Newfield G.,Read Jones Christoffersen Ltd. |
Wang J.B.,Codes and Standards Structural Engineering
WCTE 2016 - World Conference on Timber Engineering | Year: 2016
With the introduction of 5 and 6-storey wood structures into the National Building Code of Canada 2015, it is important that guidance be provided to engineers to ensure that a reasonable design approach can be sought in the design of taller wood structures. The purpose of this technical paper is to compare various methods for calculating building deformations for wood-platform framed structures, which range from simply assuming each storey acts independent of the adjacent storey to a purely mechanics-based approach considering all 6 storeys acting as a continuous wall in order to compare the differences in drifts, stiffness, building period, base shear, and force distribution based on relative stiffness. General guidance is provided on which method to use.
Parker N.,Read Jones Christoffersen Ltd.
Proceedings, Annual Conference - Canadian Society for Civil Engineering | Year: 2012
This paper intends to compare four of the more common Green Building Rating Systems: Living Building Challenge (LBC) 2.0™, Leadership in Energy and Environmental Design (LEED®), Green Globes Canada™, and Building Research Environmental Assessment Method (BREEAM®) SD 5055. With the exception of BREEAM, UK based, the other three systems are based, or have an operational arm, in Canada. It was found that although there are many similarities between the systems, significant questions remain around the degree to which content and process differences between the systems influence environmental performance outcomes. In order to best answer these questions relating to differences between the various systems, the rating systems' requirements were compared across six broad categories: Site, Water, Energy, Health, Materials and Other. The results are further sub-divided into the LBC's imperatives, with the exception of areas where all of the other three systems overlapped and 'other' categories. In grouping the requirements under the broad scope of the LBC 2.0's imperatives, an objective comparison of was achieved. It was found the LBC is by far the most exhaustive system with the most stringent requirements. Conversely, Green Globes tends to be the least stringent of the three systems but also that of the lowest cost. LEED remains the system that tends to garner the most public attention in Canada and BREEAM was found to be the most technical of the four systems as well as the most detailed and involved.
Desalegne A.S.,AECOM Technology Corporation |
Lubell A.S.,Read Jones Christoffersen Ltd
ACI Structural Journal | Year: 2015
There is increasing interest in the use of high-performance reinforcing steel in concrete structures as a means to reduce the life-cycle costs of civil infrastructure. ASTM A1035 Grade 690 (100 ksi) steel offers improved corrosion resistance compared to traditional reinforcing steels. Efficient use of its higher strength can enable decreased reinforcement congestion. However, to efficiently exploit the available strength, sectional shear design models must adequately account for the higher expected strains in both longitudinal and transverse reinforcement. This paper presents the test results of eight shear-critical beams used to validate and enhance existing shear capacity models. Specimens were longitudinally reinforced with ASTM A1035 Grade 690 (100 ksi) steel and transversely reinforced with either ASTM A1035 Grade 690 (100 ksi) or ASTM A615 Grade 400 (60 ksi) steel. Overall specimen heights of 1000 mm (39.4 in.) and a constant shear span-depth ratio of 3.0 were used. The main test variables were the longitudinal reinforcement ratio and the steel type for the transverse reinforcement. The load-deflection response, ultimate load-carrying capacity, and mode of failure were of primary interest. The shear capacity of the new test specimens and other published data were compared against analytical shear design models. Good agreement in the shear capacity predictions was achieved from a modified form of the CSA A23.3 capacity model, which directly accounts for the reinforcement strains at the critical section. © 2015, American Concrete.
Garay-Moran J.D.D.,DIALOG |
Lubell A.S.,Read Jones Christoffersen Ltd. |
Lubell A.S.,University of British Columbia
ACI Structural Journal | Year: 2016
Steel reinforcing bars conforming to ASTM A1035 have enhanced corrosion resistance and significantly higher tensile strength compared to conventional reinforcing steel grades. However, the impact of the unique stress-strain characteristics of this steel on the failure modes and strength prediction models is not yet fully understood. This paper reports on the laboratory testing to failure of eight large-scale specimens having small shear span to effective depth ratios and containing or omitting web reinforcement. All specimens were longitudinally reinforced with deformed A1035 steel bars with measured stresses at the peak load from 695 to 988 MPa (100 to 143 ksi)-significantly higher than the design stress limits defined in current codes of practice. Members without web reinforcement failed in a brittle manner after the formation of diagonal cracks joining the loads and supports. For members containing web reinforcement, the shear span to effective depth ratio and the longitudinal reinforcement ratio were both found to influence the failure mode and post-peak ductility. It was possible to develop designs that could exploit the high reinforcement strength while exhibiting acceptable serviceability characteristics and adequate ductility at failure. The safety of capacity predictions using ACI ITG-6R-10 provisions is presented. Copyright © 2016, American Concrete Institute.
Andermatt M.F.,AECOM Technology Corporation |
Lubell A.S.,Read Jones Christoffersen Ltd.
ACI Structural Journal | Year: 2013
It is well-known that arch action in deep concrete members provides a beneficial increase in strength. However, while specific design code provisions are available for steel-reinforced deep members that account for this influence, current design code provisions for members containing internal fiber-reinforced polymer (FRP) reinforcement do not consider the capacity obtained from arch action. Strut-and-tie-based modeling approaches for FRPreinforced members were developed through the adaptation of existing models for steel-reinforced concrete deep members. When compared to test results for large-scale members with small shear span-depth ratios (a/d), the recommended strut-andtie model (STM) is shown to be in better agreement than existing shear provisions for FRP-reinforced members. The proposed STM is also shown to accurately account for influences on capacity from the reinforcement ratio, reinforcement stiffness, and overall member height. Copyright © 2013, American Concrete Institute. All rights reserved.
Shoaib A.,Rally Engineering Inc. |
Lubell A.S.,Read Jones Christoffersen Ltd. |
Lubell A.S.,University of Alberta |
Bindiganavile V.S.,University of Alberta
ACI Structural Journal | Year: 2014
At the member scale, very few previous tests reported for shearcritical steel fiber-reinforced concrete (SFRC) members have examined specimens with depths greater than 300 mm (11.8 in.), preventing a detailed assessment of the so-called size effect in shear for SFRC. This paper reports on laboratory results of 12 SFRC specimens with an overall height from 308 to 1000 mm (12.1 to 39.4 in.), and a constant shear span-effective depth ratio of 3. Specimens contained normal or high-strength SFRC with 1% volume fraction of hooked-end steel fibers and different longitudinal reinforcement ratios, but no stirrups. The test results show that the steel fibers increase the shear capacity relative to geometrically similar reinforced plain concrete members. The normalized shear stress at failure, however, was observed to decrease as the member depth increased, indicating that a size effect in shear occurs in SFRC members without stirrups. Modifications to the ACI 318-11 provisions for shear in SFRC members are proposed Copyright © 2014, American Concrete Institute. All rights reserved.
Tassew S.T.,University of Alberta |
Lubell A.S.,University of Alberta |
Lubell A.S.,Read Jones Christoffersen Ltd.
Construction and Building Materials | Year: 2014
This paper reports on tests conducted to establish the influence of chopped glass fibers on the mechanical and rheological properties of ceramic concrete produced using a phosphate cement binder. Two different ceramic concrete matrices were studied, containing either sand or lightweight expanded clay aggregates. Fiber volume fractions between 0% and 2% were examined. The addition of glass fibers into ceramic concrete had little influence on the compressive strength and modulus of elasticity but resulted in significant increases in flexural strength and direct shear strength, regardless of the matrix type or fiber length. The results also showed that the compression, the flexure and the shear toughness all increased with an increase in the fiber content, while the workability decreased with an increase in fiber content. Overall, the results indicate that glass fiber reinforced ceramic concretes can be produced with workability and mechanical properties that are suitable for application in building elements. © 2013 Elsevier Ltd. All rights reserved.
Adebar P.,University of British Columbia |
DeVall R.,Read Jones Christoffersen Ltd. |
Mutrie J.G.,Jones Kwong Kishi
NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering | Year: 2014
New requirements have been developed for the design of members not designated as part of the seismic-force-resisting system in the 2014 edition of CSA A23.3, which is the Canadian equivalent to ACI 318. For shear wall buildings, which is the predominate type of building constructed in Canada, an interstory drift envelope is defined as a function of the global drift demand determined at the top of the gravity-load frame from an analysis that includes the effect of torsion. The variation of interstory drift over the upper stories was developed from the results of numerous nonlinear dynamic analyses of shear wall buildings. The prescribed envelope also accounts for the nonlinear shear deformation in the plastic hinge region of shear walls as was observed in experiments. This nonlinear shear deformation, which currently is not accounted for in state-of-the-art nonlinear analysis of shear walls, greatly increases the interstory drift demands on the gravity-load resisting columns over the plastic hinge region of shear walls. The seismic design requirements for gravity-load resisting columns and bearing walls depend on the inelastic flexural deformation demands on the member. When seismic demands on gravity frames are determined using a linear model, the requirements are determined from how much the induced bending moment exceeds the factored bending resistance of the member. The limit ranges from 5.0 to 0.5 times the factored bending moment resistance for columns from special moment-resisting frames to thin walls with a single layer of reinforcement, respectively. The detailing requirements for gravity-load resisting beams are also based on how much the calculated bending moment exceeds the factored bending resistance. Factored resistances are used as a simple way to compensate for uncertainty in displacement demands. New axial load restrictions have been placed on columns and bearing walls with a minimum dimension less than 300 mm to account for the fact that these members can suddenly lose all vertical load carrying capacity.
DeVall R.,Read Jones Christoffersen LTD
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium | Year: 2010
Practicing Structural Engineers provide an important and rich source of knowledge and experience that can be a valuable resource in the development of structural design codes. Their role can range from initiating changes and requirements to informing and shaping suggestions from others. Their comments can help decide the need for a change and whether it will address few or many structures, whether it will be practical or impractical in the field, whether it will be costly or not; and what the overall impact will be on the whole construction process, not just on the structural design. A few examples are given illustrating the involvement of structural designers and consultants in the development of earthquake code requirements and guidelines.
Voth A.P.,Read Jones Christoffersen Ltd |
Packer J.A.,University of Toronto
Tubular Structures - Proceedings of the 15th International Symposium on Tubular Structures, ISTS 2015 | Year: 2015
Branch plate-to-circular hollow section (CHS) connections are often chosen as an easy-tofabricate and cost-effective option. Branch plates can be slotted through the CHS and welded to two opposing faces to produce a through plate connection, where strengthening is required; however, design equations are not available at present due to limited research. The results of a finite element study, presented here, indicate that the behaviour of through plate-to-CHS connections closely match the sum of branch plate-to-CHS connection behaviour in tension and compression for a given geometric configuration. A partial design strength function, shown to be valid for a wide range of connection geometries, which is the sum of existing design recommendations for branch plate-to-CHS connections in tension and compression, is proposed for through plate-to-CHS connections. © 2015 Taylor & Francis Group, London.