#Masonry stack bond in seismic category full

Seismic Design Category E & F have an additional requirement that the horizontal reinforcement be at least 0.0015 the gross cross-sectional area of walls that are not part of the lateral-force resisting system.

#Masonry stack bond in seismic category full

For example, Building Code Requirements for Masonry Structures requires stack bond masonry in Seismic Design Category D and higher to be solidly grouted hollow open-end units, fully grouted hollow units with full head joints, or solid units with a maximum spacing of 24 in. When stack bond construction may be subjected to seismic loads or winds of hurricane velocity, consideration must be given to additional requirements and restrictions as may be consistent with local codes, local experience, and engineering practice. This is equivalent to the minimum reinforcement stated above for a nominal 4 in. Anchored masonry veneer must have horizontal joint reinforcement, of at least one wire size W1.7 (9 gauge) (MW11) or larger, spaced at a maximum of 18 in. (1219 mm) on center or using joint reinforcement. This requirement can be met using either bond beams spaced not more than 48 in. Although stack bond typically refers to masonry constructed such that the head joints are vertically aligned, the Code defines stack bond as masonry laid such that the head joints in successive courses are horizontally offset less than one quarter the unit length, as illustrated in Figure 1.Īll stack bond construction is required to have a minimum area of horizontal reinforcement equal to 0.00028 times the gross vertical cross-sectional area of the wall. 1) includes criteria for walls laid in stack bond. From this it can be seen that properly reinforced stack bond masonry can be designed to be as strong as running bond construction.īuilding Code Requirements for Masonry Structures (ref. The value of joint reinforcement as a means of strengthening concrete masonry in the horizontal span is indicated in Figure 4 which shows the relative flexural strength with and without joint reinforcement. The flexural strength of stack bond walls spanning horizontally can be increased significantly by the use of bond beams or joint reinforcement. The use of pilasters or grouted cells will also be effective in increasing the resistance to concentrated loads. Stability will not be jeopardized if allowable stresses are not exceeded, but the use of reinforced bond beams will aid in distributing concentrated loads. In stack bond masonry, heavy concentrated loads will be carried down to the support by the particular vertical tier or “column” of masonry under the load, with little distribution to adjacent masonry. Compressive strength is similar for stack and running bond construction. Excluding running bond construction, the most popular and widely used bond pattern with concrete masonry units is stack bond.