Experimental investigation of strut-and-tie layouts in deep RC beams designed with hybrid bi-linear topology optimization

Abstract

This paper presents the experimental study of deep reinforced concrete beams designed with strut-and-tie models. Three different reinforcement layouts are designed with the same material quantities and for the same loading and boundary conditions. Two of the layouts are automatically generated using a topology optimization framework in which obtaining increasingly complex steel layouts is allowed. The experimental performance of these are compared to a beam designed with a conventional strut-and-tie model. Two samples are constructed and experimentally tested of each of the three designs. To limit post-processing of the reinforcement layouts, the topology-optimized designs are obtained using a hybrid bi-linear approach and an alternative reinforcement method has been used; the layouts have been waterjet cut from steel plates. The experimental study reveals that the topology-optimized reinforcement layouts have an increase in stiffness and strength compared to the conventional design. Interestingly, all specimens with topology-optimized reinforcement exhibit a similar behavior regardless of the topological complexity. This suggests that significant performance improvements are obtained when using topology optimization to generate strut-and-tie models without necessarily requiring the resulting layout to be highly complex and costly to construct.