Introduction to Strength Design of Reinforced Bearing Walls

In this section, we shall study the behavior and design of reinforced masonry wall elements subjected to combinations of axial force and outof- plane flexure. In the context of engineering mechanics, they are beamcolumns. In the context of the MSJC Code, however, a “column” is an isolated masonry element rarely found in real masonry construction.

Masonry beam-columns, like those of reinforced concrete, are designed using moment-axial force interaction diagrams. Combinations of axial force and moment lying inside the diagram represent permitted designs; combinations lying outside, prohibited ones.

Unlike reinforced concrete, however, reinforced masonry beamcolumns rarely take the form of isolated rectangular elements with four longitudinal bars and transverse ties. The most common form for a reinforced masonry beam-column is a wall, loaded out-of-plane by eccentric gravity load, alone or in combination with wind.

For example, Fig. 6.11 shows a portion of a wall, with a total effective width of 6t prescribed by Sec. 1.9.6.1 of the 2008 MSJC Code.