Title: Uses and Limitations of High Strength Steel Reinforcement
Author(s): ACI Committee 439
Publication: Journal Proceedings
Appears on pages(s): 77-104
Keywords: bars; beams (supports) ; bending (reinforcing steels) ; bond (concrete to reinforcement) ; building codes; chemical analysis; columns ( supports) ; concrete construction; concrete slabs;connections; construction costs; continuously reinforced pavements.
The use of high quality concrete reinforced with steel of Grade 60 and designed by ultimate strength theory has been a success. Structures combining these three elements can exhibit economy, gracefulness, and resistance to high overloads. Girders and beams can be of more pleasing proportions and columns can carry greater loads, thus leaving large interior areas column free. Resistance to high overloads such as produced in earthquakes has been demonstrated not only in the laboratory, but in the field as well under actual earthquake conditions. Engineers are constantly striving to utilize every advantage offered by each structural material. This committee report concerns the high strength steel reinforcement with f,h60 ksi (42.2 kgf/mm’)). Covered are the main structural elements, columns, beams, and slabs. The influence of seismic, ACI, ASTM, and European specifications are enumerated. Limit design and comparative costs are among subjects covered which may influence greatly future demand for this material. The information included will help the designer use not a new material, but one of newly developing attributes. While this report concerns mainly steel with yields in the 60 ksi (42.2 kgf/mm) to 70 ksi (49.2 kgf/ mmz) range, following reports will probably deal with steels of higher yields. Judging by the speed of design and material development shown in the past, that time will not be far off. This report deals primarily with the use of high strength reinforcing steel in the design and construction of reinforced concrete buildings. Although the use of high strength reinforcement in continuously reinforced concrete pavements is discussed, its use in particular structures outside the building field such as water tanks, sewage treatment plant facilities, highway bridges, and port facilities are not separately discussed. Concrete reinforced with high strength steel (fl/ 2 60 ksi) is not a new material, but one of new developed attributes. This report examines some of these qualities. The critical structural characteristics of major components of buildings and highways are examined. The influence of higher strength concretes and steels are charted. Example background material included is code influence, European specification provisions, limit design and cost data.