Optimization of UHPC beams under flexural loading: A numerical and experimental investigation

Ultra-high-performance concrete is a material with enhanced mechanical properties compared to conventional concrete. These characteristics make it possible to conceive structural elements with reduced cross-sections and lower reinforcement ratios (RR) to withstand the same load capacities as conventional concrete elements. However, UHPC beams with low RRs exhibit low ductility indexes due to localization phenomena. The proposed methodology uses a genetic algorithm routine to generate an optimized cross-section to reduce UHPC consumption, decreasing the RR. The optimization methodology was based on finite element models to increase load capacity while maintaining a target minimum ductility. The experimental program tested three reference rectangular beams with different RRs and one beam with an optimized cross-section. The tested beams were then modeled using the finite element method in the Abaqus software through a modeling technique that considered the variability of the material properties by dividing the element's volume into parts with different material properties. The results showed that changing the cross-section's format can increase load-bearing capacity while maintaining target ductility.