Masonry Structural design

Steps in Strength Design of Unreinforced Bearing Walls

In the 2008 MSJC Code, design of unreinforced bearing walls is similar to  the design of panel walls, except that axial load must be considered. In Sec. 3.2.2 of the 2008 MSJC Code, no explicit equations are given for computing flexural strength. The usual assumption of plane sections is invoked, and tensile and compressive stresses in masonry are to be assumed proportional to strain.
Nominal capacities in masonry are reached at an extreme fiber tension equal to the modulus of rupture (Sec. of the 2008 MSJC Code), and at a compressive stress of 0.80 f ′ m.
Compressive capacity is given by Eqs. (3.11) and (3.12) of the 2008 MSJC Code:

The strength reduction factor, φ, is equal to 0.60 (Sec. of the 2008 MSJC Code). Unlike the allowable-stress provisions, the strength provisions of the 2008 MSJC Code require a direct stability check using a moment magnifier.


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