base geometry, material properties, applied load and boundary conditions were taken from an experimental study and optimised. It was revealed that the same amount of load-carrying capacity demonstrated by this model can be achieved with a cross-sectional area 16% smaller than that of the original specimen. Furthermore, the slenderness of the web plate was found to have a decisive effect on the cost-efficiency of the plate girder design. [ABSTRACT FROM AUTHOR]

Orogenic curvature is a ubiquitous feature of mountain belts, and the plate tectonic and geodynamic setting responsible for the development of curved orogens is a subject of debate. In order to distinguish between different models of orocline formation it is necessary to tightly constrain the absolute timing of oroclinal development. However, determining the absolute (isotopic) timing of oroclinal bending is challenging. The most direct method available to constrain the time interval during which an orocline formed is to obtain absolute age constraints on fabrics generated within syn-orocline strike–slip shear zones that accommodated rotations around a vertical axis during the development of crustal or lithospheric scale orogenic curvature. Here we present a data set of 40 Ar/ 39 Ar ages obtained from five shear-zones, some of which display curved traces parallel to the Cantabrian Orocline structural grain in NW Iberia and are interpreted to have been generated coevally to it. The 40 Ar/ 39 Ar ages were obtained by laser-rastering induced step-heating on single muscovite crystals that grew synkinematically during shearing. All five samples yielded ages that cluster tightly at 308 ± 3 Ma providing direct evidence for the age of oroclinal bending. This age is consistent with the age constraints obtained from paleomagnetic and structural data that place the onset of oroclinal bending in Moscovian times. Our 40 Ar/ 39 Ar age determinations therefore provide a reliable absolute constraint on the age of buckling of the Variscan orogen around a vertical axis and provide further evidence that oroclinal bending is unrelated to Variscan convergence/collision or the subsequent extensional collapse of the mountain belt. [ABSTRACT FROM AUTHOR]

The structural steel design specification in Canada, CSA S16-14, uses the same equations for the design of rolled and welded shape beams for lateral torsional buckling (LTB). A recent study has shown that the current design equations might overestimate the capacity of welded wide flange (WWF) beams. This paper evaluates the performance of the current design equations in providing LTB capacities of welded I-shape beams (WWF beams). An extensive finite element (FE) analysis is performed for simply supported WWF beams subjected to constant moment. In total, 256 FE models are analyzed and it is observed that both CSA and AISC overestimate the LTB capacity of welded I-shape beams by as much as 37%, particularly when residual stress measured at Lehigh University is used in the analysis. Also, the Eurocode is found to be conservative and the proposed equation by MacPhedran and Grondin in 2011 provides better predictions of LTB strengths of WWF shapes than the current CSA approach. [ABSTRACT FROM AUTHOR]

Objective: To determine the effectiveness of a macular buckle procedure without vitrectomy for the treatment of symptomatic myopic macular schisis., Design: Retrospective case series., Participants and Methods: All patients who underwent surgery with placement of an NPB macular buckle (AJL Ophthalmic, Miñano, Álava, Spain) without vitrectomy for symptomatic myopic macular schisis were included. Visual acuity and anatomical outcomes based on optical coherence tomography (OCT) were reviewed., Results: Eight consecutive eyes from 7 patients were included. Six of the 7 patients were female and the mean age was 59 ± 6 years (range, 49-66 years). The mean follow-up duration was 11 ± 7 months (range, 3-23 months). Mean preoperative axial length was 29.54 ± 1.28 mm (range, 27.88-31.96 mm). Mean preoperative best-corrected visual acuity (BCVA) was 0.71 ± 0.29 logMAR (Snellen equivalent 20/103); mean postoperative BCVA was 0.46 ± 0.44 (Snellen equivalent 20/58; p = 0.19) and 87.5% of patients maintained or improved vision. Pre- and postoperative OCT images are included and discussed within. Preoperative ellipsoid zone status and postoperative central macular buckle indentation appear to be important in visual outcomes. Two patients required a buckle repositioning for persistent schisis. One patient developed a macular hole postoperatively that resolved with subsequent vitrectomy. There were no other complications., Conclusions: The macular buckle is an effective and promising therapeutic option for myopic macular schisis., (Copyright © 2019 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Extensive research has shown that properly detailed and closely spaced transverse reinforcement in reinforced concrete columns can ensure ductile behavior during earthquakes. However, in regions of high seismicity, detailing requirements can result in heavily congested sections; the use of self-consolidating concrete (SCC) can facilitate construction in these situations. Although extensive research exists on the axial load behavior of traditional concrete columns, only limited research exists on the behavior of columns constructed with SCC. Research over the past two decades has also shown that use of steel fiber-reinforced concrete (SFRC) can improve the strength and ductility of columns by delaying cover spalling and improving core confinement. Recent research has also shown that the combined use of SCC and steel fibers can ease problems associated with the workability of traditional fiber-reinforced concrete. This paper presents the results from an experimental program that was conducted to study the axial behavior of reinforced concrete columns constructed with SCC and SFRC. Full-scale columns having rectangular cross sections were tested under pure axial compressive loading. The columns were detailed with varying amounts of transverse reinforcement in accordance with the requirements of the Canadian Standards Association. The results confirm that increasing confinement with closely spaced transverse reinforcement in rectangular SCC columns results in improvements in behavior and ductility. In addition, the results demonstrate that the use of SFRC in rectangular columns results in improvements in performance and ductility. [ABSTRACT FROM AUTHOR]

This article describes a shake table test program that was conducted to investigate the seismic behavior of a half‐scale two‐story gravity‐controlled rocking braced steel frame building. In this system, braced frame columns are designed to uplift from the foundation under severe earthquakes to reduce the seismic force demands on the frame members. Self‐centering capacity is solely provided by the gravity loads carried by the rocking frame. Energy dissipative devices are added at the base of the braced frame columns to control drifts. The system can be used for new structures as well as the retrofit of seismically deficient structures. In the test program, the specimen represented a gravity‐controlled rocking frame that had been proposed for seismic retrofit in a previous study. The test structure was subjected to ground motions expected for two site classes in two seismically active regions in Canada. Three different energy dissipative devices located at the rocking interface were studied: friction, friction spring dampers, and steel bars yielding in tension and elastically buckling in compression. The focus of the tests was on peak axial loads in the columns and additional moments and shears in the beams resulting from column impact upon rocking. Axial loads in the braces and columns from higher mode response were also examined. The tests revealed significant increases in beam forces due to column impacts. Large axial forces due to the second vibration mode response were measured in the second story braces. A numerical model is proposed to accurately predict the measured force demands. [ABSTRACT FROM AUTHOR]

The seismic performance of 15 continuous four-span bridges with different arrangements of column heights and diameters and designed using the 2006 Canadian Highway Bridge Design Code provisions were studied using incremental dynamic analysis (IDA). The seismic risk associated with exceeding different damage states in the columns, including yielding, cover spalling, bar buckling, and structural collapse (i.e., dynamic instability) was predicted. Some simplified equations were derived for Montreal, Quebec, Canada, to estimate the mean annual probability of exceeding different damage states in the columns using the IDA results. The results indicated that the probabilities of exceeding different damage states were reasonably low. [ABSTRACT FROM AUTHOR]

The intensity and frequency of extreme rainfall events have increased in North America and the world due to climate change. Extreme rainfall events, characterized by a heavy volume of rainfall in a short duration, have triggered the onset of urban flash floods. Over the years, flash flooding has been reported in different cities in Canada, which resulted in many losses. Subsequently, different green roofing systems have been adopted to control urban stormwater runoff as part of Nature-Based Solutions (NBS) to mitigate urban flood and build a flood-resilient city. Currently, no specific widely recognized standard or code is dedicated to determining the hydrological performance of green roofs as a whole system. Moreover, there are no test protocols to regulate the design of green roof systems in the market. A comprehensive literature review examines existing research methods adopted to evaluate influencing parameters affecting the hydrological performance of NBS-CR. The results indicate several limitations in experimental and field investigations. Consequently, to address these limitations, it is essential to formulate a multi-functional work plan to develop a standardized test method that can become a common platform for the roofing industry to test and quantify the hydrological performance of their systems. [ABSTRACT FROM AUTHOR]

The prohibitive costs of small-scale solar photovoltaic (PV) racks decrease PV adoption velocity. To overcome these costs challenges, an open hardware design method is used to develop two novel variable tilt racking designs. These are the first stilt-mounted racking designs that allow for the manual change of the tilt angle from zero to 90 degrees by varying the length of cables. The racks are designed using the calculated dead, wind, and snow loads for Canada as a conservative design for most of the rest of the world. Structural capacities of the wooden members are then ascertained and the resisting bending moment, shear force, tensile force, and compressive force is calculated for them. A structural and truss analysis is performed to ensure that the racking design withstands the applicable forces. Moreover, the implications of changing the tilt angle on the wooden members/cables used to build the system are also determined. The systems offer significant economic savings ranging from one third to two thirds of the capital expenses of the commercially available alternatives. In addition, the racking designs are easy-to-build and require minimal manufacturing operations, which increases their accessibility. The stilt-mounted designs can be employed for agrivoltaic settings while allowing farm workers shaded, ergonomic access to perform planting, weeding, and harvesting. [ABSTRACT FROM AUTHOR]

A commissioning test of the deep-burial simulator at Queen's University, Canada, was conducted on a 3.05-m-diameter steel-reinforced polyethylene pipe to evaluate the behavior and design of this pipe class under deep burial. The diameter change measurements indicated that friction on the side walls was mitigated ensuring that the surface load was transferred to the pipe. Measurements of the displacement and rotation of the surface loading plates and strain in the steel reinforcing strips combined with visual observations after exhumation indicated that the pipe failed due to yielding of the steel reinforcing ribs. The surface pressure that the pipe was able to withstand exceeded the maximum burial depth specified by the manufacturer. Comparisons are also made between the experimental thrust forces at the springline and estimates from two design codes and a finite-element estimate; all were similar, with the rate of thrust increase with overburden pressure from the computer analysis approximately 8% larger than the measurement. Thus, the experimental results confirm that use of finite-element and code-equation analyses to design this pipe class for deep-burial conditions appear to be appropriate. [ABSTRACT FROM AUTHOR]

• Combined out-of-plane bending and compression is an inevitable loading condition for CLT walls. • The experimental program consisted of 36 CLT panel specimens. • The damage was caused by the local buckling near the mid-height of the outer layer on the compression side. • Signs of shear failure of cross layers were evident almost simultaneously with the outer layer failure. • The interaction equations specified in the Canadian design standard are appropriate for the CLT panels under small load eccentricities. Combined out-of-plane bending and compression is an inevitable loading condition for cross-laminated timber (CLT) walls due to the out of plumbness, initial panel curvature and load eccentricity. Because of the weaker cross layers, the mechanical performance and failure mode of the CLT panels under such loading significantly differ from those of the other wood members, such as sawn timber and glulam. This experimental study focuses on investigating the behavior of CLT panels under the stated loading scenario. The experimental program consisted of 36 specimens, including 12 five-layer CLT panels provided by two Canadian manufacturers, as well as 12 three-layer and 12 five-layer CLT panels provided by a Chinese manufacturer. All the specimens were tested in Canada and China, respectively, using the same test setup. It was found that in the majority of the specimens, the damage was caused by the local buckling near the mid-height of the outer layer on the concave compression side at about 45%–60% of the ultimate failure load and 25%–35% of the ultimate deflection. The dominant failure mode was characterized as the crushing yield of the outer layer on the concave side (fibers in compression) near the mid-height after the local buckling progressed. Signs of shear failure of cross layers were evident almost simultaneously with the outer layer failure. Hence, although the dominant failure mode was likely triggered by the fracture in the cross layers due to rolling shear, the load-carrying capacity of the CLT panels under the combined out-of-plane bending and compression is governed by the compression failure of the longitudinal outer layers. It was found that a cross-layered panel can maintain its integrity before failure. It was also noted that the interaction equations specified in the Canadian design standard are appropriate for the CLT panels under small load eccentricity, while for panels that have large load eccentricity, the appropriateness of the interaction equation is questionable. Based on the test results obtained, the validity of the interaction equation for the prediction of the load-carrying capacity of CLT columns, specified in the CSA O86-19, is confirmed for cases in which P f / P r > 0.5 and M f / M r < 0.3. For the cases of P f / P r < 0.5 and M f / M r > 0.3 , modification of the equation is needed. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop spatiotemporal whole-stem wood quality prediction models for a suite of end-product-based fibre attribute determinates for jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Aiton): specifically, for wood density (Wd), microfibril angle (Ma), modulus of elasticity (Me), fibre coarseness (Co), tracheid wall thickness (Wt), tracheid radial diameter (Dr), tracheid tangential diameter (Dt), and specific surface area (Sa). Procedurally, these attributes were determined for each annual ring within pith-to-bark xylem sequences extracted from 610 jack pine and 223 red pine cross-sectional disks positioned throughout the main stem of 61 jack pine and 54 red pine sample trees growing within even-aged monospecific stands in central Canada. Deploying a block cross-validation-like approach in order to reduce serial data dependency and enable predictive performance assessments, species-specific calibration and validation data subsets consisting of cumulative moving average values were systematically generated from the 27,820 jack pine and 11,291 red pine attribute-specific annual ring values. Graphical, correlation, regression and validation analyses were used to specify, parameterize and assess the predictive performance of tertiary-level (ring-disk-tree) hierarchical mixed-effects whole-stem equations for each attribute by species. As a result, the jack pine equations explained 46, 66, 74, 63, 59, 72, 42 and 48% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. The red pine equations explained slightly higher levels of variation except for Me: 50, 71, 31, 83, 72, 78, 56 and 71% of the variation in Wd, Ma, Me, Co, Wt, Dr, Dt and Sa, respectively. Graphical assessments and statistical metrics related to attribute and species-specific residual error patterns and goodness-of-fit, lack-of-fit and predictive error metrics, revealed an absence of systematic bias, misspecification or aberrant predictive performance. Consequently, the resultant parameterized models were acknowledged as acceptable functional descriptors of the intrinsic spatiotemporal cumulative developmental patterns of the studied end-product fibre attribute determinates, for these two pine species. Although predicted development patterns were similar between the species with the greatest degree of nonlinearity occurring before a cambial age of approximately 30 years, irrespective of attribute, jack pine exhibited a greater degree of nonlinearity in the Wd and Dt developmental trajectories, whereas red pine exhibited a greater degree of nonlinearity in the Ma, Me, Co, Wt, Dr and Sa developmental trajectories. Potential biomechanical linkages underlying the observed attribute distribution patterns, as well as the potential utility of the models in forest management, are also discussed. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives. Seat-belt wearing rates in the North reflect workers in the oil industry, necessitating sociocultural descriptions on the issue. The objective of this study was to describe how the social context influences oil workers' views of risk and seat-belt wearing behaviour in northern Alberta. Study Design. The study design was qualitative research. Focus groups were held with oil workers in three northern Alberta locations. Methods. Forty-five oil industry workers participated in 3 focus groups held in a different northern Alberta location, each consisting of 15 participants. Focus group discourse was centred on a series of questions that were clustered around the following themes: (1) propensity to take risks; (2) work patterns and workplace routines; (3) driving history and patterns; (4) self-disclosed seat-belt wearing behaviour; and (5) social relationships. Results. Northern oil workers believe that taking safety risks is an essential characteristic of who they are and where they work. Employers demand consecutive number of hours on the job and offer attractive incentives for working overtime that encourages risk-taking. Risk-taking also appears in driving where workers take numerous risks to get home after they have worked 12-hour shifts for 14 consecutive days. Most are situational seat-belt wearers, buckling up in inclement weather, at the presence of numerous logging trucks and the threat of drunk and/or fatigued drivers. Without prompting, northern oil workers consider fatigued driving as the most dangerous driving risk they experience in the north. Nearly every respondent has experienced fatigued driving after completing his last work shift in a 14-day rotation. Conclusions. Seat-belt wearing initiatives for oil workers during off-work driving should be led by the oil industries. For example, they could support and encourage the police to increase their enforcement, lobby the government for higher penalties, punish their workers who are caught not wearing seat belts and collaborate with local communities to develop programs that will increase awareness of seat-belt wearing. Because workers described fatigued driving as the key risk in the North, oil industries should become engaged in interventions, with seat-belt wearing as a vital component of fatigued driving. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Buried medium-density polyethylene (MDPE) pipes are widely used for gas distribution systems in Canada and worldwide. When exposed to geotechnical hazards such as ground movements, these pipes can experience excessive distresses, leading to leaking or failure. This research investigates the effects of ground movement near a tee connection of MDPE gas distribution pipes. If the ground movement is parallel to a branch, the branch pipe experiences an axial force, and the main pipe experiences bending deformation/strains. The axial forces and the wall strains were investigated in this study using full-scale laboratory tests. Test results showed that the axial force on the branch and strains on the main pipe depend on the burial depth, backfill soil density, and the pipe diameter due to the effects on the shearing resistance of the soil. The soil shearing resistance was less for shallow buried pipes, resulting in a lower axial force in the branch but higher bending strain in the main pipe. The axial pullout resistance of the main pipe also contributed to the wall strains of this laterally loaded pipe at large displacements. The conventional beam-on-elastic foundation solution reasonably estimated the pipe wall strains within the linear range of deformations. Nonlinear analyses, including lateral and axial soil springs, are recommended to capture the nonlinear responses at large displacements. [ABSTRACT FROM AUTHOR]

While damping devices can provide supplemental damping to mitigate building vibration due to wind or earthquake effects, integrating them into the design is more complex. For example, the Canadian code does not provide building designs with inline friction dampers. The objective of this present article was to study the overstrength, ductility, and response modification factors of concrete frame buildings with inline friction dampers in the Canadian context. For that purpose, a set of four-, eight-, and fourteen-story ductile concrete frames with inline seismic friction dampers, designed based on the 2015 National Building Code of Canada (NBCC), was considered. The analyses included pushover analysis in determining seismic characteristics and dynamic response history analysis using twenty-five ground motion records to assess the seismic performance of the buildings equipped with inline seismic friction dampers. The methodology considered diagonal braces, including different 6 m and 8 m span lengths. The discussion covers the prescribed design values for overstrength, ductility, and response modification factors, as well as the performance assessment of the buildings. The results revealed that increasing the height of the structure and reducing the span length increases the response modification factors. [ABSTRACT FROM AUTHOR]

The seismic resilience of structures can be quantified through rigorous seismic assessment. Because no detailed guideline is available for nonlinear modelling parameters and the corresponding acceptance criteria for the seismic evaluation and upgrading of steel structures in Canada, the structural commentary of the National Building Code of Canada suggests using ASCE 41, which has been adopted as a standard for seismic evaluation and retrofit of buildings in the United States (U.S.). However, because the steel design standards in Canada and the U.S. are different, their applicability to steel structures in Canada needs to be investigated. To this end, this paper critically reviews the nonlinear modelling parameters and acceptance criteria, and then recommends whether these values need to be revised or are adopted as is for the seismic evaluation and upgrading of steel structures in Canada. A numerical example of a steel moment-resisting frame is presented to demonstrate the recommended parameters being used for seismic evaluation. [ABSTRACT FROM AUTHOR]

Host–parasite coevolution may lead to patterns of local adaptation in either the host or parasite. For parasites with complex multi‐host life cycles, this coevolution may be more challenging as they must adapt to multiple geographically varying hosts. The tapeworm Schistocephalus solidus exhibits some local adaptation to its second intermediate host, threespine stickleback, to which the parasite is strictly specialized. However, the tapeworm's adaptation to its first intermediate host (any of a number of copepod species) is not documented. We investigated if there was local adaptation and host specify in the tapeworm Schistocephalus solidus to its copepod first intermediate hosts. We exposed copepods from five lakes in Vancouver Island (BC, Canada) to local (i.e. same lake) and foreign tapeworms in a reciprocal exposure experiment. Results indicate that the tapeworm is not locally adapted to the copepods. Instead, we observed moderate‐effect host specificity, infection rates being higher in certain copepod species than in others. Infection rates also varied among cestode populations. These results show that although S. solidus infects multiple copepod genera, they are not equally competent hosts. Differences in S. solidus epidemiology among lakes is likely to be driven more by this partial specialization, than by local adaptation to first intermediate hosts. [ABSTRACT FROM AUTHOR]

The constant fluctuation of thermal loads on steel members, especially during construction, causes non-uniform distributions of temperatures, resulting in possible constructional and structural defects leading to unfavorable thermally induced responses and potential safety risks. The Canadian Highway Bridge Design Code (CHBDC) provides one thermal gradient variation profile without accounting for the differences in the geometrical parameters of the steel members and the variations in the climate regions of Canada. Therefore, in this study, three-dimensional finite element (FE) thermal simulations were conducted to investigate the maximum effective temperatures and positive vertical thermal gradients for different Canadian climate regions. Parametric studies were performed to conduct the FE thermal analysis using the thermal model validated in ANSYS. The comprehensive study results showed that Canada could be divided into two main zones for vertical thermal gradient calculations, meaning that one stationary thermal gradient profile cannot be applicable to all climate regions of Canada, as recommended by the CHBDC. Based on the FE thermal analysis results, empirical formulas as a function of the significant parameters were proposed to predict the maximum effective temperature and thermal gradient variations of the steel I-girder. The predicted maximum effective temperature and thermal gradient variation values were found to be highly correlated with the FE values with coefficients of determination R2 of approximately 0.97 and 0.98, respectively. [ABSTRACT FROM AUTHOR]

The National Research Council Canada (NRC) is currently developing seismic evaluation and upgrading guidelines for existing buildings in Canada. The seismic evaluation guidelines consist of three tiers of seismic evaluation procedures, that is, Tier 1 Quick Evaluation, Tier 2 Deficiency-Based Evaluation, and Tier 3 Detailed Evaluation. This paper presents the Tier 1 Quick Evaluation procedure, which aims to update the initial quick evaluation procedure in the existing seismic evaluation guidelines developed by the NRC in early 1990s. The proposed procedure covers seismic assessment of both structural and non-structural elements, and requires the review of construction documents, on-site inspection, and calculations. A set of checklists are contained to uncover potential key seismic deficiencies of the building under evaluation. The checklists are in the form of evaluation statements that relate to potential seismic deficiencies in the structural systems and non-structural components. The proposed procedure is demonstrated by conducting the seismic evaluation of an existing building that is part of a pilot study. [ABSTRACT FROM AUTHOR]

The desire of using sustainable materials has reignited the interest in timber-based construction. Researchers and practitioners are developing novel timber-based structural solutions. Cross-laminated timber (CLT)-coupled wall is a recently proposed system for potential use in mid- and high-rise timber construction. The National Building Code of Canada, however, does not include this system and, consequently, the seismic force modification factors are not available. This study evaluated the ductility-related force modification factor (Rd) using the FEMA P-695 procedure. Nine archetype buildings were designed considering different design parameters: building storey height, CLT wall configuration, and coupling ratios. Using 30 ground motion records (bi-directional), rigorously selected for seismicity of Vancouver, BC, Canada, incremental dynamic analyses were performed. Collapse margin ratios were calculated to assess the adequacy of the trial Rd factors. Using an over-strength factor of 1.5, Rd = 4 is found to be acceptable for this system. [ABSTRACT FROM AUTHOR]

Our understanding of the present‐day state and evolution of the Canadian and Alaskan mantle is hindered by a lack of absolute P‐wavespeed constraints that provide complementary sensitivity to composition in conjunction with existing S‐wavespeed models. Consequently, cratonic modification, orogenic history of western North America and complexities within the Alaskan Proto‐Pacific subduction system remain enigmatic. One challenge concerns the difficulties in extracting absolute arrival‐time measurements from often‐noisy data recorded by temporary seismograph networks required to fill gaps in continental and global databases. Using the Absolute Arrival‐time Recovery Method (AARM), we extract >180,000 new absolute arrival‐time residuals from seismograph stations across Canada and Alaska and combine these data with USArray and global arrival‐time data from the contiguous US and Alaska. We develop a new absolute P‐wavespeed tomographic model, CAP22, spanning North America that significantly improves resolution in Canada and Alaska over previous models. Slow wavespeeds below the Canadian Cordillera sharply abut fast wavespeeds of the continental interior at the Rocky Mountain Trench in southwest Canada. Slow wavespeeds below the Mackenzie Mountains continue farther inland in northwest Canada, indicating Proterozoic‐Archean metasomatism of the Slave craton. Inherited tectonic lineaments colocated with this north‐south wavespeed boundary suggest that both the crust and mantle may control Cordilleran orogenic processes. In Alaska, fast upper mantle wavespeeds below the Wrangell Volcanic Field favor a conventional subduction related mechanism for volcanism. Finally, seismic evidence for the subducted Kula and Yukon slabs indicate tectonic reconstructions of western North America may require revision. Plain Language Summary: Our understanding of the plate tectonic history of North America is incomplete. Outstanding questions include: 1. Have ancient parts of the North American plate been modified over time or remained unchanged since assembly? 2. What processes produced the differing shape of the western Canadian Cordilleran Mountains along their length? 3. Can we image the old plate remnants that were recycled back into the mantle at subduction zones to better understand how North America was formed? We use earthquakes that produce P‐waves, recorded at distant receivers, to seismically image the mantle below North America, including new data from Canada and Alaska for the first time. Slower‐than‐expected seismic wavespeeds that continue from the west coast inland toward north‐central Canada suggest the ancient Slave Craton has been modified by chemical processes ≥500 million years ago. An abrupt seismic wavespeed boundary perpendicular to the Canadian Cordilleran Mountains suggests their shape may be controlled by pre‐existing zones of weakness in the crust and mantle. Fragments of old tectonic plates, stuck in the mantle below western North America and Alaska, suggest our understanding of the final stages of assembly of modern North America requires revision. Key Points: North American absolute P‐wavespeed tomographic model incorporating dense seismic networks in Canada and AlaskaImaged fast wavespeed subducted remnants suggest revision of Alaskan and proto Pacific subduction models is necessarySlow wavespeed structures imply Slave Craton metasomatic modification and tectonic inheritance during Cordilleran orogenesis [ABSTRACT FROM AUTHOR]

The Arctic is the fastest warming biome on the planet, and environmental changes are having striking effects on freshwater ecosystems that may impact the regional carbon cycle. The metabolic state of Arctic lakes is often considered net heterotrophic, due to an assumed supply of allochthonous organic matter that supports ecosystem respiration and carbon mineralization in excess of rates of primary production. However, lake metabolic patterns vary according to regional climatic characteristics, hydrological connectivity, organic matter sources and intrinsic lake properties, and the metabolism of most Arctic lakes is unknown. We sampled 35 waterbodies along a connectivity gradient from headwater to downstream lakes, on southern Victoria Island, Nunavut, in an area characterized by low precipitation, organic-poor soils, and high evaporation rates. We evaluated whether lakes were net autotrophic or heterotrophic during the open water period using an oxygen isotopic mass balance approach. Most of the waterbodies were autotrophic and sites of net organic matter production or close to metabolic equilibrium. Autotrophy was associated with higher benthic primary production, as compared to its pelagic counterpart, due to the high irradiance reaching the bottom and efficient internal carbon and nutrient cycling. Highly connected midstream and downstream lakes showed efficient organic matter cycling, as evidenced by the strong coupling between gross primary production (GPP) and ecosystem respiration, while decoupling was observed in some headwater lakes with significantly higher GPP. The shallow nature of lakes in the flat, arid region of southern Victoria Island supports net autotrophy in most lakes during the open water season. Ongoing climate changes that lengthen the ice-free irradiance period and increase rates of nutrient evapoconcentration may further promote net autotrophy, with uncertain long-term effects for lake functioning., (© 2024 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

The design provisions for internal glass fiber-reinforced polymer (GFRP) reinforced concrete (RC) columns have been recently under consideration by design committees in Canada and around the world due to new advancements in understanding the behavior of GFRP-RC columns. The slenderness limit is a critical design parameter differentiating between the first- and second-order analyses of GFRP-RC columns. The existing slenderness limits in design standards were calibrated using deterministic approaches. In this study, a novel reliability-based approach was utilized to quantify the reliability index associated with the slenderness limit to calibrate and propose optimized reliability-based slenderness limits for CSA S806 and CSA S6, for the first time. The method takes the advantage of artificial intelligence and incorporates a comprehensive experimental database. [ABSTRACT FROM AUTHOR]

The 2020 National Building Code of Canada (NBCC) seismic hazard model (SHM) marks a comprehensive update over its predecessor (NBCC 2015). For different regions in Canada, this will have an impact on the design of new buildings and performance assessment of existing ones. In the present study, a recently developed hybrid building system with reinforced concrete (RC) moment-resisting frames and cross-laminated timber (CLT) infills is assessed for its seismic performance against the latest SHM. The six-story RC-CLT hybrid system, designed using the direct displacement-based method, is located in Vancouver, Canada. Along with very high seismicity, southwestern British Columbia is characterized by complex seismotectonics, consisting of subduction, shallow crustal, and in-slab faulting mechanisms. A hazard-consistent set of 40 ground motion pairs is selected from the PEER and KiK-net databases, and used to estimate the building's seismic performance. The effects of using steel slit dampers (associated with large hysteresis loops) and flag-shaped energy dissipators (associated with the recentering capability) are investigated. The results indicate that the hybrid system has good seismic performance with a probability of collapse of 2–3% at the 2475-year return period shaking intensity. The hybrid building with steel slit dampers exhibits a collapse margin ratio of 2.8, which increases to 3.5–3.6 when flag-shaped dissipators are used. The flag-shaped dissipators are found to significantly reduce the residual drift of the hybrid building. Additionally, the seismic performance of the hybrid building equipped with flag-shaped dissipators is found to improve marginally when the recentering ratio is increased. [ABSTRACT FROM AUTHOR]

This paper presents the results of a benchmarking study on face support practice in seismically active mines in Australia and Canada. The choice of ground support strategies is based on the anticipated strainburst hazard as well as corporate, legislative, and operational requirements. Although mines appear to employ similar face support standards, using friction rock stabilizers and mesh, the details and the resulting coverage vary from site to site. The variations in design and coverage result in significantly different residual risks. The case is made for documenting strainburst events at the mining face and using this information to formally assess the effectiveness of implemented face support practice at the various mine sites. [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]

Coupled shear walls (CSW) are an efficient lateral load-resisting system. Their seismic performance depends primarily on their coupling beams (CBs) ability to provide adequate stiffness and strength. However, many existing buildings with CSW resisting system were designed and constructed according to old codes and standards with insufficient requirements for seismic design. These systems feature unsatisfactory behaviour and prematurely collapse in case of major earthquake events. Therefore, their seismic retrofit is urgently needed. The main objectives of this study are, i) evaluate and compare the seismic performance of CSWs designed to old and new codes; ii) highlight the deficiencies of CSWs designed to old codes; iii) investigate a retrofit method using externally bonded (EB) carbon fibre reinforced polymer (CFRP) composites to enhance the seismic response of deficient CSWs. To that end, a 20-story CSW is considered with different design details including one according to old National Building Code of Canada (NBCC) before the 1970s and the other one designed consistent with the new NBCC 2015 and the Canadian Standard Association, CSA A23.3–14, for Eastern seismic Canadian zone. The nonlinear analyses of CSWs under earthquake records are conducted in two steps. At first, the nonlinear time-history analyses of two types of CSWs are carried out using RUAUMOKO program and the deficiencies of old-designed CSW are identified through the comparison of obtained results. In the second step, the old design CSW is retrofitted using CFRP sheets and reanalysed to investigate the benefits of the retrofit technique in mitigating the shortcomings. The results indicate that CFRP retrofitting is an efficient method to enhance the seismic performance of deficient old CSWs in terms of story displacement, inter-story drift, CBs rotation, and ductility demand. [ABSTRACT FROM AUTHOR]

Lack of robustness is a major barrier to foster a sustainable cyanobacterial biotechnology. Use of cyanobacterial consortium increases biodiversity, which provides functional redundancy and prevents invading species from disrupting the production ecosystem. Here we characterized a cyanobacterial consortium enriched from microbial mats of alkaline soda lakes in BC, Canada, at high pH and alkalinity. This consortium has been grown in open laboratory culture for 4 years without crashes. Using shotgun metagenomic sequencing, 29 heterotrophic metagenome-assembled-genomes (MAGs) were retrieved and were assigned to Bacteroidota, Alphaproteobacteria , Gammaproteobacteria , Verrucomicrobiota , Patescibacteria , Planctomycetota , and Archaea. In combination with metaproteomics, the overall stability of the consortium was determined under different cultivation conditions. Genome information from each heterotrophic population was investigated for six ecological niches created by cyanobacterial metabolism and one niche for phototrophy. Genome-resolved metaproteomics with stable isotope probing using 13C-bicarbonate (protein/SIP) showed tight coupling of carbon transfer from cyanobacteria to the heterotrophic populations, specially Wenzhouxiangella. The community structure was compared to a previously described consortium of a closely related cyanobacteria, which indicated that the results may be generalized. Productivity losses associated with heterotrophic metabolism were relatively small compared to other losses during photosynthesis. [ABSTRACT FROM AUTHOR]

Abstract: Deformation structures differing in style and orientation within a given terrane are often attributed to distinct tectono-metamorphic events. However, mechanical heterogeneities may locally cause strain perturbations that can have a profound effect on the geometry of such structures. Here we document highly variable orientations of planar structures, metre- to kilometre-scale folds and shortening directions inferred from brittle fault analysis within the synclinal and layered Sudbury Igneous Complex (SIC) and its Huronian host rocks. NW–SE shortening during Palaeoproterozoic deformation led to the formation of planar structures in the host rocks that are parallel to the NE–SW striking contact of the southern SIC. During deformation, local contact-parallel shortening became more important than regional NW–SE shortening and generated contact-orthogonal planar mineral fabrics and folds. Local contact-parallel shortening is attributed to the shape change of the southern SIC from a convex outward to a concave inward curvi-planar geometry. Contact-parallel shortening accounts for the formation of a previously unidentified kilometre-scale buckle fold in the SIC and respective axial–planar mineral fabrics in Huronian host rocks. This buckle fold shares similar structural characteristics with known higher-order buckle folds of the eastern SIC. We suggest that non-cylindrical buckling and associated mineral fabric development accommodated the shape change of the SIC. This resulted in mutually perpendicular fabric orientations, which are compatible with overall NW–SE shortening. The original shape of the SIC seems to have had a profound influence particularly on the geometry of metamorphic foliations. Our structural analysis supports earlier structural studies advocating that highly discordant planar strain fabrics can be generated by local strain perturbations near igneous sheets under uniform regional shortening. [Copyright &y& Elsevier]

This paper presents an analytical study of the seismic behavior of two different types of industrial buildings; a regular mill-type crane-supporting steel structure and an irregular heavy industrial building housing a vertical mechanical process. For both structures, the seismic response is examined through elastic time-history dynamic analyses in order to validate the predictions from the equivalent static force procedure and the response spectrum analysis method prescribed in current building codes. The analyses also serve to assess the inelastic demand in crane-supporting structure. For the crane-supporting structure, analyses are performed for sites in Montreal and Vancouver in Canada and in Seattle in the United States. The results show that the median horizontal displacement and acceleration from the time-history analyses are generally well predicted by the code analysis methods. Inelastic response in these buildings is likely to develop in the form of buckling of the lower column segment, a failure mode that exhibits limited ductility. For the tall irregular building, the analyses are performed for the Montreal site only. The results show the equivalent static method provides fair displacements estimate, but may lead to unconservative predictions of column and brace forces. Response spectrum analysis method, as prescribed in design codes, appears to provide appropriate prediction of the seismic response of such highly irregular structures. For both building types, a good prediction from response spectrum and time-history analysis methods is possible only when a sufficient number of modes are used. [ABSTRACT FROM AUTHOR]