Masonry Magazine August 1967 Page. 10
Right-A 4 ft. by 8 ft. brick wall specimen being prepared for a transverse strength test. An air bag placed between the wall and a rigid backing board is inflated to subject the specimen to a uniform transverse load over 7 ft. 6 in. span.
Left-An 8 ft. brick wall specimen ready for test in the one million pound compressive testing machine in the Geneva laboratoriese SCPRF. The machine is capable of testing wall specimens up to 15 ft. high. The test specimens are instrumented to measure both vertical shortening and lateral deflections while under load.
engineering study of the use of thin load-bearing brick walls as the structural systems of multi-story buildings up to 18 stories in height. The results of this study were published in a leading architectural magazine in June of 1952. The engineering design concept, on which this report and its recommendations were based, was developed by C. B. Monk, Jr., now Manager of Structural Research for SCPRF.
While the theory was sound, and was based on accepted structural engineering design principles, it needed to be verified by extensive laboratory testing and experimental investigations before it could be recommended to and accepted by the design professions in the United States. The apparent urgencies of other research and development activities prevented SCPRF from undertaking such an extensive structural research program until some ten years later. Consequently, the contemporary bearing wall concept lay dormant and all but forgotten in this country until 1962. In the meantime, the Swiss were making great strides in the use of load-bearing brick walls in the design and construction of high-rise buildings up to 17 and 18 stories in height. Their design concepts are based on the results of an extensive research and testing program beginning in 1946, and have now spread to other European countries where high-rise load-bearing brick buildings are becoming increasingly common.
Our knowledge of what was being done in Switzerland and other European countries, plus a growing interest among some key architectural firms in this country in the potential of such a design concept, set the stage for the start of our own extensive structural testing
and research program in early 1963. The basic purpose of the program was to develop information on the structural properties and behavior of clay masonry walls that could be used in the formulation of design procedures and the updating of building codes so as to make possible the rational engineering design and construction of bearing wall buildings. While much of value has been learned from the results of the Swiss testing programs, differences in materials, methods and code requirements dictated the necessity of our obtaining our own test data based on the materials and methods used in the United States.
The "National Testing Program", as it has been loosely called, has been SCPI-SCPRF's major research activity since 1963, from the standpoint of the percentage of budget and staff time assigned to it. Planned in close cooperation with the SCPI Department of Engineering and Technology, it has become the largest single such program involving the investigation of the structural properties of brick and tile masonry that has ever been undertaken in this country-surpassing in scope and number of individual test specimens built and tested even the extensive work done at the National Bureau of Standards from about 1915 to the early 1930's.
Much of the work at the Bureau was confined to compressive testing, with little attention given to the effects of such variables as slenderness ratios, eccentricities of load and boundary conditions. Since the start of our program, over 800 compressive test specimens have been constructed with various types of brick and hollow units and tested to destruction in order to determine their ultimate compressive strengths. These spec-
MASONRY
August, 1967