1283
4610.005
Not Given
Design and Construction of Lintels for Concrete Masonry Buildings
Article
National Concrete Masonry Association
1953
1-36
N
In designing residential and commercial buildings of concrete masonry, one problem constantly recurring is the design of horizontal members spanning openings in the walls. These horizontal members, commonly called lintels, function as beams in supporting the weight of the wall and other loads over the openings, and transmit these oads to the adjacent masonry. They may be made of cast-in-place or precast reinforced concrete, of structural steel shapes, or they may be of reinforced masonry construction.There are, at present, various sources of information on precase or cast-in-place reinforced concrete lintels and beams, such as “Facts About Concrete Masonry, “Concrete Masonry Handbook”, and the “CRSI Design Handbook”. The data contained herein has been prepared to supplement such existing material on ordinary types of lintels and, in addition, to present information on lintels made of lightweight concrete and reinforced concrete masonry. It is hoped the booklet will be of assistance to the architect and structural engineer, reducing to some extent the tedious and repetitious work frequently involved in the design of lintels.
The principal types of lightweight aggregates used in the manufacture of lintels are expanded shale or clay, expanded blast furnace slag and steam boiler cinders. In some localities pumice and scoria may be sed.
Lightweight aggregates vary substantially in physical properties between different types and also in any given type. It is particularly important, therefore, when designing mixes for concrete of a specified strength to do so on the basis of test data on the particular aggregate involved.
Where such test data are not available from the ggregate supplier or other source, Table E will serve as a rough guide in selecting mix proportions for trial batches. Type IA (air entraining) portland cement and graded aggregate (0-½ in.) with 50 per cent to 70 per cent passing the No. 4 sieve have been assumed.