Interrelationships between Reinforcing Bar Physical Properties and Seismic Demands


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Title: Interrelationships between Reinforcing Bar Physical Properties and Seismic Demands

Author(s): J. McDermott

Publication: Special Publication

Volume: 184


Appears on pages(s): 1-6

Keywords: ductility; modulus of elasticity; reinforcing bar.

Date: 11/1/1999

Reinforcing bar physical properties are main determinants for reinforcing-bar seismic demands. Consequently, seismic codes set appropriate single upper or lower limits on reinforcing bar yield strength and tensile/yield ratio, but they do not consider the variable-parameter effects of the shape of the reinforcing-bar stress-strain curve on what tensile/yield ratios and ductilities should realistically be required of reinforcing bars in seismic-resistant structures. Therefore, a theoretical study was performed to evaluate the effect of range of allowable steel yield strength, shape of steel stress-strain curve (strain and tangent modulus of elasticity at onset of strain hardening), and beam slenderness (S/d, where S is the clear span length and d is the effective depth to the reinforcing bar centroid, Figure 1) on the minimum values of steel tensile/yield ratio and useful ductility that are necessary to accommodate 2% seismic drift by plastic hinging at the end of beams, Figure 1, of concrete rigid frames reinforced with Grade 60 steel reinforcing bars.