Behavior of Concrete Block Masonry Beams and Walls (Dissertation Sample)

Behavior of Concrete Block Masonry Beams and Walls
By
A Dissertation
Submitted to the Faculty of Graduate Studies
through the Department of Civil and Environmental Engineering
in Partial Fulfillment of the Requirements for
2017
© 2017
Behavior of Concrete Block Masonry Beams and Walls
By
APPROVED BY:
__________________________________________________
…………, External Examiner
…………………………..
__________________________________________________
Mechanical, Automotive & Materials Engineering
__________________________________________________
Civil and Environmental Engineering
__________________________________________________
Civil and Environmental Engineering
__________________________________________________
Civil and Environmental Engineering
15 May, 2017
ABSTRACT
ACKNOWLEDGEMENTS
I would like to express my deepest gratitude to my advisor and supervisor, Professor Sreekanta Das, for his relentless guidance, caring, patience, and providing me with an excellent atmosphere for conducting research. I would also like to thank rest of my committee members: Dr. Riahi, Dr. Cheng, and Dr. Carriveau for their guidance. I must thank ……… at the ………. for taking the responsibility as the external reviewer of my dissertation. I would also like to thank Dr. Bennett Banting for guiding my research for the past several years and helping me to develop my background in Masonry Structures. Last but not the least is my sincere thanks go to CMDC located in Mississauga, ON;CON-TACT Masonry Ltd. located in Windsor, ON; and NSERC for financial and in-kind support, without those it would not be possible to undertake such an expensive and challenging endeavour.
Also, many thanks to Lucian Pop, Matt St. Louis, and Patrick Seguin for their assistance. Thanks to Kyle, Hossein, and my fellow graduate students for the help in my work. Finally, I would like to say thanks to my family for their patience, guidance, support and belief in me. Without their persistent help this dissertation would not have been possible.
Chapter 1GENERAL INTRODUCTION
Masonry construction utilizes different materials for developing masonry structures; such components include reinforcing steel, grout, mortar, and masonry units. The masonry structure strength depends upon the interactions of the aforementioned components. Construction of masonry prisms is undertaken using grout, mortar, and concrete masonry units (CMUs). The specific compressive strength for masonry is denoted as ƒ'm, which an engineer specifies; and it is utilized throughout the design procedures of masonry. This kind of strength features lower and upper bounds that the Building CodeRequirements and Specification for Masonry Structures (the code) (MSJC, 2008). This chapter reviews previous works on masonry prisms, beams, and walls.
Masonry construction activities are physically demanding and have high risks of work-based injuries. This is caused by undertaking heavy physical tasks that include grouting, laying bricks/ blocks, handling bricks/blocks, dismantling and erecting scaffolds (Davis 2002; Spielholz 2006). For example, a standardized Concrete Masonry Unit with dimensions of 8”×8”×16” weighs between 28 and 35 lb, and masons typically lays between 150 and 250 CMUs each working day. Within brick masonry works, a mason lays an average 1000 bricks every day (Schneider & Susi 1994). Masons are required to bend, twist and lift while laying blocks/bricks. Laying such a quantity of blocks/bricks every day could trigger considerable physical load, leading to musculoskeletal disorders (MSD) among masons. According to a recent report from the Bureau of Labor Statistics (BLS) (2009), masonry construction is considered a high –risk specialty trade with non-fatal incident rates of 191.5% for every 10,000 equivalent full-time employees as well as 2,640 recorded injuries. Schneider and Susi (1994) discovered that masonry possessed the second –ranked incidence rate for all trades of construction over injuries with gone working days because of overexertion arising from lifting. Additionally, they reported that associated costs from medical care for masons appeared highest for all construction works.
As cited earlier, masonry work features a considerable physical demand (Hess et al. 2010; Entzel et al. 2007). Van der Molen et al. (2004) discovered that most demanding activities were one-handed repetitive brick lifting as well as two-handed block lifting. For the laborers (mason assistants) pulling/ pushing wheelbarrows, carrying materials, and manual lifting for over four hours every day emerged as the most physically demanding tasks.
According to BLS (2009), in 2008, being struck by the objects accounted for the many masonry work injuries with a figure of 27%, falls came in second with 21% and overexertion was ranked third with 12% for all masonry –related injuries. The most common muscoskeletal disorder (MSD) among masons was low back pain (LBP) followed by neck, knee, and wrist/hand injuries (Construction Safety Association of Ontario 2008; Goldsheyder et al. 2002).
Additionally, masonry workers come into contact with harmful substances including Silica dust, which can trigger severe respiratory illness and in some cases fatality (Occupational Safety & Health Administration, 2002). Different studies have suggested some controls aimed at reducing the MSD risks within masonry tasks. Such controls comprise of using equipments for lifting blocks of more than 40 1b, pumping mortar to platforms, block/brick stacks to about 50cm (1.7 feet), and adjustable scaffolds for keeping working height in between 60 and 90 cm (Fabers et al. 2009, Schneider & Susi 1994, Davis 2002). Other research have suggested engineering controls such as using lightweight blocks (Hess et al. 2010; Van der Molen et al. 2008; Anton et al. 2005) in reducing masonry workers’ ergonomic loads.
According to BLS (2009), masonry construction claiming 23 fatalities alongside a 0.012 fatality per 100 equivalent workers on full-time basis is not considered as high fatality risk trade. Falls from elevated points with 43.5% as well as contact with the objects having 30.5% of all accident cases constitute the major masonry construction fatality causes of fatalities. The aforementioned statistics strongly indicate that masonry workers safety should be accorded significant attention.
Seemingly, masonry structures constitute the popular construction style of low-rise structures in both developing and developed countries globally (Ghorbani et al., 2013). According to Frankie et al. (2013), such buildings account for over 75% of building populations in several countries. Despite representing a huge portion of building stock, masonry structures have a remarkable history of poor performance in areas that experience earthquakes (Zhao et al., 2009).
The statistics in table 1 below describe typical homes and housing market in 2000 (Source: National Association of Home Builders, 2000).
Table 1: Typical homes and housing market in 2000
Garage

2 cars (65%)

Bathrooms

1-1/2 or less (7%); 2 (40%); 2-1/2+ (53%)

Bedrooms

2 or less (12%); 3(54%);4 and more (34%)

Stories

Single story (48%); 2or 1-1/2 story (49%)

Average size

2000 sq. ft.

Number of housing

1.54 million (80% single family)

Overall housing units

107 million (about 50% single –family)

Ownership rate

67%

Form of purchase

8% (numerous funding options)

Price of new homes

200,000 dollars

Median family income

45,000 dollars

Population

270 million (24% rural, 76% urban)

1 Summary OF LITERATURE REVIEW
This chapter provides summary of literature review completed. The focus of this literature review is to determine the previous research work completed on (i) …….. (ii)….., and (v).
1.1.1 Compression Testing of Masonry Prisms
Drysdale and Hamid (2008, 1979) provided an understanding regarding the best testing methodology for acquiring the compressive strength of masonry. These studies conducted tests on masonry prisms made of half block units and as well as made of full block units to determine the effect of block unit size on the compressive strength of the masonry prism. The results revealed that utilizing half block in the prism specimens provides similar outcomes as obtained from full block prism specimens (Drysdale and Hamid, 1979). The study concluded that the block size in laboratory prism testing may be smaller compared to those utilized in actual construction; however, the results obtained from prisms made of reduced size units in the lab can provide accurate prediction of compressive strength.
The masonry strength is also dependent upon the component interaction in the masonry structural system. Extensive investigation of the component interaction in the prism specimen subjected to axial compression load was completed. These studies founded considerable effect of individual component strength on the compressive strength of masonry prism specimens. It was concluded that the strength of fully grouted masonry prism specimen is dependent less on mortar joints; hence, increasing the strength of mortar joint twice reduces the compressive strength by 3% for grouted prisms and 16% for hollow prisms (Drysdale & Hamid, 1979). Additionally, small differences in the thickness of mortar joints could be overcome easily. Hence, the study found that the strength of mortar does not have a much effect on the compressive strength of masonry (Drysdale and Hamid, 1979). Type of m...