Several structural systems rely on a specific hierarchy between their constitutive elements, which results in topological constraints on the feasible patterns that can describe them. Folded, corrugated, or creased surface structures require this bipartition, also called two-colouring, between independent wavy and smooth directions. Finding a valid pattern for complex design problems is not straightforward and identifying relevant ones is important as creasing can either strengthen or weaken a structure. This paper presents a way of tackling such a design problem, by focusing on the roof of the Great Courtyard of the British Museum, revisiting this structure with a creased shell to increase its bending stiffness in the key directions. The methodology includes two-colour topology finding of corrugated patterns, parametric structural analysis, and simple structural optimisation through data analysis for topological combination, which opens new research avenues for performance-informed topological exploration.@en

Structural design is a search for the best trade-off between multiple architecture, engineering, and construction objectives, not only mechanical efficiency or construction rationality. Producing hybrid designs from single-objective optimal designs to explore multi-objective trade-offs is common in the design of structural forms, constrained to a single parametric design space. However, producing topological hybrids offers a more complex challenge, as a combinatorial problem that is not encoded as a finite set of real numbers but as an unbonded series of grammar rules. This paper presents a strategy for the generation of hybrid designs of quad-mesh pattern topologies for surface structures. Based on a quad-mesh grammar, an algebra is introduced to measure the distance between designs, find their similar features, and enumerate designs with different degrees of topological similarity. Structural design applications are shown to highlight the use of topologically hybrid designs as a surrogate for obtaining multi-objective trade-offs.@en