Masonry Magazine March 1967 Page. 31
NCMA TEK 7
An information series from National Concrete Masonry Association
© 1967, National Concrete Masonry Association
Load Bearing Block in High Rise Buildings
Corridor Wall-bearing or nonbearing, transfers wind load parallel to it.
Dead load on shear walls used to develop resistance to overturning.
Combined bearing partition and shear wall.
Floors serve as horizontal diaphragms-transfer wind load to shear walls.
MARCH, 1967
Load Bearing Block in High Rise Buildings
Floor-wall connection must be capable of transferring lateral forces (composite action).
How load-bearing block is used
A growing number of designers, builders, and building owners are employing load-bearing concrete masonry in multi-story "high-rise" buildings. These buildings range from 3 to 13 stories. They are designed and constructed either as reinforced concrete masonry or as nonreinforced, depending on building height, local code, and seismic conditions. Principal benefit of the high-rise concrete masonry load-bearing construction is the economy effected by speed and simplicity. Construction sequence consists of the erection of a series of single-story structures on top of each other. Fewer trades are involved. Shoring and scaffolding are minimized. With the completion of the masonry work, finishing operations can be accomplished quickly and easily because the building is enclosed and work is protected. Little wonder the mason contractor, having just completed an eight-story 207-unit motel of load-bearing concrete block, described this method as the nearest thing to mass-produced masonry there is."
The general concept of high-rise load-bearing structures is the combined action of floors, bearing walls, and shear walls in resisting lateral forces. Floors transmit horizontal forces by diaphragm action from the exterior walls to shear walls, which in many cases are also the bearing walls. The floor system must be sufficiently rigid to serve as a diaphragm, and connections must be adequate to transfer these forces to the shear walls which carry them to the foundation. Because it relies on the composite behavior of wall, floor, and roof planes for lateral stability the high-rise load-bearing structural sistem is particularly well suited to multicellular designs such as apartments, hotels, motels, dormitories, and hospitals. The height to which these buildings can reach depends upon the strength of the reasonry walls in compression and shear, spacing of intersecting walls and floors, their connection to each other, and the shape of the structure.
Design
Analysis of high-rise load-bearing structures is straightforward and involves no special techniques unfamiliar to the practicing engineer. Such structures should be investigated by a competent engineer for their resistance to all vertical and lateral loads. Investigation will include: Bearing Capacity-In most cases, bear-