Minimization of CO2 Emissions for Spread Footings under Biaxial Uplift Using a Big Bang-Big Big Crunch Algorithm

Abstract

A procedure is developed to minimize CO2 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 CO2 emissions and compare designs developed for loading outside of the kern area with analysis procedures when loading is within the kern area. The CO2 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 CO2 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 low-CO2 emission designs when detachment of the soil from the footing occurs to low-CO2 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.