Influence of blockaid chairs on compression and out-of-plane behaviour of reinforced masonry walls

ABSTRACT

Changes in Australian Masonry Standards and National Code of Construction for reinforced masonry (RM) under compression impress the need of a grout annulus and vertical bar confinement using 6 mm tie bars. Maintaining the verticality and centricity of reinforcement and restraining them with the tie bars is challenging and time consuming. BlockAid have designed masonry bar chairs to align and restrain the reinforcing bars central in the block cores. This paper presents an investigation to ascertain the performance of BlockAid bar chairs in supporting the reinforcing bars in the RM walls subject to vertical compression and out-of-plane loads. The mean compressive strength in the fully grouted RM walls with BlockAid bar chairs was determined equivalent to the control specimen which sustained maximum load of 3100kN, compared to 3030kN for the BlockAid sample. Strain in the vertical steel bars, with BlockAid bar chairs, remained compressive throughout the loading with no evidence of buckling. The out-of-plane test results of BlockAid walls were similar in terms of failure modes, load-displacement behaviour and steel strain variations. These observations conclude that BlockAid bar chairs are effective in restraining the vertical bars against buckling and do not compromise the compression and bending capacity of RM walls.

KEYWORDS:

• Reinforced masonry
• restrainer bar chairs
• buckling
• compression
• out-of-plane bending

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Tatheer Zahra

Tatheer Zahra is a focused, motivated and result oriented Lecturer in Civil Engineering with 10 years experience in undergraduate and post-graduate teaching, research, project supervision and industrial services. Tatheer has proudly represented the Queensland University of Technology in Australia and overseas as an outstanding Science, Technology, Engineering and Mathematics (STEM) female candidate, teaching and presenting papers. Tatheer continues to grow her teaching and research skills with excellence in concrete and masonry structures and new genre composite materials.

Christopher Rafferty

Christopher Rafferty is one of the founding directors of BlockAid Pty Ltd, a company that designed and developed bar chairs for reinforced masonry to ensure best practice construction in order to achieve compliance to building Standards and Codes and provide confidence in this versatile building material for all stakeholders.