Computations of Characteristic Compressive Strength and Design Vertical Load Resistance of Brick Masonry

The latest version of NBC-2016 [National Building Code of India 2016, Volume 1, Part 6: Section 4: Masonry, Bureau of Indian Standards, SP 7:2016, New Delhi] includes provisions and recommendations for design of unreinforced and reinforced brick masonry and other masonry units. While the design philosophy of unreinforced and reinforced brick masonry continues to be based on permissible stresses, assimilation of statistical significance in latter is quintessential and needs more attention. In design of reinforced concrete elements led by limit state principles, the ultimate stress in concrete is computed as a function of characteristic compressive strength of concrete which is an important stress block parameter. The application of a similar design philosophy to structural masonry requires more probabilistic perspective and arriving at the characteristic compressive strength for masonry would serve as a predominant factor. Also, some of the leading international masonry codes of practice such as British Standards, European Standards and Australian Standards have adopted the practice of limit state designs for unreinforced and reinforced masonry encompassing several masonry units. The design of masonry structures in compression based on limit states as practiced by western codes involves three main components—the characteristic compressive strength of masonry, stress (or capacity) reduction factors and the design vertical load resistance of masonry. This research article primarily focuses on unreinforced brick masonry by determining these three key factors with a backdrop of limit state methods and evaluates its influence in the design. Thus, the computed design vertical load resistance of brick masonry is compared with results obtained by some of the mentioned international masonry codes. Further, design charts have been developed to determine the design vertical load resistance of brick masonry which serves as a ready-reckoner for computations. © 2022, The Institution of Engineers (India).