Digital tools for masonry design and construction

One view of conceptual design in architecture is as a negotiation between materials and forms. The process of configuring materials: organizing them, ordering them, arraying them emerges in the creative nature of design practice and the underpinnings of this process are embodied in the tools of architectural inquiry, traditionally: sketching, diagramming, modeling and drawing, and now in the digital age: another form of modeling, in design scripting, and in simulation. Two paradigms dominate digital design tools - surface modeling tools that provide few formal boundaries and no feedback on material realities - and material-aware building information modeling tools that are pre-coded with material and assembly logics. This paper focuses on the difficult middle ground, on design tools, envisioned by architects and technologists, that seek to preserve design flexibility, while embedding design reasoning and material logics. The focus is on masonry materials and systems. Masonry has come late to BIM because of its many forms, types and patterns and because its ability to adapt to complex shapes, make it difficult to instantiate in current BIM platforms. This paper reviews and analyzes four notable masonry buildings, and envisions the computational tools that would support the design, detailing and analysis of these buildings. It represents one component of a comprehensive project, funded by the masonry industry, to develop a software specification and workflows for integrated computational tools to support masonry design and construction. 1.0. INTRODUCTION Contemporary architectural practices engage a wide range of digital tools for the exploration of complex forms. The use of surface and solid modeling allows for the rapid generation of formal propositions - but with few clear strategies for assessing the structural or constructional implications of these propositions. CAD systems that are based on parametric modeling and design scripting facilitate the process of geometric generation, but do not host the semantics necessary to assess the implications of complex geometry. In sophisticated practices, architects embed their knowledge into the models implicitly, and argue that the means of architectural production map in some way onto the means of building production - thus making the implicit explicit (Schon 1992). Other design practices rely on specialized architectural consultants such as Front and Gehry Technologies to help "rationalize" their forms, via the creation of sophisticated parametric models imbued with the consultancy's fabrication knowledge (Derix 2009). This material agnostic or amaterial approach to conceptual design is generally supported by surface modeling tools such as Rhino, form-Z and Maya. A second approach in the development of building propositions lies in the use of building information modeling or BIM tools, in which the geometric descriptions of architectural elements such as walls, columns and beams are instantiated within a parametric model, and geometric elements are linked to functional descriptions of the objects. This geometric-functional linkage, embedded in the software by its developers, allows the BIM software to assist the architect by negotiating between building objects as they are placed and refined in the building model (Lee, Sacks et al. 2006). A potential limitation of the BIM approach is that the geometric-functional linkage is supported primarily for normative construction assemblies, and generative ideas beyond these norms are not supported. In addition, early-stage conceptual design is not easily accomplished in BIM environments, as the geometric-functional linkage cannot be asserted early in a design process where floor plates, column grids, and elevations are as yet undefined. The amaterial and the BIM approach are not mutually exclusive, and in many design practices it has become the norm to start with a surface model and transition to BIM at the later stages of design. This transition leads us to consider the role and integration of material knowledge into the models in both phases: do the early surface models require a consideration of materiality and structure or can such considerations be delayed until later stages of design when BIM tools become more relevant? At what point in the building