Paul Shepherd

• MA (Cantab) Mathematics, PhD Structural Fire Engineering
• Professor of Computational Design at University of Bath

The Automating Concrete Construction (ACORN) project explored digital workflows from the design to the construction of reinforced concrete building floor elements, reducing carbon emissions and increasing efficiency of building processes. The resulting digital tool, named SQUIRREL, enabled the design of shells, composed of prefabricated segments, t...

The construction industry has recently increased the adoption of additive manufacturing (AM, also known as 3D-printing) technologies. This review paper presents the state of the art of ground-based AM systems in construction, focusing comprehensively on developments in the material aspect towards using unmanned aerial vehicles (UAV), commonly refer...

Additive manufacturing (AM) has undergone rapid development over the past decade, yet printing parts with overhangs still poses a critical challenge, restricting the fabrication of components with arbitrary geometries. In structural optimization, incorporating overhang constraints can mitigate this issue. However, prior research has predominantly f...

Modern fully-glazed buildings in subtropical climates such as Hong Kong are susceptible to glare and overheating from high solar gains. Adaptive façades have the ability to limit glare and control daylight ingress within an optimum range, thus improving occupant satisfaction and worker productivity. Adaptive façades can also reduce the risk of over...

A comprehensive framework for the layout optimisation of rigid-jointed frame structures is proposed, addressing multiple mechanical constraints while effectively managing geometric complexity. The constraints considered include displacement, stress, and both local and global stability. Geometric complexity is controlled by minimising low-stiffness...

Millions are living in shelters around the world, often for decades. Architects are rarely trained in shelter design and as a result speculative designs are frequently impractical or insensitive to occupants. In addition, aid agency staff can lack engineering or architectural knowledge, so need support during shelter procurement. Evidence gathered...

Additive manufacturing in construction typically consists of ground-based platforms. Introducing aerial capabilities offers scope to create or repair structures in dangerous or elevated locations. The Aerial Additive Manufacturing (AAM) project has developed a pioneering approach using Unmanned Aerial Vehicles (UAV, ‘drones’) to deposit material du...

Additive Manufacturing (AM) in relation to the construction industry is an emerging technology. However, ground-based AM on construction scales may be limited by the dimensions, reach and weight of the ground-based deposition platform. Aerial additive manufacturing (AAM) can revolutionise construction-based AM by employing multiple untethered unman...

Aerial additive manufacturing (AAM) represents a paradigm shift in using unmanned aerial vehicles (UAVs, often called `drones’) in the construction industry, using self-powered and untethered UAVs to extrude structural cementitious material. This requires miniaturisation of the deposition system. Rheological properties and known hydration times are...

The construction industry is responsible for nearly half of the UK's carbon dioxide emissions and the use of an extremely large volume of concrete – the world's most widely used man-made material – accounts for more than 7% of global carbon dioxide emissions. The scale of this problem spawned research to explore the potential for structurally effic...

The geometrical variability in the joints of large-scale, doubly-curved space-frame structures can have a substantial impact on the time and cost of their construction. This paper proposes a novel framework to assess the construction complexity of space-frame structures as a factor of the geometrical variability and fabrication of their joints, to...

Additive Manufacturing (AM) methods in the construction industry typically employ ground-based deposition methods. An alternative to transform the role of AM in construction is to introduce an aerial capability. A recent project titled Aerial Additive Manufacturing (AAM), the first AM system to use untethered, unmanned aerial vehicles (or ‘drones’)...

The article is available at: https://drawingmatter.org/heinz-isler-model/

This paper provides a review of the capabilities of WAAM for manufacturing steel components for use in the construction industry, with a focus on the structural stability and design of WAAM builds. Manufacturing techniques that can be used for WAAM construction are first discussed. This is followed by a detailed review of the material and geometric...

Additive manufacturing methods1–4 using static and mobile robots are being developed for both on-site construction5–8 and off-site prefabrication9,10. Here we introduce a method of additive manufacturing, referred to as aerial additive manufacturing (Aerial-AM), that utilizes a team of aerial robots inspired by natural builders¹¹ such as wasps who...

Doubly-curved ribbed concrete shells are a materially efficient means of spanning large areas such as roofs and floors. However, the fabrication of such structures poses challenges in terms of formwork manufacturing as well as material deposition. This has led to their decline compared to more prismatic shapes such as flat slabs which can be manufa...

Courtyard blocks are well known for their tempering potential of the thermal conditions in various climates. In this paper, the building heights, orientation and interspaces of courtyard blocks are optimised for the hot-arid climate of Cairo, Egypt. Simulations are conducted using an evolutionary search algorithm within the Grasshopper parametric d...

Structural optimization methods can be extremely powerful when used at the initial, conceptual, design stage of a building or bridge structure, potentially identifying materially efficient forms that are beyond the imagination of a human designer. This is particularly important at present, given the pressing need to reduce the carbon footprint asso...

Grid shells have been widely used in various long-span public buildings, and many of them are defined over free-form surfaces with complex boundaries. This emphasizes the importance of general and digitalised grid generation and optimization methods in the initial design stage to achieve visually sound grid shells. In this paper, a framework is pre...

This chapter describes several real-world international case studies of parametric design, covering building and infrastructure design. It describes a range of different approaches, techniques and programmes used by experienced practitioners. The case studies explore the individual project requirements and constraints, the solution heuristics, impl...

Purpose Understanding the supply network of construction materials used to construct shelters in refugee camps, or during the reconstruction of communities, is important as it can reveal the intricate links between different stakeholders and the volumes and speeds of material flows to the end-user. Using social network analysis (SNA) enables anothe...

Over the last two decades, urban geometry has been shown to be a key determinant of the microclimatic conditions in urban areas. This study uses the Ladybug-tools, the plugins of Grasshopper3D to optimise building heights, street widths and orientation to maximise outdoor thermal comfort, represented by the diurnal average Universal Thermal Climate...

Concrete shells are a more sustainable alternative than plates as building floors, thanks to their effective use of concrete in compression. Although the construction of these geometrically complex structures becomes more challenging, off-site automated fabrication offers solutions to efficiently produce a shell in segments before assembling it on...

The recent reports from the Intergovernmental Panel on Climate Change (IPCC) urge for the reconceptualization of our design of the urban built environments. However, current efforts to integrate urban environmental assessment into practice in Egypt are proving insufficient. This paper utilises the Ladybug tools simulation plugins to investigate the...

Millions of forcibly displaced people are living in temporary shelters. Evidence gathered by the authors in seven countries over three years (2017 – 2020) revealed poor conditions within many shelters, including condensation, excessive temperatures, lack of privacy and poor air quality, all of which can contribute to increased stress, morbidity and...

Over the last decade, outdoor thermal comfort has become of considerable significance to urban designers and planners. In that concern, parametric design models were acknowledged for supporting the design process with iterative performance-based solutions and for being relatively less time and resource consuming. However, validation studies for suc...

Over the past two decades, there has been a marked increase in the consideration of outdoor thermal comfort by urban planners. Several researchers have developed their own models for a better understanding of the human energy exchange with their surrounding environment. Among those models developed is the Ladybug-tools microclimate model, the plugi...

Concrete is a major contributor to the environmental impact of the construction industry, due to its cement content but also its reinforcement. Reinforcement has a significant contribution because of construction rationalisation, resorting to regular mats or cages of steel bars, despite layout-optimisation algorithms and additive-manufacturing tech...

Thin, rectangular structural plates are used in a wide range of applications, including architectural sheet metal cladding, in which the magnitude of lateral deflection is much larger the material’s thickness. This study compares new experimental data with established algebraic models and assesses the influence of practicalities such as geometric t...

In this paper, we introduce geometry optimization into an existing topology optimization workflow for truss structures with global stability constraints, assuming a linear buckling analysis. The design variables are the cross-sectional areas of the bars and the coordinates of the joints. This makes the optimization problem formulations highly nonli...

The design of bending-active structures is a challenging problem, due to the high non-linearity of the activation process, the coupling between member sizing, structural shape and the deformability and buckling sensitivity inherent in the resulting lightweight configurations. Due to the large number of form-finding variables, the choice of member s...

The construction industry is responsible for nearly half of the UK’s carbon emissions, mainly due to the large amount of concrete used. Traditional formwork methods for concrete result in prismatic building elements with a constant cross-section, but the shear forces and bending moments that beams have to withstand are far from constant along their...

The expanding use of IT has brought an increase in productivity to the world of business, industry and commerce. However, this is not mirrored by an equivalent growth in the use of IT by aid agencies in post-disaster situations. We report a pioneering two-stage study which tested the appetite for the increased use of computational IT tools in this...

This paper explores the potential of thin concrete shells as low-carbon alternatives to floor slabs and beams, which typically make up the majority of structural material in multi-storey buildings. A simple and practical system is proposed, featuring precast textile reinforced concrete shells with a network of prestressed steel tension ties. A non-...

In recent years, the application of space-frame structures on large-scale freeform designs has significantly increased due to their lightweight configuration and the freedom of design they offer. However, this has introduced a level of complexity into their construction, as doubly curved designs require non-uniform configurations. This article prop...

Truss layout optimization problems with global stability constraints are nonlinear and nonconvex and hence very challenging to solve, particularly when problems become large. In this paper, a relaxation of the nonlinear problem is modelled as a (linear) semidefinite programming problem for which we describe an efficient primal-dual interior point m...

Purpose Shell structures are highly efficient and are an elegant way of covering large uninterrupted spaces, but their complex geometry is notoriously difficult to model and analyse. This paper aims to describe a novel free-form shell modelling technique based on structural harmonics. Design/methodology/approach The method builds on work using wei...

The mechanical performance of grid shells is dependent on their structural geometry and is related to the loads exerted on them. By making use of the close relationship between the design parameters for hanging models and computational form-finding, the shape optimization of grid shells considering their mechanical performance under various loading...

Truss layout optimization provides a means of identifying the global optimal arrangement of truss bars capable of transmitting a given load or loads to defined support points within a defined design domain. However, the solutions obtained are generally complex and lead to structures with far too many members to be practical, especially when fine di...

We consider the overall buckling under own weight of a thin-walled column of circular crosssection and a radius that is a hyperbolic sine function of distance from the top of the column. The maximum stress is limited to a given value, but there is no limit to the height of the column. The wall thickness is determined by consideration of local buckl...

Modern architectural design has seen a shift towards iconic doubly-curved envelopes enclosing large column-free spaces. Gridshells have long been considered an efficient solution to such designs, but their actual use in practice has not spread worldwide. For elastic gridshells, their advantages in terms of substantial material savings can often be...

Large modern buildings frequently are enclosed by lightweight, panelised, aluminium-framed facades, known as unitised curtain walls. This study shows that, in such wall systems, the established procedures for analysing the stability of structural extrusions ignore two of the three greatest causes of lateral movement in the main member, or mullion....

This paper describes an experimental program carried out at the University of Sheffield to investigate the interaction of local and distortional buckling in cold-formed steel lipped channel beams. The channels were arranged in a back-to-back configuration and a total of six tests, including three different cross-sectional geometries, were completed...

Free-form grid structures have been widely used in various public buildings, and many are bounded by complex curves including internal voids. Modern computational design software enables the rapid creation and exploration of such complex surface geometries for architectural design, but the resulting shapes lack an obvious way for engineers to creat...

Gridshells have been widely used in various public buildings, and many of them are defined over complex free-form surfaces with complex boundaries. This emphasizes the importance of general grid generation and optimization methods in the initial design stage to achieve visually sound and easy-to-manufacture structure. In this paper, a framework is...

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...

This paper describes an experimental program carried out at the University of Sheffield to investigate the interaction of local and distortional buckling in cold-formed steel lipped channel beams. The channels were arranged in a back-to-back configuration and a total of six tests, including three different cross-sectional geometries, were completed...

An Analysis of the Embodied Energy and Embodied Carbon of Refugee Shelters Worldwide. The delivery of health, food, and shelter to the 68.5 million people displaced worldwide represents a significant challenge. Camps can house hundreds of thousands of people, and the provision of shelter on such a scale uses considerable amounts of energy and const...

Cold-formed steel (CFS) construction can lead to more efficient designs compared to hot-rolled steel members as a consequence of its high strength, light weight, ease of fabrication, and flexibility in their cross-section profiles. However, CFS members are vulnerable to local, distortional and overall buckling modes. This paper develops a numerical...

Rapid global urbanisation and population growth is driving unprecedented levels of building construction, with the total worldwide floor area expected to almost double over the next 40 years. Since most of the structural material in a building exists within the floors, these present a significant opportunity for structural engineers to contribute t...

Structural silicone sealants are synthetic rubber adhesives used in the construction industry to bond glass and other sheet infill materials to the frames of windows and curtain walls. In this paper, two different algebraic expressions are proposed to describe the way in which the rotational stiffness of the adhesive connection – resistance to mome...

This paper develops a numerical model to investigate the flexural strength and failure modes of CFS back-to-back channel beams and verifies the efficiency of an optimisation framework previously proposed. The model incorporates non-linear stress-strain behaviour and enhanced corner properties obtained from coupon tests, as well as initial geometric...

Increasing pressure to reduce the life-cycle impact and material consumption of new structures is driving interest in the use of minimally processed or second-hand structural materials in new construction. Conventional structural design methods, however, assume supply chains which can deliver effectively infinite supplies of structural elements in...

Buildings are being constructed at ever faster rates, fuelled by population growth and urbanisation. The total worldwide floor area of buildings is expected to almost double over the next 40 years, the equivalent of constructing Paris every five days [1]. The majority of the mass and embodied energy (60% to 70%) in a typical multi-storey building s...

Shells have the potential to considerably reduce material consumption in buildings due to their high structural efficiency compared to equivalent structures acting in bending. Textile reinforced concrete (TRC) is a promising material for the construction of thin concrete shells due to its strength, geometric versatility, and durability. Existing de...

Shells have the potential to considerably reduce material consumption in buildings due to their high structural efficiency compared to equivalent structures acting in bending. Textile reinforced concrete (TRC) is a promising material for the construction of thin concrete shells due to its strength, geometric versatility, and durability. Existing de...

During the recent decades it has become common to enclose large buildings with lightweight, weathertight walls that hang, like curtains, from the floor edges. The frames of these curtain walls are, usually, extruded aluminium – a material whose production is highly energy-intensive. Although means of enhancing the thermal performance of building en...

This paper describes a method for the form finding of shell structures composed of both compression and tension members which may lie in one layer or two layers. The length of some of the members can be constrained to a fixed length yielding some control of the resulting form found shape. The form finding is accomplished by adjusting the nodal posi...

The paper focuses on what the authors call 'Polar Lightweight Structures'. The first part presents a collection of lightweight structures (LWS) designed and build for Antarctic conditions, with the aim of demonstrating the diversity of approaches attempted by designers. The second part of the paper presents two studies where different computational...

Steel-reinforced concrete, cast in flat prismatic forms, dominates multi-storey building construction around the world. Despite the fluidity of the material, opportunities to create efficient geometries through manipulation of form are habitually overlooked, resulting in inefficient cracked sections, high steel requirements and large carbon footpri...

Conventional structural design proceeds by establishing a rough geometry for a structure, determining internal forces, and sizing members to resist these forces. This design process assumes effectively infinite supplies of standardised elements.There are some cases, however, where structural materials are available in strictly finite quantities, or...

This project brings together modern developments in computational design, materials and construction methods to propose a novel thin-shell concrete flooring system for multi-storey buildings, aiming to create a low embodied energy and lightweight alternative to traditional reinforced concrete flat slabs.

Some naturally-occurring materials, such as timber and stone, have inherent structural capacity without the need for costly and energy-intensive processing. However, in their original forms as trees or irregular rubble, these materials are considered useless for structures, primarily because their shapes and material properties are too diverse for...

A weightless wire coat hanger bent out of its plane is one of the simplest possible structures. All it does is transfer a force and moment around a closed space curve. Assembling a family of coat hangers enables us to build up trusses and frames and if we allow an infinite number of coat hangers which overlap we can assemble plates, shells and full...

Curtain walls are lightweight, weathertight, exterior facades. They are capable of resisting wind loads, but provide no support for the building structures to which they are attached. Although they are used to enclose many different types of modern building, and although they may be designed to carry any of the outward-facing materials an architect...

Concrete is the most widely used construction material. Worldwide consumption of cement, the strength‐giving component in concrete, is now estimated to be 4.10 Gt per year, having risen from 2.22 Gt just 10 years ago. This rate of consumption means that cement manufacture alone is estimated to account for 5.2 % of global carbon dioxide emissions. C...

Parametric modelling software often maintains an explicit history of design development in the form of a graph. However, as the graph increases in complexity it quickly becomes inflexible and unsuitable for exploring a wide design space. By contrast, implicit low-level rule systems can offer wide design exploration due to their lack of structure, b...

Building Information Modelling Assessment Methods (BIM-AMs) are performance measurement systems that evaluate BIM across organisations, projects, individuals and teams. They focus priorities and help companies communicate their strategies both internally within their own businesses, and externally to other stakeholders. Currently, there are sixteen...

Fabric formwork is a novel concrete construction method which replaces conventional prismatic moulds with lightweight, high strength sheets of fabric. The geometry of fabric formed structures is therefore dictated by the behaviour of fabric under hydrostatic loading. While there are numerous examples of digital and physical modelling of this proble...

This simple paper describes an intuitive data-driven approach to reconstructing architectural building-footprints from structured or unstructured 2D pointsets. The function is fast, accurate and unconstrained. Further unlike the prevalent L-Shape detectors predicated on a shape's skeletal descriptor [Szeliski 2010], the method is robust to sensing...

This simple paper describes an intuitive data-driven approach to reconstructing architectural facade models from unstructured point-clouds. The algorithm presented yields sparse semantically-rich models that are better suited to interactive simulation than the equivalent dense-reconstructions, yet executes significantly faster than the prevalent sp...

ABSTRACT: Building Information Modelling Assessment Methods (BIM-AMs) are used to evaluate the implementation of BIM and improve its adoption in practice. Over the past nine years there have been at least 16 BIM-AMs developed in academia and industry, each offering a unique perspective on BIM performance. Despite the continual growth of BIM-AMs, th...

Whilst a significant amount of research has been carried out on the implementation of BIM in the AEC industry, far less attention has been paid to the evaluation and measurement of BIM performance. This study aims to provide an investigation into the mapping of Building Information Modelling Assessment Methods (BIM-AMs) in the Architecture, Enginee...

Codes of practice rely on the effective length method to assess the stability of multi-storey frames. The effective length method involves isolating a critical column within a frame and evaluating the rotational and translational stiffness of its end restraints, so that the critical buckling load may be obtained.The non-contradictory complementary...

In property development, the view quality contributes significantly to the property value. In many cases, the architect is constrained by the property developer to take full advantage of the view by designing large glazed facades ignoring the consequence on the energy consumption of the building caused by the conflicting orientation of the view. Th...

The research incorporated in the paper stems from the design and fabrication of a self-supporting, multi-panel installation for the Venice Biennale 2012 and operates against the backdrop of the exciting potentials that the field of curved-crease folding offers in the development of curved surfaces that can be manufactured from sheet material. The t...

Abstract: The use of bending as self forming process allows the realization of shape-resistant systems, such as grid shell structures. Here, a numerical method for optimization of the cross-section of actively bent structures is introduced. For a given load distribution , the optimisation objective consists of normalizing the bending stresses to a...

Codes of practice rely on the effective length method to assess the stability of multi-storey frames. The effective length method involves isolating a critical column within a frame and evaluating the rotational and translational stiffness of its end restraints, so that the critical buckling load may be obtained. The non-contradictory complementary...

There has been a shift in aesthetics from the modern orthogonal building envelope to more elaborate curved and folded forms. Non-orthogonal forms are often associated with complete freedom of geometry, entrusting the advancement in custom manufacturing and robotic fabrication of one-off building parts to realise the design. This paper presents a me...

There has been a shift in aesthetics from the modern orthogonal building envelope to more elaborate curved and folded forms. Non-orthogonal forms are often associated with complete freedom of geometry, entrusting the advancement in custom manufacturing and robotic fabrication of one-off building parts to realise the design. This paper presents a me...