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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.)

This paper investigated the seismic retrofitting of an existing cable-stayed bridge through the use of a seismic isolation system. The bridge is situated in a high seismic zone. During the Saguenay earthquake 1988, one of the anchorage plates of the bridge supports failed. Herein, several configurations of seismic isolation system were considered to identify an appropriate solution for the seismic retrofitting of the bridge in both the longitudinal and transverse directions. A three-dimensional model of the bridge was created, and its seismic behavior studied through nonlinear dynamic time-history analysis. The comparative performance study among the five retrofitting configurations showed that the partial seismic isolation of the bridge led to an enhancement of the seismic response of the bridge in one direction only. However, the overall seismic response of the cable-stayed bridge substantially improved in the longitudinal and transverse directions in cases where the isolation systems were utilized between the supports and the deck-tower connection of the bridge., Competing Interests: The authors have declared that no competing interests exist.

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.)

Conventional design and evaluation procedures usually classify steel through-truss bridges as single-load-path structures; however, their historic performance has demonstrated considerable structural resiliency. This paper presents a study of the Grand River Bridge, a Pratt through-truss bridge in Cayuga, Ontario, Canada, that systematically investigates the load paths not conventionally assumed in design and evaluation. The bridge with individual truss members removed was analyzed using nonlinear finite-element analyses to investigate the alternative load paths and associated critical members and responses. A system reliability analysis was conducted to evaluate the failure probabilities of the bridge accounting for the member resistance uncertainties. The bridge was found to be sufficient to carry its nominal dead load, even for the worst case of removal of an end post. The end bottom chord and hanger vertical were found to be the critical tension chord and web member, respectively. If multiple alternative load paths exist, the variability of the system collapse load is much less than that of the critical member resistance. [ABSTRACT FROM AUTHOR]

The deterioration attributable to corrosion of concrete structures reinforced with unbonded, posttensioned tendons is a costly problem. Recent research has shown composite materials such as fiber-reinforced polymers (FRP) to be suitable alternatives to steel because they provide similar strength without susceptibility to electrochemical corrosion. Carbon-FRP (CFRP) in particular has great promise for prestressed applications because it shows resistance to corrosion in environments that might be encountered in concrete and experiences less relaxation than steel. This paper outlines the testing and implementation of a posttensioned system that uses CFRP tendons to replace corroded, unbonded posttensioned steel tendons. This system was then implemented in a parking garage in downtown Toronto. To the writers' knowledge, this is the first example of an unbonded, posttensioned tendon replacement using FRP tendons. The system used split-wedge anchors designed specifically for CFRP tendons. The dead end was anchored by directly bonding the tendon to the concrete slab. The CFRP tendon was successfully inserted in the opening created by the removal of the corroded tendon and stressed. Although the system was shown to be feasible, the current anchorage configuration results in load losses of up to 60% during the transfer. Changing the orientation of the anchor was found to reduce the load loss to an acceptable range of 1-9%. [ABSTRACT FROM AUTHOR]

Research into the use of fiber-reinforced polymers (FRPs) in structures at the Royal Military College of Canada (RMC) during the past two decades has largely focused on two important military engineering goals-mobility and survivability. FRP research in the area of mobility has included the strengthening and repair of reinforced concrete beams and slabs and the development of portable lightweight bridges suitable for most wheeled and tracked vehicles. With respect to survivability, a particular interest is in the use of FRPs to enhance the blast resistance of structural columns and beams. Such research may be equally pertinent to improving the blast resistance of a broad range of critical domestic infrastructure worldwide, given both the increasing concerns about terrorist acts and the desire as well to improve resistance to accidental explosion. This paper will report on the experimental work of two of the most recent FRP research projects carried out at the RMC in support of military objectives-the development of a lightweight portable glass FRP bridge and the use of FRP to strengthen reinforced concrete structural columns against blast. A full-sized FRP box beam was constructed and tested in the laboratory and 28 half-scale reinforced concrete columns, some strengthened with either steel reinforced polymer (SRP) or with FRP, were tested in the field under blast load. From this research, it can be seen that FRP as a structural material offers significant advantages to military forces working in conflict zones, whether for traditional strengthening of damaged or understrength structures, lightweight portable bridge options, or as a means of strengthening structures against blast effects. [ABSTRACT FROM AUTHOR]

In performance-based seismic design of a structure, the inelastic deformation demand of structural members or system is the primary input, whereas in conventional design procedure the input is the equivalent static loads to represent seismic effects. The National Building Code of Canada (NBCC) requires that for irregular and buildings higher than 60 m, dynamic analysis must be conducted to calculate seismic design forces and deflection, while for other cases, equivalent static loads can be used for the design. In this paper, the performance of a 20-story steel moment resisting steel frame building, designed for western part of Canada, has been presented. Simulated and actual (scaled) ground motion records are used to evaluate the dynamic response. While NBCC does not provide any performance-based design method, various techniques for displacement-based design have been explored here in the context of the 20-story building. A wide range of variation amongst these methods in terms of their application and results was found. Amongst these methods the direct displacement-based design method seems to be more suitable for carrying out the performance-based design of a building. Copyright © 2009 John Wiley & Sons, Ltd. [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.)

The consumption of non-renewable resources and the creation of wastes have been identifi ed as among the key issues that our society must address in order not to prejudice the opportunities of future generations. Yet the way we design and construct our buildings leads to huge volumes of waste being generated as well as the use of large amounts of materials, the extraction of which leads to considerable environmental damage. So, how can we design buildings in a way that creates closed loop materials systems that minimize waste generation and primary resourse use? The objective of this paper is to review work carried out at Ryerson University in Canada funded by NRCan and CISC to identify ways in which construction can set up reuse loops for steel components so that waste and the demand for primary steel are reduced. In particular, the design and construction issues related to the use of salvaged steel components will be reviewed, through a series of case studies to draw out lessons and conclusions about the implications of component reuse in construction. The case studies are of projects that reuse steel components from old buildings into new buildings. They suggest that opportunities for steel reuse are signifi cant but the industry needs to establish appropriate structures and cyclical systems and methods to ensure that components can be easily reclaimed from old buildings for reuse. Furthermore, certain ingrained industry design processes need to be overcome for reuse of steel (and other components) to become more acceptable. [ABSTRACT FROM AUTHOR]

This article is a case study from the Hebron Offshore Oil Platform located in Atlantic Canada focusing on fire-resistant medium-voltage enclosures that were supplied for the seawater lift pumps and fire water pumps. The purpose of this article is to show where fire-resistant enclosures may be utilized and to detail the testing involved in achieving fire resistance with the enclosures for the Hebron Platform. [ABSTRACT FROM AUTHOR]

This paper introduces and assesses the seismic and collapse behavior of a new lateral load-resisting system referred to as steel Moment-Resisting Knee Braced Frame (MKF). A design method following the Performance Based Plastic Design (PBPD) procedure is proposed to analyze the structure and size the structural members. A prototype frame part of an office building located in Vancouver, British Columbia, Canada is then selected to demonstrate the design method and evaluate the performance of the proposed system. The prototype MKF is also designed using the conventional elastic approach in accordance with the National Building Code (NBC) of Canada. The seismic performance and collapse response of the proposed system are examined using the nonlinear static analysis, nonlinear response history analysis (NLRHA) and incremental dynamic analysis (IDA) performed on the prototype five-story MKF under potential sources of seismicity in the west coast of Canada including shallow crustal, subduction interface and subduction intraslab events. Fragility curves are finally developed using results of the IDA to obtain the collapse probability of the system. The results of the analyses are compared to those obtained from a steel Moment-Resisting Frame (MRF) counterpart designed in accordance with the PBPD and elastic approaches. Findings of the study show that the proposed steel MKF can efficiently satisfy the code-specified story drift limit and manifest the yielding mechanism assumed in design. The MKF designed according to the PBPD approach offers the lightest structure among all frames studied and yields a collapse probability lower than that of the MKF designed as per the elastic design method. The proposed system can be used in seismic design of steel multi-story buildings as an alternative to conventional steel MRFs. • A new steel lateral load-resisting system referred to as Moment-Resisting Knee Braced Frame (MKF) is introduced. • A Performance-Based Plastic Design method is proposed to design the system. • The seismic performance of proposed MKFs are evaluated and compared to conventional steel MRFs. • Compared to steel MRFs, the proposed MKF offers similar lateral stiffness and collapse behavior with reduced steel tonnage. • MKF can be considered as a viable alternative to conventional steel MRFs in multi-story buildings. [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.)

Modern building codes allow engineers to use reduced seismic loads in design provided that the seismic load resisting system (SLRS) of the structure is adequately designed and detailed to withstand strong ground shaking through ductile inelastic response. This approach has been adopted by the North American model codes, which typically include special provisions to achieve satisfactory inelastic seismic performance. Single-story buildings often incorporate a steel roof deck diaphragm that is relied on to transfer lateral loads to the vertical bracing bents. The vertical braces are usually selected as the energy dissipating fuse element, while the diaphragm and other elements in the SLRS should be designed such that their capacity exceeds the nominal resistance of the braces. Steel bracing members designed for compression inherently possess significant reserve strength when loaded in tension, which means that large brace tension loads must be considered in the design of the surrounding protected structural components. Capacity design seismic provisions have led to the need for much thicker roof deck panels and more closely spaced diaphragm connection patterns compared with past practice En Canada. This paper describes the current U.S. seismic design approach and provides examples as it is applied to single-story buildings and their diaphragms. An overview of the related aspects of an ongoing research project on the flexibility and ductility of the roof diaphragm in low-rise steel buildings is also included. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the seismic performance of moment-resisting frame steel buildings with multiple underground stories resting on shallow foundations. A parametric study that involved evaluating the nonlinear seismic response of five, ten and fifteen story moment-resisting frame steel buildings resting on flexible ground surface, and buildings having one, three and five underground stories was performed. The buildings were assumed to be founded on shallow foundations. Two site conditions were considered: soil class C and soil class E, corresponding to firm and soft soil deposits, respectively. Vancouver seismic hazard has been considered for this study. Synthetic earthquake records compatible with Vancouver uniform hazard spectrum (UHS), as specified by the National Building Code of Canada (NBCC) 2005, have been used as input motion. It was found that soil–structure interaction (SSI) can greatly affect the seismic performance of buildings in terms of the seismic storey shear and moment demand, and the deformations of their structural components. Although most building codes postulate that SSI effects generally decrease the force demand on buildings, but increase the deformation demand, it was found that, for some of the cases considered, SSI effects increased both the force and deformation demand on the buildings. The SSI effects generally depend on the stiffness of the foundation and the number of underground stories. SSI effects are significant for soft soil conditions and negligible for stiff soil conditions. It was also found that SSI effects are significant for buildings resting on flexible ground surface with no underground stories, and gradually decrease with the increase of the number of underground stories. [Copyright &y& Elsevier]

Although the steel industry has brought economic benefits to many countries, it also has non-negligible impacts on the environment. To understand how steel production impacts are shared among trading countries, it is necessary to conduct a large scale research from environmental and economic perspectives. This study applies the life cycle assessment method (LCA) to analyze 12 major iron-mining and steel-making countries, calculate a "unit GDP impact intensity" and finally raise an issue of "pollution allocation" among actors in international trade. Results firstly indicate that normalized ecotoxicity impacts over the entire production chain are among the most crucial consequences of iron and steel production, even higher than the non-negligeble impacts from carbon emissions. Secondly, performance indicators indicating the relation between environmental impacts and economic activities can be calculated as Total Normalized Impacts/GDP, an inverse measure of environmental versus economic efficiency. South Africa has the highest unit GDP impact intensity (4.35E-4 TNI/US $) in iron mining, while Canada has the largest intensity in steel manufacturing (5.81E-3 TNI/US $). Thirdly, countries that largely benefit from importing "pollution-free" materials, should share a proportional responsibility for the environmental pollution caused by iron&steel processing activities occurring in their trade partner countries: this is especially true for China and US, which are major iron ore/steel importing economies. Finally, this paper proposes policy implications at local, national and international levels, from a perspective of global sustainable development. • Environmental impacts of iron mining and steel production are assessed by using LCA. • Toxicity is the most important problem. • South Africa and Canada have the highest UNI among iron/steel producing countries, respectively.. • Importing countries should take responsibility of generated impacts. [ABSTRACT FROM AUTHOR]

Coiled tubing corrosion was investigated for 16 field water samples (S5 to S20) from a Canadian shale gas field. Weight loss corrosion rates of carbon steel beads incubated with these field water samples averaged 0.2 mm/yr, but injection water sample S19 had 1.25±0.07 mm/yr. S19 had a most probable number of zero acid-producing bacteria and incubation of S19 with carbon steel beads or coupons did not lead to big changes in microbial community composition. In contrast other field water samples had most probable numbers of APB of 102/mL to 107/mL and incubation of these field water samples with carbon steel beads or coupons often gave large changes in microbial community composition. HPLC analysis indicated that all field water samples had elevated concentrations of bromide (average 1.6 mM), which may be derived from bronopol, which was used as a biocide. S19 had the highest bromide concentration (4.2 mM) and was the only water sample with a high concentration of active bronopol (13.8 mM, 2760 ppm). Corrosion rates increased linearly with bronopol concentration, as determined by weight loss of carbon steel beads, for experiments with S19, with filtered S19 and with bronopol dissolved in defined medium. This indicated that the high corrosion rate found for S19 was due to its high bronopol concentration. The corrosion rate of coiled tubing coupons also increased linearly with bronopol concentration as determined by electrochemical methods. Profilometry measurements also showed formation of multiple pits on the surface of coiled tubing coupon with an average pit depth of 60 μm after 1 week of incubation with 1 mM bronopol. At the recommended dosage of 100 ppm the corrosiveness of bronopol towards carbon steel beads was modest (0.011 mm/yr). Higher concentrations, resulting if biocide is added repeatedly as commonly done in shale gas operations, are more corrosive and should be avoided. Overdosing may be avoided by assaying the presence of residual biocide by HPLC, rather than by assaying the presence of residual surviving bacteria. [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.)

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.)

This study evaluates the seismic response of an advanced hybrid steel‐timber structure using a nonlinear static and dynamic analyses. A three‐story prototype building located in Vancouver, BC, Canada was designed first. The gravity load resisting system (GLRS) consists of cross‐laminated timber (CLT) floor slabs, glulam beams, and glulam columns. The lateral load resisting system (LLRS) includes a chevron‐type steel Concentrically Braced Frame. The numerical model of the structure was then developed in the OpenSees program. Nonlinear hysteresis response of steel braces and timber joints were explicitly simulated. The results of the analysis revealed that the hybrid structure possess an acceptable lateral stiffness while providing sufficient ductility to dissipate seismic energy. No unsatisfactory response was observed in the timber system. [ABSTRACT FROM AUTHOR]