Saskatchewan Centre for Masonry Design
About the Saskatchewan Centre for Masonry Design
The College of Engineering at the University of Saskatchewan, the Saskatchewan Masonry Institute (SMI) and the Government of Saskatchewan formed a partnership to expand and enhance advanced education in masonry design through the establishment of the Saskatchewan Centre for Masonry Design (SCMD). At the 2008 Masonry Design Awards, SMI President Luc Durette announced the endowment of $1.25 million dollars to the College of Engineering, a collaborative donation by the Saskatchewan government and the SMI.
“The Centre will ensure that masonry is an integral part of training engineers how to effectively and efficiently design masonry systems using all elements of masonry such as brick, stone, block, tile, and mortar.” Said Luc Durette
“Thanks to the support of the province and the Saskatchewan Masonry Institute, we expect the Saskatchewan Centre of Masonry Design to become a centre of excellence in training engineers in Canada”
– Dr. Janusz Koziński, former Dean, College of Engineering , U of S
The Saskatchewan Masonry Institute has been an integral force in ensuring that the skill needs of the masonry industry are addressed. Along with teaching engineering students how to design in masonry, there is a need for workers to bring these designs to fruition. Dominic Lula, Treasurer of SMI and Vice-President of City Masonry said “In order to move forward as an industry we need qualified people through the entire process of bringing a masonry project online. We need the designers who can create an effective design, and we need workers who can install masonry systems to exacting standards.”
SMI is also actively involved in an apprenticeship program and supports the development and training of the workforce through provincial and national initiatives. Mr. Iula said “We have a responsibility to transfer knowledge and skills to the next generation of workers, as well as the engineers. All of us who have enjoyed the benefits of the masonry industry need to conserve that legacy for future generations. And it all starts with good design.”
The endowment for the SCMD will go a long way to produce well rounded engineers with advanced knowledge in masonry, as well as provide opportunities for new research to ensure the industry is on the leading edge.
One of the many initiatives in the works is the development of a new Engineering complex. This complex will house the new SCMD, several state of the art classrooms, a large lecture theatre, a student services centre, design project rooms, office space for student, faculty and research groups.
The SCMD has already produced award winning research, and papers that have been presented at both national and international conferences as well as published in renowned engineering journals. Graduates of the SCMD now move on in their profession with an advanced knowledge of masonry design which they can use throughout their career. The Centre continues to support new students who advance the work of previous graduates as well as explore new avenues of masonry research.
Saskatchewan Centre for Masonry Design Research Abstracts
Towards the Reconciliation of the Empirical and Rational Design Provisions of CSA S304-14
Author: Amir Rezaeivahdati
Supervisor: Dr. Lisa R. Feldman Department of Civil and Geological Engineering, University of Saskatchewan
Masonry structures in Canada are designed in accordance with CSA S304-14 which includes both empirical and rational design provisions. The two design methods result in inconsistent outcomes in certain cases. This thesis investigates one such case where the empirical design provisions for unreinforced, vertically spanning, non-loadbearing, exterior concrete block walls subject to wind load result in less conservative outcomes than the rational design provisions. This discrepancy of design outcomes can indicate either the inadequate levels of safety of the empirical design method or unnecessary conservatism of the rational design method. The goal of this study is to contribute to the reconciliation of the two design methods included in CSA S304-14 for the aforementioned case.
A review of past experimental investigations suggests that parameters influencing the flexural tensile strength of walls include mortar type, support conditions, wall slenderness ratio, and the load application method. An experimental program was conducted to provide additional data in areas where test data was lacking: walls constructed using mortar cement mortar, walls with slenderness ratios equal and greater than 16, and walls with realistic support conditions. A database was compiled using test results from the past and the present experimental investigations, and was used to perform a reliability analysis for unreinforced concrete block walls subject to out-of-plane loading. The reliability analysis was conducted using a Monte Carlo simulation and the unfactored rational equation as the limit state function. Results were used to provide recommendations for the empirical provisions of CSA S304-14 assuming a minimum acceptable reliability index equal to 2.5 based on past investigations.
Walls with slenderness ratios equal to or greater than 16 consistently resulted in reliability indices lower than 2.5. Walls with a slenderness ratio equal to 12 resulted in reliability indices lower than 2.5 when subjected to a 1 in 50 years wind pressures equal to 0.53 kPa and 0.29 kPa, respectively, for the minimum and maximum values of internal pressure. Potential correlation of the different included parameters may have influenced the results and, therefore, no changes to CSA S304-14 were proposed. It was, however, recommended that the standard include a commentary to inform users of the lack of quantitative evidence supporting the safety of unreinforced masonry walls subject to wind when designed according to the empirical provisions, in particular for increasing slenderness ratios and 1 in 50 years wind pressure.
Cold Weather Admixture System for Low Temperature Masonry Construction
Author: Ouafi Saha, third year Ph.D. Candidate
Supervisors: Dr. Mohamed Boulfiza and Dr. Leon D. Wegner Department of Civil and Geological Engineering, University of Saskatchewan
Cement-based materials are, by far, the most used construction materials in the world. They are composite materials made of aggregates and paste. The paste itself is made of water and, in most cases, Portland cement. Several chemical reactions start when these two materials are mixed together; they are called the hydration reactions or, more commonly, the hydration reaction as a meta-reaction. Like other chemical reactions, when the temperature drops, the rate of the hydration reaction decreases up to the point where there is no water left in liquid form. When this happens, strength gain becomes very slow and permanent damage to the cement paste can occur. This is a major problem for concrete and masonry construction in cold weather.
As it pertains to mortar and grout used for masonry construction, two approaches can be seen in the literature to deal with this problem. The first is to cure the masonry under controlled thermal conditions, which can range from heating the mixing water to a complete heated enclosure; this approach is the one adopted by the majority of the current codes and regulations. The second approach aims to reduce the effect of low temperature by using chemical admixtures, which act usually as accelerators, freezing depressants and in some cases as water reducers. The exploration of the second approach is the subject of this project.
The object of this presentation is to show the progress made towards the goal of developing and evaluating a Cold Weather Admixture System (CWAS) for masonry construction from available commercial products. Identification of admixtures that will be used in our experiments and replication of some results for concrete from the literature have been done. A statistical design based on the response surface method was used to minimize the freezing point of masonry mortar. The best admixture candidates from the freezing point experiments were tested for their effects on the compressive strength of mortar samples. The effect of precuring samples in ambient temperature before exposing them to low temperatures was studied for various precuring periods.
This research project is funded by the Saskatchewan Masonry Institute through the Saskatchewan Centre for Masonry Design and by the Natural Sciences and Engineering Research Council of Canada.
Evaluation of Contact and Non-Contact Lap Splices in Concrete Block Masonry Construction
Authors: Kawsar Ahmed and Dr. Lisa R. Feldman
Contact and noncontact lap splices, where the lapped bars were located in adjacent cells, were tested in both double pullout and wall splice concrete block specimens. Either replicate specimens of each type were tested to evaluate whether differences in the reported quantitative results were statistically significant. Visual observations of the incurred damage were also reviewed to identify the resulting failure modes. A statistically significant difference was found between the results of the double pullout and wall splice specimens with the same reinforcing arrangements, and for the different reinforcing arrangements in the same specimen type. Specimens with contact lap splices failed due to bar pullout. Evidence of bond loss at the grout-block interface was observed for specimens with noncontact lap splices and appeared to have influenced the resulting failure mode and lap splice resistance.
Evaluating the effectiveness of double pullout concrete masonry specimens with contact and non-contact lap splices
Authors: Kawsar Ahmed and Dr. Lisa R. Feldman
Sixteen double pullout specimens reinforced with 15 mm diameter deformed steel bars with 300 mm lap splice lengths were tested. One half of the specimens were constructed with contact lap splices, where the spliced bars were located in the same cell, while the other half had non-contact lap splices, where the spliced bars were located in adjacent cells. All specimens were constructed in running bond with all cells fully grouted. The reinforcing bars in the specimens with contact lap splices generally yielded, while those specimens constructed with non-contact lap splices attained, on average, 52% of the theoretical yield load. The difference in the mean maximum load recorded for the two specimen types is significant at the 99% confidence level. Visual observations show that larger scale specimens may be more appropriate for the evaluation of non-contact lap splices when the bars are located in adjacent cells.
A rationalized approach for determining splice length requirements in reinforced masonry
Authors: R.D. Kelln and Dr. Lisa R. Feldman
Splice and development length requirements significantly impact the safety, constructibility, and economy of masonry walls. Due to a lack of research in this area, provisions for bond in CSA S304.1-04 are taken directly from CSA A23.3-04: Design of Concrete Structures. The provisions for reinforced concrete design do not account for all parameters influencing bond in reinforced masonry. In contrast, provisions in American code TMS 402-11/ACI 530-11/ASCE 5-11 are based on test results of double splice pullout specimens. While various configurations of pullout specimens have been used to evaluate splice length requirements in masonry, researchers studying bond in reinforced concrete construction have identified shortcomings in using this type of specimen. Furthermore, results of a recent masonry study established that wall splice specimens developed higher tensile resistances and higher strains in the spliced reinforcement as compared to the reinforcement in double splice pullout specimens. This study critically examines available literature related to bond research in reinforced masonry. Differences between current Canadian and American codes, research philosophies used in masonry and reinforced concrete research and respective code calibrations, and specimen types are discussed. The discussion highlights that further work is required to refine and calibrate Canadian masonry bond provisions. Based on these findings, it would seem most appropriate to use wall splice specimens designed to fail in bond prior to the yielding of reinforcement to achieve this goal.
Comparison of Wall Splice Specimen Test Results with Current Code Provisions for the Development and Splicing of Reinforcement in Masonry
Authors: R.D. Kelln and Dr. Lisa R. Feldman
Relatively few research efforts have focused on development and lap splice length requirements for reinforced masonry, despite the significant impact of these requirements on the safety, economy, and constructability of masonry walls. The Canadian masonry provisions for splice lengths in CSA S304.1-04 are taken directly from the Canadian concrete design standard, CSA A23.3-04, thus do not reflect factors exclusive to masonry construction. Provisions in American code TMS 402-13/ACI 530-13/ASCE 5-13 are based on test results of double splice pullout specimens, but may be overly conservative due to shortcomings of the specimen type chosen.
The objective of this research was to examine splice lengths needed for flexural masonry elements reinforced with bar sizes typically used in Canadian masonry construction through the testing of wall splice specimens. Presented herein is a discussion of preliminary results of calculated splice capacities. A regression analysis of splice capacity versus splice length is presented. Average test-to-code calculated ratios of splice lengths of 1.36, 1.78, and 2.20 result for the CSA S304.1-04 Class A provisions, Class B provisions, and TMS 402-13 requirements respectively. Test-to-code calculated ratios decrease with increasing bar size when evaluating CSA provisions whereas these ratios show no distinct trend when assessing TMS 402-13 provisions.
Bar size factors for lap splices in block walls subjected to flexure
Authors: R.D. Kelln and Dr. Lisa R. Feldman
An experimental investigation was conducted to evaluate bar size factors used for the calculation of required lap splice lengths according to US and Canadian codes for concrete block masonry walls subjected to out-of-plane loads. Wall splice specimens were constructed in running bond with all cells fully grouted, and were tested under monotonically increasing four point loading. Specimens were longitudinally reinforced with either No.15, 20, or 25 reinforcing bars with varying lap splice lengths that were sufficiently short to ensure that a bond failure would precede a failure in flexure. Modifications to the bar size factors included in both codes were derived from the resulting test data. The evaluation of the test data shows that decreases to lap splice lengths could be considered for walls subjected to out-of-plane loads. which would facilitate construction.