A Metaheuristic Approach to Skew Reinforcement Optimization in Concrete Shells Under Multiple Loading Conditions

Abstract

This paper deals with the optimization of reinforcement in concrete shell elements. A metaheuristic approach based on a genetic algorithm is presented and called Skew Reinforcement Design in Reinforced Concrete Two Dimensional Elements with Multiple Loading Conditions (SRD2DMLC): it is an evolution of the method called Skew Reinforcement Design in Reinforced Concrete Two Dimensional Elements (SRD2D) extended to Multiple Loading Conditions (MLC). SRD2D is a design tool written in C++ that could be linked as a post processor to any commercial finite element structural analysis program. The internal actions obtained from elastic analysis of the structure are used to calculate the minimum amount of reinforcement able to guarantee structural safety. SRD2D is able to handle only one load condition at a time, but in everyday design situations a structure is almost never subjected to a single load case, but to a large number of them. Different load arrangements are, in fact, chosen to address all the possible situations that the structure can undergo in its life. SRD2DMLC is able to determine (SRD2DMLC determines or SRD2DMLC can be used to determine) the minimum reinforcement required to address all the simultaneous load cases used in the design of a structural element, that is, the combinations of maximum/minimum internal actions used in the design. The use of SRD2DMLC demonstrates that the total reinforcement able to satisfy multiple load conditions is less than the envelope of the solutions obtained analysing the single load cases alone with SRD2D. SRD2DMLC has been validated against SRD2D and Microsoft Excel solver on a prestressed curved slab bridge showing an average gain respectively of 3 and 14%.