INTRODUCTION The previous phase of this investigation of high-strength steel for concrete reinforcement is described in Report No. TSR-4730-7l46, which was released in July, 1957. This previous testing program was designed to provide information on the following topics, among others: (a) The shear (primarily) and flexural (secondarily) strength of restrained Tee-beams reinforced with steel of approximately 80 ksi yield point for main reinforcement and with standard steel for web reinforcement. (b) The formation of diagonal tension cracks and flexural cracks and the width of flexure and shear cracks at various loads and particularly at "design loads" (say, half the ultimate loads). (c) Deflections at "design load" of beams of this kind. (d) The validity of the Illinois shear investigations in regard to their applicability to high strength reinforcement. (e) Extension of the range of information on shear failures by a substantial number of tests with variables (such as r, p, a/d) outside the Illinois range. It is believed that adequate information on these points has been furnished by these tests. At the same time a number of important phenomena have been observed during these tests which appeared to warrant further investigation before definite design recommendations could be made for the use of high-strength reinforcement. Firstly, it was observed that in some cases negative flexural cracks through the flange of the Tee-section were so large at "design" load as to be considered objectionable for construction practice. Secondly, it was noticed that diagonal-tension cracks in the web of the Tee-section at "design" loads were also large and numerous enough to be considered objectionable. Thirdly, it was found that the use of the usual method of calculation for ultimate flexural strength which does not include explicit strain relations for the steel and concrete leads, in many cases, to a rather large underestimate of the actual flexural strength of doubly-reinforced Tee-beams with high strength steel. Lastly, no beams without web reinforcement were tested. To complete the information on the shear strength of Tee-beams with high-strength reinforcement, and to test the applicability of various theories of shear strength of unreinforced webs additional test data seem desirable.


Civil, Architectural and Environmental Engineering

Research Center/Laboratory(s)

Wei-Wen Yu Center for Cold-Formed Steel Structures


Reinforced Concrete Research Council
United States Bureau of Public Roads



Publication Date


Document Version

Final Version

Document Type

Report - Technical

File Type