Caitlin T. Mueller

Massachusetts Institute of Technology | MIT · Department of Architecture, Department of Civil and Environmental Engineering

Many researchers have leveraged digital fabrication to reduce the climate impact of high embodied carbon material use. However, horizontal spanning structures (e.g. roofs and floors) remain challenging with respect to energy intensity and structural mass quantity, and existing low-mass construction systems, such as ribbed or waffle slabs, either re...

With the growth of computational design, geometric and performance-based design data has become increasingly important. Computation empowers designers to generate designs based on specific qualitative features, or to evaluate their performance based on user interests. This work presents a visualization framework that pairs performance mapping with...

The mass timber industry offers a compelling pathway for low-carbon structural systems in buildings, replacing carbon-intensive materials like concrete and steel with sustainably forested wood. However, conventional structural connections in mass timber construction are largely made of metallic materials, such as screws, nails, and plates. In contr...

This paper presents a novel toolpath optimization method for formwork free 3D printing of shells. The additive fabrication of shell structures without formwork has the potential to significantly reduce material waste and construction cost, thus minimizing embodied carbon across the concrete construction industry while making an often appreciated bu...

This paper presents a historical overview of thin shell foundations including built examples and existing literature on the theory and application of their engineering. Using existing structural design methodologies, material quantities are calculated in order to evaluate the environmental impact of shell foundations compared to conventional flat (...

New tools in digital design and fabrication have bolstered the design of material efficient structures with increased precision and predictability. Unfortunately, early-stage structural design is a disjointed exercise in design and analysis that excludes the untrained stakeholder. There is a clear divide between the methods designers use to explore...

Principles and precedents in efficient structural design demonstrate the advantage of designing topologies that align well with an underlying vector field, such as principal stress or principal bending moment. While there now exist methods and mature research fields for generating topologies from those underlying vector fields, an alternate approac...

Society is building at an unprecedented rate: to house over 200,000 people moving to cities each day building stock will need to double by 2060. Importantly, the embodied carbon of construction due to material extraction, manufacturing, transportation, and demolition accounts for 11% of global carbon emissions, and this number is only expected to r...

In the effort to reduce the environmental impact of buildings, floor systems remain especially challenging as major sources of material consumption, mass, and embodied energy. This paper considers one promising alternative to traditional flat slab concrete floor systems, filler slabs, which replace underutilized concrete with low-value filler mater...

Additive robotic construction of building-scale discrete bar structures, such as trusses and space frames, is increasingly attractive due to the potential improvements in efficiency, safety, and design possibilities. However, programming complex robots, such as manipulators with seven degrees of freedom, to successfully complete construction tasks...

This research outlines a new computational workflow for the design and optimization of patterned, perforated surface structures. Well-designed surface structures can be highly efficient on their own, but their potential for structural efficiency can be notably improved by deliberately introducing specific aperture patterns. Patterned surfaces can a...

There is increasing demand for automated systems that can fabricate 3D structures. Robotic spatial extrusion has become an attractive alternative to traditional layer-based 3D printing due to a manipulator's flexibility to print large, directionally-dependent structures. However, existing extrusion planning algorithms require a substantial amount o...

The modular interlocked blocks in flat structures are known in ancient buildings with pure-compression constructions. Over the last two decades, this structural bond has become relevant, studied by mechanical engineers, and material scientists due to the properties and design freedom that modular structures have. The structural hierarchy existing i...

This work fully investigates a specific timber joinery connection via experimental, analytical, and numerical methods. The selected joint is the Nuki joint: a mortised column with through-beam tenon. The experimental approach takes advantage of digital fabrication to reduce variations introduced by hand fabrication while the analytical approach bui...

This paper presents a developing platform of design strategies for concrete construction in India. More specifically, this paper will discuss three strategies for the design of horizontal spanning concrete elements. Each strategy involves a different method of structural optimization with varying performance levels based on material reduction and s...

Historic timber structures feature timber joinery connections that use interlocking geometries rather than fasteners. While timber construction since has gradually favored metallic fasteners, the longevity of historic timber structures utilizing joinery connections demonstrates their feasibility in structural systems and potential to enable sustain...

We present the first algorithm for designing volumetric Michell Trusses. Our method uses a parametrization-based approach to generate trusses made of structural elements aligned with the primary direction of an object's stress field. Such trusses exhibit high strength-to-weight ratio while also being parametrically editable which can be easily inte...

Forests worldwide are overstocked with small-diameter trees, putting them at increased risk of disease, insect attack, and destructive high-intensity wildfires. This overstocking is caused primarily by the low market value of these small-diameter trees, which are generally unsuitable for sawn timber production and yield low prices when sold for bio...

Mahendra Raj is an engineer that enjoys a challenge. Consequently, no two projects of his are the same. With a portfolio of over 250 projects and a career spanning nearly six decades, from Indian Independence to the time of this paper's writing, there is no simple explanation for who Raj works with or how he works with them. In an attempt to unders...

This paper presents a fast and flexible method for robotic extrusion (or spatial 3D printing) of designs made of linear elements that are connected in nonstandard, irregular, and complex topologies. Nonstandard topology has considerable potential in design, both for visual effect and material efficiency, but usually presents serious challenges for...

Historic timber structures feature timber joinery connections that use interlocking geometries rather than fasteners. While timber construction since has gradually favored metallic fasteners, the longevity of historic timber structures utilizing joinery connections demonstrates their feasibility in structural systems and potential to enable sustain...

While robotic spatial extrusion has demonstrated a new and efficient means to fabricate 3D truss structures in architectural scale, a major challenge remains in automatically planning extrusion sequence and robotic motion for trusses with unconstrained topologies. This paper presents the first attempt in the field to rigorously formulate the extrus...

In the United States, Cross-Laminated Timber (CLT) panels are gaining considerable attention as designers focus on building more ecological and sustainable cities. These panels, which are surface elements made from layers of orthogonally bonded layers of dimensional lumber, can speed up construction on site due to their high degree of prefabricatio...

We present the first algorithm for designing volumetric Michell Trusses. Our method uses a parametrization approach to generate trusses made of structural elements aligned with the primary direction of an object's stress field. Such trusses exhibit high strength-to-weight ratios. We demonstrate the structural robustness of our designs via a posteri...

While robotic spatial extrusion has demonstrated a new and efficient means to fabricate 3D truss structures in architectural scale, a major challenge remains in automatically planning extrusion sequence and robotic motion for trusses with unconstrained topologies. This paper presents the first attempt in the field to rigorously formulate the extrus...

Many architectural designers recognize the potential of parametric models as a worthwhile approach to performance-driven design. A variety of performance simulations are now possible within computational design environments, and the framework of design space exploration allows users to generate and navigate various possibilities while considering b...

This paper presents a fast and flexible method for robotic extrusion (or spatial 3D printing) of designs made of linear elements that are connected in non-standard, irregular, and complex topologies. Nonstandard topology has considerable potential in design, both for visual effect and material efficiency, but usually presents serious challenges for...

This research introduces new computational workflows to design structural patterns on surfaces for architecture. Developed for design but rooted in the rigor of structural optimization, the strategies are aimed at maximizing structural performance, as measured by weight or stiffness, while offering a diversity of solutions responding to non-structu...

This paper contributes new knowledge and results to the fields of topology optimization and robotic spatial extrusion through the consideration of how these methods can be used together. Specifically, a new topology optimization formulation is presented that accounts for the manufacturing constraints of uniform cross section and average member leng...

The paper presents the results of the design method for a simply supported cavity beam, along with fabrication and load testing results. An optimization algorithm determines the location and rotation of empty plastic water bottles within a prismatic reinforced concrete beam in order to reduce material usage without reducing strength. Designed for I...

Innovations in mass timber have ushered in a resurgence of timber construction. Historic timber structures feature joinery connections which geometrically interlock, rarely featuring in modern construction which utilizes steel fasteners for connection details. Research in the geometric potential and mechanical performance of joinery connections rem...

Architectural structures achieving high strength and stiffness with intelligent, but intricate geometry may now be materialisable through additive manufacturing (AM). However, conventional layer-based AM also produces parts with inconsistent structural strength - thereby limiting AM's end-use applications. Expanding on robotics-enabled AM technique...

Bending-active structures, made from elastically bent materials such as fiberglass rods, offer exciting opportunities in architecture because of their broad formal palette and ease of construction. While they have been relevant since Frei Otto’s Mannheim Multihalle (1974), recent computational developments that help simulate active-bending processe...

To be useful for architects and related designers searching for creative, expressive forms, performance-based digital tools must generate a diverse range of design solutions. This gives the designer flexibility to choose from a number of high-performing designs based on aesthetic preferences or other priorities. However, there is no single establis...

Owners of large building portfolios such as university campuses have long relied on building energy models to predict potential energy savings from various efficiency upgrades. Traditional calibration procedures for individual building model are time intensive and require specially trained personnel, making their applications to campuses with hundr...

Impact of decisions in the design process is initially high and declines as the design matures. However, few computational tools are available for the early design phase, thus an opportunity exists to create such tools. New technology opens up new possibilities to create new and novel computational tools. In this work an existing application is ada...

How can structural, functional and fabrication aspirations be most effectively integrated into digital design, without losing its conceptual inventiveness? Over the last few years, the Digital Structures research group at the Massachusetts Institute of Technology has been investigating just that. Group leader Caitlin Mueller here offers an account...

In the design of tall buildings, the lateral system that resists wind and seismic loading usually dominates the structural engineering effort; therefore, optimal lateral system design is important for material efficiency. In a shear-wall-based building, the conventional design process starts with an architect generating a floor plan, which is then...

Optimization techniques developed for additive manufacturing (AM) to maximize the structural stiffness of printed parts are often computationally expensive reformulations of classical procedures that do not typically consider the mechanical behavior introduced to the printed part by the AM fabrication process, which is layer-based, and result in pi...

In the design of discrete structures such as trusses and frames, important quantitative goals such as minimal weight or minimal compliance often dominate. Many numerical techniques exist to address these needs. However, an analytical approach exists to meet similar goals, which was initiated by Michell (1904) and has been mostly used for two-dimens...

This research follows an important body of work from the past decade, which focuses on the design of global surface geometries for compression-only structural behaviour. For example, studies in thrust network analysis have made possible the design and computation of complex unreinforced freeform shell structures that work purely under compressive f...

In the field of digital fabrication, additive manufacturing (AM, sometimes called 3D printing) has enabled the fabrication of increasingly complex geometries, though the potential of this technology to convey both geometry and structural performance remains unmet. Typical AM processes produce anisotropic products with strength behavior that varies...

The aim of this research is to solve an inverse form-finding problem: construct funicular, axial-only structures as close as possible to a target surface defined by the designer. The scope is limited to grid-like, node-and-branch only networks, which can be solved efficiently using the force density method (FDM). This problem is formulated as a lea...

Fabric and ice shells, first pioneered by Heinz Isler (Chilton [2]), are lightweight structural systems that allow for inexpensive and reversible construction of free-standing stiffened shell structures. They are of interest for exploring new structural forms and construction methods and are analogs for shells built with more permanent materials. T...

Many recent contributions in computational structural design have argued that design quality can be improved when performance feedback and guidance are part of the conceptual design process. However, the effect of multi-objective feedback and guidance tools has not been studied extensively. This paper presents the results of an educational study th...

This paper presents new research in the area of construction of building-scale structures using unmanned aerial vehicles, commonly called drones. The work follows up on a previous paper presented at the 2015 IASS Symposium by Latteur et al. [1], which focused on the feasibility of drone-based construction systems with an emphasis on localization sy...

This paper presents a new type of joints derived from a historic wooden puzzles. A rule-based computational grammar for generating the joints is developed based on the relationship between the three-dimensional shape and its two-dimensional " net ". The rhombic polyhedra family, cube, rhombic dodecahedron, and rhombic triacontahedron are fully expl...

This article presents a computational design methodology that integrates generative (architectural) and analytical (engineering) procedures into a simultaneous design process. By combining shape grammars and graphic statics, the proposed methodology enables the following: (1) rapid generation of diverse, yet statically equilibrated discrete structu...

This paper shares the authors’ experience regarding the Forces Frozen workshop developed in MIT’s Building Technology Program, within the Department of Architecture. This one-week outdoor workshop invites students to physically explore the world of structural ice shells. Ice shells are primarily created by a procedure that takes advantage of the sy...

Any non-funicular structure can be converted into an axial-only geometry with the introduction of additional loads through an external post-tensioning system. This design approach would provide architectural versatility without giving up on structural efficiency. This paper presents a physical validation of this methodology through reduced-scale mo...

In conceptual building design, an architect must simultaneously consider a variety of design objectives, including structural efficiency, total energy usage, and aesthetic expression. Multi-objective optimization (MOO) has been demonstrated to adequately account for designers’ needs and guide them towards high performing solutions early in the desi...

This paper presents “3D Sampling” as a new creative design process. Analogous to sample-based music, 3D Sampling provides conceptual and technical tools for hacking, mixing, and re-appropriating the material behavior, performance features, and structures of real world objects. Building on previous research, this paper demonstrates a new 3D Sampling...

This paper addresses the potential of multi-objective optimization (MOO) in conceptual design to help designers generate and select solutions from a geometrically diverse range of high-performing building forms. With a focus on the long span building typology, this research employs a MOO approach that uses both finite element structural modeling an...

This paper explores the use of data-driven approximation algorithms, often called surrogate modeling, in the early-stage design of structures. The use of surrogate models to rapidly evaluate design performance can lead to a more in-depth exploration of a design space and reduce computational time of optimization algorithms. While this approach has...

This paper presents a new robotic additive manufacturing (AM) framework for fabricating 2.5D surface designs to add material explicitly along principal stress trajectories. AM technologies, such as fused deposition modelling (FDM), are typically based on processes that lead to anisotropic products with strength behaviour that varies according to fi...

Funicular structures, which follow the shapes of hanging chains, work in pure tension (cables) or pure compression (arches), and offer a materially efficient solution compared to structures that work through bending action. However, the set of geometries that are funicular under common loading conditions is limited. Non-structural design criteria,...

3D Sampling is presented as a new method for comprehensive rearrangement and composition of 3D scan data, allowing multi-scale manipulation of surface texturing and subsequent fabrication and re-evaluation using 3D printing. Analogous to sample-based music, 3D Sampling contributes new frameworks, tools, and compositional strategies for the digital...

Most architectural modelling software provides the user with geometric freedom in absence of performance, while most engineering software mandates pre-determined forms before it can perform any numerical analysis. This trial-and-error process is not only time intensive, but it also hinders free exploration beyond standard designs. This paper propos...

Funicular geometries, which follow the idealized shapes of hanging chains under a given loading, are recognized as materially efficient structural solutions because they exhibit no bending under design loading, usually self-weight. However, there are circumstances in which nonstructural conditions make a funicular geometry difficult or impossible....

This paper proposes a grammar-based structural design methodology using graphic statics. By combining shape grammars with graphic statics, this method enables the designer to: 1) rapidly generate unique, yet functional structures that fall outside of the expected solution space, 2) explore various design spaces unbiasedly, and 3) customize the comb...

In architectural and structural design, current modeling and analysis tools are extremely powerful and allow one to generate and analyze virtually any structural shape. However, most of them do not allow designers to integrate structural performance as an objective during conceptual design. As structural performance is highly linked to architectura...

In the field of digital fabrication, additive manufacturing (AM, sometimes called 3D printing) has enabled the fabrication of increasingly complex geometries, though the potential of this technology to convey both geometry and structural performance remains unmet. Typical AM processes produce anisotropic products with strength behavior that varies...