Collapse‐resistant performance of RC beam–column sub‐assemblages with varied section depth and stirrup spacing

Summary Four reinforced concrete (RC) beam–column sub-assemblages designed with different span-to-depth ratios and two with varied stirrup spacing were tested, and associated pseudo-static analyses were conducted to investigate their collapse resistance under gravitational loading. The span-to-depth ratio was varied from 4.57 to 8.0, and the stirrup spacing was increased from 10 cm to 20 cm. The experimental results indicated that the resistance enhancement decreased with increasing span-to-depth ratio in the arch phase and the opposite was true in the catenary resistance. The specimen failed to recover its peak arch resistance in the catenary phase as the span-to-depth ratio was reduced to 4.5. Significant shear failure was observed when the stirrup spacing was increased, and it induced premature catenary action under the gravitational loading. The pseudo-static analysis results suggested that the catenary action was effective only if the peak arch resistance could be recovered. Hence, the peak arch resistance should be regarded as the collapse resistance for RC members with lower span-to-depth ratios. Also, the dynamic increase factor increased with plastic deformation and span-to-depth ratio in the catenary phase. This indicated that the empirical formulae recommended in current available guidelines are only suitable for alternate load path analysis without considering the catenary action. Copyright © 2014 John Wiley & Sons, Ltd.

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