BLAST LOADING OF CONCRETE BEAMS REINFORCED WITH HIGH-STRENGTH DEFORMED BARS. Technical Report R-226. Type C
Economical blast-resistant concrete structures can be constructed by reinforcing concrete members with highstrength deformed bars if such members can meet the requirements of adequate strength and ductility under blast loading and limited deflections and formation of cracks under static service loads. A theoretical study and a series of beam tests were made to determine if concrete members reinforced with high-strength deformed bars can meet the above requirements. In the theoretical study, the influence of the amount, yield strength, and ductility of the tensile steel and the amount, location, and yield strength of the compression steel on the strength and ductility of a concrete beam is discussed. Then, the influence of the amount and yield strength of tensile steel on the stiffness of a beam is presented. The minimum yield-load factor (ratio of the beam's static yield resistance to the static service load) required to limit deflections to any given amount is presented as an equation and is plotted for various span-todepth ratios. In the tests, sixteen simply supported concrete beams reinforced with high-strength deformed bars (91,600 psi yield stress) were subjected to static and dynamic uniform loads and their behavior observed. Eight beams were conventionally reinforced, and eight were partially prestressed. The prime purpose of the prestressing was to limit the cracks and deflections. Both types of beams were subjected to long- and short- duration loads. Several beams were loaded dynamically more than once to determine their resilience and to study the problem of multiple-shot damage. The static and dynamic tests are reported, evaluated, and compared with theory. Equations for the static collapse deflection and the maximum dynamic deflection of a uniformly loaded concrete beam are presented. It was concluded that the two major factors which may restrict the use of high-strength steel in blastresistant design are the inability of such a steel to elongate a required minimum amount and excessive deflections and/or cracks of beams reinforced with high-strength steels under static service loads. The tests demonstrated that more resistance can be gained with a lesser amount of high-strength steel than lower grades of steel and that chromium-alloy steel of the type used in this investigation has a sufficient amount of ductility for use in simply supported beams. Both the theoretical study and the experimental tests indicate that excessive deflections may be controlled by prestressing the tensile steel. (auth)
- Research Organization:
- Naval Civil Engineering Lab., Port Hueneme, Calif.
- NSA Number:
- NSA-17-030632
- OSTI ID:
- 4703581
- Report Number(s):
- AD-408447
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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