A procedure is developed to minimize CO_2 emissions for the design of reinforced concrete spread footings subjected to biaxial bending satisfying both geotechnical limit states and structural requirements using a Big Bang-Big Crunch (BB-BC) algorithm. The objectives are to minimize CO_2 emissions and compare designs developed for loading outside of the kern area with analysis procedures when loading is within the kern area. The CO_2 emissions are associated with the extraction and transportation of raw materials; processing, manufacturing, and fabrication of products; and the emissions of equipment involved in the construction process. The CO_2 objective function is subjected to soil bearing and displacement limits, as well as bending moment, shear force, and reinforcing details specified by the American Concrete Institute (ACI 318-11). A design example is presented to compare IOW-CO_2 emission designs when detachment of the soil from the footing occurs to IOW-CO_2 emission designs when the entire base of the footing is in compression. Results are presented that demonstrate the effects of different magnitudes of eccentricities on designs.
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