A novel topology optimization sizing design method applied to a two-pile cap structure with a full nonlinear comparison

Abstract

In this paper, a novel multi-material topology optimization method based on Bidirectional Evolutionary Structural Optimization (BESO) is proposed. The method employs a two-loop approach to optimize two-pile cap structures. The first loop focuses on minimizing structural compliance, thereby reducing the structure’s weight for a given material volume constraint. In the second loop, concrete elements exceeding their strength limits are iteratively replaced with steel elements to ensure a safe stress level for the obtained topology. The steel area is determined based on the equivalent principal forces of finite elements classified as steel. To demonstrate the effectiveness of this optimization method, a comparative analysis is conducted between a two-pile cap system designed using the Strut-and-Tie method and optimized topologies with final volume fractions of 55% and 70%. The optimized two-pile cap structures are evaluated through volume and weight analysis, as well as nonlinear finite element analysis to identify potential failure modes. The obtained designs achieve the required safety level for the design load while considering manufacturing constraints and reducing concrete volume.