Masonry Magazine April 1965 Page. 23
FLASHING AND WEEP HOLES
JOIST ANCHORS
MECHANICAL SPACE
BOND BREAK
EDGE BEAMS
BOND BREAK
BRICK WALLS-STEEL JOIST
Typical detail showing on 8" brick bearing wall with a steel joist floor system.
UTILITY WALL-TILE AND CONCRETE SLAB
A 12" utility wall with a tile and concrete slab bearing wall detail.
project consist of a 5-inch brick outer wythe with 1½ inches of insulated cavity and an inside bearing wythe of 5 inches. Inside bearing partitions in these structures are usually 6 and 7 nches in thickness. There are many loadbearing brick apartment buildings n Switzerland from 14 to 18 stories n height. Some of the 15 and 16-story apartment buildings are built with 10-nch brick walls. These walls, along with interior bearing partitions of 6 and 7 inches, carry the loads.
Loadbearing buildings are also used n England, the tallest one being in Birmingham, which is 12 stories tall. The exterior wall is a cavity wall with 41½-inch exterior wythe, a 2-inch cavity and a 9-inch interior bearing wythe. In Aarhus, Denmark, there is 16-story loadbearing brick apart-nent building. The exterior walls of his building are 14 inches of solid orick, with interior bearing walls be-ng 9 inches in thickness.
Structural Requirements
Structural requirements for load-wearing buildings are relatively easy o satisfy, particularly in residential uildings such as apartments, hotels, Hormitories and other structures which ave repeating box-like elements. The llowable compressive stresses in brick masonry run as high as 500 psi and somewhat higher when tests on he proposed construction are per-formed. Masonry is relatively weak tension. One of the benefits of load-Bearing construction is, in effect, a ost-stressing which overcomes ten-ile bending stresses which might therwise be critical. The recommend-d allowable tensile bending stresses nbrickwork are 28 to 36 psi.
The third consideration of the de-ign of these buildings is the resistance o lateral forces. There ordinarily are resisted by shear resistance of ma-sonry walls parellel to the lateral force. A shearing stress as high as 40 to 50 psi may be safely used for unrein-forced masonry. Overturning of the structure due to lateral force must also be considered but it is seldom a critical problem.
There are two simple basic schemes for bearing-wall construction: One be-ing bearing cross walls or bearing cross partition construction in which floor systems span from partition to parti-tion which are the bearing elements. The second basic system is that com-posed of bearing exterior walls and bearing longitudinal partitions, such as corridor walls. And, of course, there are combinations of these which are used with two-way concrete slab constructions, such as a waffle slab.
The floor system selected for a particular bearing-wall building will depend upon a number of things. Sometimes joist systems of tile, con-crete or steel are desirable, while other times cast-in-place concrete sys-tems may be best. Wood construction, although not often used in major buildings, does offer low initial cost. In order for thin walls to be used in loadbearing buildings it is imperative that the wall and floor systems work together. The floor systems must act as diaphragms which will transmit la-teral loads to the walls parallel to the direction of the force so that these cross walls can carry the lateral forces to the ground by the shearing resist-ance.
Very often foundation requirements are simpler for bearing-wall buildings than for buildings of other types. This is true because the forces are delivered (Please turn раде)
The Ponnley Park urban renewal project in Pittsburgh, Pa. Tesso Katselas are the architects. The exposed brick bearing walls provide six elements: structure, separation, economy, acoustics, fire protection and finish.
23
MASONRY
April, 1965