Title: Tensile Strength and Diagonal Tension Resistance of Structural Lightweight Concrete
Author(s): J. W. Hanson
Publication: Journal Proceedings
Appears on pages(s): 1-40
Describes the tests employed and the results obtained in an extension of a previous study of diagonal tension resistance reported by the author. This extension of the original program involves lightweight concrete beams of longer span and lower steel percentages. An important conclusion, that diagonal cracking load should be considered as the ultimate load for non-web-reinforced beams, has been confirmed. A large number of 6 x 12-in. cylinders from the beam concretes were broken by the split-cylinder tension test. Good correlation was established between this indirect tension measurement and the shear resistance of the beams at diagonal cracking. This correlation shows that diagonal tension resistance of lightweight concrete varies from approximately 60 percent of that of the similar normal weight concrete to nearly 100 percent, depending on the particular lightweight aggregates used. Proposed ultimate load design recommendations are made for structural lightweight concrete. These are in general accord with the recommendations of the ACI-ASCE Committee 326 on shear and diagonal tension for normal weight concrete. It has been found that diagonal tension strength of the lightweight concretes is affected by the same variables as affect the resistance of normal weight concrete. The difference between the two types of materials is one of magnitude of diagonal tension resistance and not of fundamental difference in behavior. The proposed design recommendations also provide for the fundamental differences in tensile resistance that exist between the various lightweight aggregates. A combination of compressive strength and split-cylinder tension testing provides a convenient and safe measure of the ultimate diagonal tension resistance to be associated with each of the various aggregates.