Experimental damage-gas flow correlations for cyclically loaded reinforced concrete walls

The relationship between concrete damage and gas flow (permeability) has been largely unexplored. In the design of nuclear/hazardous storage facilities, an estimation of flow rate through seismically damaged structural concrete components may be critical. This work focuses on the experimental evaluation of damage-gas flow, using scaled reinforced concrete wall specimens. The method for evaluating the damage-flow rate relationship includes structural testing, damage identification, and air flow rate experiments. Concrete damage is characterized both locally and globally, via consideration of crack characteristics and drift ratio, respectively. Two phases of testing were undertaken; the first phase focuses on testing nine reinforced concrete wall panels under uniaxial cyclic loading and the second phase involves testing twelve shearwall specimens under biaxial cyclic loading. Specimens in each phase of testing had variations in geometry, material, and loading details. Information gathered in these experiments is then compared and assessed with formulae available in literature for determining leakage rates. Results indicate that concrete strength, reinforcement ratio, aspect ratio, and applied axial load have the greatest affect on the permeability of cracked concrete. The cracked permeability was minimized when using high strength concrete, high reinforcement ratios, higher aspect ratio, and larger axial loads. Likewise, the permeability increased with a reduction in concrete strength, reinforcement ratio, aspect ratio, and axial load. Comparison of the experimental air flow with formulas available in literature indicates that a reasonable and consistent estimation of leakage rate may be obtained. Lastly, a design example is presented to demonstrate the usefulness of the experimentally-developed correlations