Page 40 - Design of Reinforced Masonry Structures

INTRODUCTION 1.9

and architects to select appropriate design criteria for masonry construction. Concerned
professionals in the masonry industry recognized the need for a single, national consen-
sus standard for the design and construction of all types of masonry. In 1977, the ACI
and ASCE agreed jointly to develop such a standard with the help and support of the
masonry industry. The MSJC was formed with balanced membership of building offi-
cials, contractors, university professors, consultants, material producers, and designers
who were members of the ACI and ASCE. TMS joined as sponsoring organization in
1991. Through this effort evolved the two documents (published as a set in one docu-
ment) titled the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/
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TMS 402) and the Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602) ,
aimed at consolidating and advancing existing standards for the design and construction
of masonry. Approval of the first edition of the MSJC Code and Specification occurred in
June 1986. Public review began in 1988 with the final approval of the 1988 MSJC Code
and Specification in August 1988 [1.29].
The MSJC Code covers the design and construction of masonry structures while the
MSJC Specification is concerned with minimum construction requirements. As a source
of valuable information, commentaries for the MSJC Code and Specification were also
developed. These documents provide background information on the design and specifica-
tion provisions. They contain considerations of the MSJC members in determining require-
ments and references to research papers and articles.
The MSJC Code, Specification, and Commentaries are revised on a three-year cycle.
The first revision was issued in 1992, the second in 1995, the third in 1999, the fourth in
2002, the fifth in 2005, and the current edition in 2008. The 1995 edition included signifi-
cant changes from its 1992 version, with addition of a new chapter on glass unit masonry,
masonry veneers, seismic design, and a total reformat of the MSJC Specification. Thus, for
the first time in the history of masonry standards, brick, concrete, glass block, composite
construction, and veneers appeared in the same documents. The 2008 MSJC Code incor-
porated complete revisions pertaining to anchor bolts, seismic design requirements, and
several others design related revisions.
Topics covered in the 2008 MSJC Code include definitions, contract documents, quality
assurance, materials, placement of embedded items, analysis and design, strength and ser-
viceability, flexural and axial loads, shear, details and development of reinforcement, walls,
columns, pilasters, beams and lintels, seismic design requirements, prestressed masonry,
veneers glass unit masonry, veneers, and autoclaved aerated masonry. An empirical design
method and a prescriptive method applicable to buildings meeting specific location and
construction criteria are included. The Specification covers topics such as quality assur-
ance requirements for materials, the placing, bonding and anchoring of masonry, and the
placement of grout and of reinforcement. An important provision in the 2008 MSJC Code
is Section 1.17 which deals with seismic design requirements.

1.7 DESIGN METHODS

For many years, masonry structures have been and continue to be designed based on the
traditional allowable stress design method (also called service load method or working
stress design). In this method, a structure is proportioned (designed) to resist code-specified
service loads, which are assumed to be loads that a structure might be subjected to during
its service life. The allowable (or working) stresses used in design are a fraction of the
accepted failure strengths of materials (viz., compressive strength of masonry and yield

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Together, the two documents are referred to as the MSJC Code and Specification.