¹ Structural Engineer, Parsons Brinckerhoff Halsall Inc., Toronto, ON, M4P 1E4, Canada, email dlaird@halsall.com

ABSTRACT
CSA S304.1-04 “Design of masonry structures” uses an engineered design method (limit states design), but also permits the use of an empirical design method. The empirical approach is only allowed for unreinforced masonry and only if the building and its location are within specified limits for building height, seismic hazard index and hourly wind pressure. Many locations in Canada are ruled out by the seismic and wind limitations. Those locations remaining are mainly in parts of the Prairies and Ontario. When unreinforced masonry walls are designed for wind and seismic loading in accordance with the engineered design method, the walls are often significantly stronger than required by the empirical design method. Should this be allowed to continue or should the two design methods be reconciled? That is the dilemma. This paper discusses the two design methods and gives example calculations to compare the two. The relevant changes to the two design methods, the design loadings, and masonry construction over the past 50 years are discussed. Some relevant differences with the current American masonry code are also mentioned. Possible reasons are examined as to why the empirical design method has had such a successful history and why the empirical design method continues to be permitted. Some recommendations are included.

KEYWORDS: empirical design, limit states design, flexural tensile strength, wind load, seismic load, reliability analysis

471.pdf

¹ Professor, Department of Civil Engineering, University of Calgary, Calgary, AB, T2N 1N4, Canada, ngshrive@ucalgary.ca
² Coordinator, Canada Masonry Design Centre Calgary Office, 2725 12th St NE, Calgary, AB, T2E 7J2, Canada, guzman@canadamasonrycentre.com

ABSTRACT
Clauses for the design of masonry arches have been introduced into the Canadian masonry design standard (CSA S304) for the first time. In the engineered section the clauses are purposefully broad in concept as there are so many possibilities for arch shape, span and depth. Specifics, for example on how many spandrels should be placed in a road or railway bridge are avoided, as is lateral stability of the arch. The clauses therefore are aimed at the design of the arch itself, requiring design as a fixed arch if the abutments are fixed. The alternative is for the designer to allow for estimated relative movement of the abutments or design the arch as a two-pin arch. In the assessment of live-loading, stability is considered allowing a maximum of three hinge locations to be produced. These can be reinforced. For more information on arch analysis and design, the designer is referred to a document available from the Canada Masonry Design Centre. Tables have been developed for the empirical section of the code specifying minimum column widths for low-rise arches of different spans and depths supported on columns. The formulae and basis of the calculations are provided. This is to allow designers to use small span arches in veneers of either brick or block without having to do detailed calculations.

KEYWORDS: arch, design, analysis

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¹ Dr, Ceram, Stoke-on-Trent, Staffordshire, ST4 7LQ, UK, geoff.edgell@ceram.com

ABSTRACT
The Round Foundry in Leeds was the first site in the UK where all of the trades were brought together for the production of static steam engines. The buildings, eleven in total, were built in the nineteenth century, the latest in around 1875. They included cast and wrought ironwork and massive timber roof trusses, all of which were of interest; however this paper will focus on the brickwork fabric. The buildings were largely derelict but there was a desire to bring them back into use as apartments, offices, restaurants and bars. This paper describes the investigation into the properties of the brickwork and how the site was developed to be suitable for modern use. Of particular relevance was the compressive strength of the walls of what had been at one time the massive machine assembly hall. The buildings were listed as being of historical interest and hence retention was a priority but this was in circumstances where local damage due to frost, water, salts and movement was evident. Consequently the desire to retain appeared at times to conflict with need to make commercial decisions about the value and earning potential of the buildings in the future.

KEYWORDS: historical brickwork, round foundry, sampling, testing

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¹ MSc, PhD student, Federal University of São Carlos, Civil Engineering Dept, ernestofortes@hotmail.com
² Undergrad Student, Federal University of São Carlos, Civil Engineering Dept, dorinhapp@hotmail.com
³ PhD, Professor, Federal University of São Carlos, Civil Engineering Dept, parsekian@ufscar.br
⁴ MSc, Brazilian Portland Cement Association, claudio.silva@abcp.org.br
⁵ PhD, Professor, Federal University of São Carlos, Statistics Dept, polpo@ufscar.br
⁶ PhD, Professor, Federal University of São Carlos, Statistics Dept, dtmd@ufscar.br

ABSTRACT
Compression strength is the most common quality control test of concrete blocks. Before testing, a flat and perpendicular surface on each face of the block is necessary to allow a reasonable low dispersion of results. Cement paste is the most commonly used capping material in local Brazilian tests, where recently the permission of grinding instead of capping was added to local codes.
This work is aimed to experimentally evaluate the possibility of using dry materials – such as hardboard, plywood and fibreboard, with thickness of 2.5 mm, 3 mm, and 12 mm respectively – on capping, to replace cement paste. The tests have also included the use of grinding. A total of 90 blocks were tested for every type of capping, divided into three nominal resistances of blocks (4 MPa (B4), 8 MPa (B8) and 16 MPa (B8), gross area). Data and results were analyzed, and it was possible to notice the influence of capping on blocks strength.
A statistical analysis was carried out to evaluate the influence of each capping on the compressive strength of blocks.
The block tests’ results have indicated low variation coefficient for each kind of capping. In general, results of characteristic values are similar, except for cases of low resistance blocks (B4) with fiberboard and plywood – whose differences exceed 10% when compared to cement paste. The use of dry materials for capping can ease of use the test procedure with great reduction time and laboratory space (in the case of capping with cement) when compared to cement paste and grinding.

KEYWORDS: capping, concrete block, compressive strength

105.pdf

¹ Senior Staff II – Structures, Simpson Gumpertz & Heger Inc., 41 Seyon Street, Waltham, MA, 02453, USA, bpstrohman@sgh.com
² P.E. (CA), Malden, MA, gunjeetjuneja@gmail.com

ABSTRACT
A failure investigation of a historic unreinforced masonry arch bridge with two 11.3 m (37 ft) span arches is presented. The unreinforced masonry arches were 7.0 m (23 ft) wide with a rise of 2.0 m (6.5 ft) and consisted of uniformly sized exterior granite arch-ring stones that were cut to precisely fit radially along the arch. The arches were bearing on granite skewback stones, which rested on unreinforced spread footings. The retrofit of the bridge envisioned two spans of reinforced concrete supported on two integral-abutment pile caps and one center pier with the two arches preserved for visual effect. During construction, large horizontal and vertical movements and cracks were observed. Finite-element analysis (FEA) models were created in PLAXIS and NASTRAN to assist in the structural failure investigation. The PLAXIS finite-element model evaluated the impact of the construction sequencing on the loading conditions and displacements of the bridge superstructure and surrounding soil. The NASTRAN model provided detailed response of the arches, including the development of cracks in the mortar that the PLAXIS model could not. An evaluation of the results from the PLAXIS and NASTRAN finite-element models and a comparison of these results to the structural damage observed are provided.

KEYWORDS: bridge, failure, investigation, FEA

113.pdf

¹ PE, LEED, Regional VP, Engineering Services & Architectural Outreach, Brick Industry Association, Reston, VA, 20191, USA, btrimble@bia.org

ABSTRACT
A variety of wall types have been used in landscape applications to satisfy project requirements. Two of the more unique wall systems that have been used include perforated (screen) walls and serpentine walls. Both of these walls have unique design and detailing requirements to assure their performance. This paper outlines the history of these wall types and offers some insight into past design practices. Design theories and procedures are provided that will assist designers in the practical design of these wall systems. Proper detailing requirements are outlined for these walls to perform in harsh climates. Case studies of unique projects showcasing both perforated walls and serpentine walls in building facades are provided to hopefully expand the use of these wall types in a variety of building applications.

KEYWORDS: crinkle-crankle walls, jali, landscape walls, perforated walls, pierced walls, screen walls, serpentine walls

115.pdf

¹ MSc Student, Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada, denise.sanchez@usask.ca
² Associate Professor, Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada, lisa.feldman@usask.ca

ABSTRACT
The mean lap splice resistance of No. 15 reinforcing bars with varying transverse spacing and lap splice length was evaluated in full-scale concrete block wall splice specimens. The range of the transverse spacing between bars was limited to that which allowed the bars to remain within the same cell, and included the evaluation of tied spliced bars in contact. A total of twenty-seven two-and-a-half blocks wide by thirteen course tall specimens reinforced with two lap splices were tested in four-point loading. A ll specimens were constructed in running bond with all cells fully grouted. The calculated mean tensile resistance of the reinforcement increased with increasing lap splice length, and was greater when the bars were in contact. Securing the bars in contact may have influenced the tensile capacity of the contact lap splices: higher stresses are likely to develop as a result of the bar ribs riding over each other with increasing slip. Results of the data analysis suggest that the tensile resistance of non-contact lap splices within the same cell is generally independent of the spacing between the bars; however, the slight decrease in the tensile resistance observed in select specimens with increased clear transverse spacing between the bars also suggests that the reduction in the cover distance to the block web influences bond capacity.

KEYWORDS: concrete block masonry, wall splice specimen, splice length, contact lap splice, non-contact lap splice

119.pdf

¹ M.Sc. Student, University of Saskatchewan, Dept. of Civil and Geological Engineering, 57 Campus Drive, Saskatoon, SK, S7N 5A9; rdk277@mail.usask.ca
² Associate Professor, University of Saskatchewan, Dept. of Civil and Geological Engineering, 57 Campus Drive, Saskatoon, SK, S7N 5A9; lisa.feldman@usask.ca

ABSTRACT
Splice and development length requirements significantly impact the safety, constructability, 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.

KEYWORDS: splices, reinforcement, bond, code provisions, concrete block

117.pdf

¹ M.Sc. Student, Department of Civil &Geological Engineering, University of Saskatchewan, Saskatoon, SK, S7N5A9, Canada, alk102@mail.usask.ca
² Associate Professor, Department of Civil &Geological Engineering, University of Saskatchewan, Saskatoon, SK, S7N 5A9, Canada, lisa.feldman@usask.ca

ABSTRACT
A study completed by Ahmed and Feldman concluded that the tensile capacity of non-contact lap splices, where the lapped bars are in adjacent cells, is 29.3% less than contact lap splices of the same length in masonry assemblages. An experimental program was initiated to evaluate remedial measures that may enhance the tensile capacity of non-contact lap splices such that they can achieve a similar tensile resistance to lap splices where the bars are in contact. Three different remedial techniques were evaluated to explore the effects of adding additional confinement or knockout webs within the splice region. In addition, wall splice specimens featuring standard contact and unaltered non-contact lap splices were constructed as controls. Specimens were tested horizontally under monotonic, four-point loading. The effectiveness of the remedial techniques was determined by visual observations of the resulting distress and an analysis of the measured quantifiable data.
Three courses of knock-out webs within and adjacent to the lap splice length was the highest performing remedial technique in terms increasing the tensile capacity of the lapped bars. The decreased coefficient of variation, which also resulted, can be attributed to the elimination of poor bond at the grout-block interface between the lapped bars and prevented splitting from occurring. However, this remedial technique only managed to achieve 58.9% of the tensile capacity of specimens featuring contact lap splices, leaving further remedial methods to be explored.

KEYWORDS: bond, lap splices (contact & non-contact), concrete block construction,
mitigative construction techniques, web knock-outs, wall splice specimens

125.pdf

¹ PhD Candidate, University of Calgary, Civil Engineering Department. afoan@ucalgary.ca
² PhD, Professor, University of Calgary, Civil Engineering Department. ngshrive@ucalgary.ca

ABSTRACT
The ductility of masonry walls has been the subject of debate for many years due to the variation in methods used to evaluate ductility. An experimental program was therefore undertaken to study the effect of reinforcement on the ductility of partially grouted concrete masonry. Fifteen partially grouted concrete block walls (1.6 m long by 1.4 m high) were tested under in-plane vertical and lateral loading to examine the effect different reinforcement configurations on the ductility of the masonry. The vertical loading provided an average stress of 3 MPa (based on the net surface area). Three replicates of each of five variations of steel reinforcement were tested to allow the use of statistical analysis. The results were evaluated statistically using ANOVA (ANalysis Of VAriance) and T-tests. The definition of ductility used in the analysis of the results will be described together with an assessment of using each method of reinforcement. It was found that the vertical reinforcement in the grouted cores and the combination of vertical reinforcement together with bed-joint reinforcement provided statistically significantly improved ductility compared to plain partially grouted masonry, whereas the other two configurations (bed joint reinforcement alone) did not.

KEYWORDS: ductility, masonry walls, statistical analysis

131.pdf