What is the value of critique in structural design?

Practicing chefs in the kitchen can revise and refine a recipe to their own satisfaction, yet their progress need not be limited by their own opinion. What might result from allowing a fellow chef or a mentor to taste their recipe? Each taster might give his/her own personal feedback – too salty, not crisp enough – and the aspiring chef, filtering through the responses, may modify and further improve the recipe to a level otherwise unattainable without outside feedback. We find this occurrence in countless other fields; why else might athletes have coaches, and musicians have private instructors? One may be able to accomplish much through individual work, but a trained eye (or ear) observing from the outside can potentially coax an even better performance out of an individual.

Image credit: arch20

It is no different in design. Some design principles that we espouse to our students (such as constraints as drivers of design, drawing as a means of clarifying thoughts, the usefulness of studying precedents, and the iterative nature of the design process) primarily concern the designer as an individual. However, like the chef or the athlete or the musician, designers can only improve on their own to a certain degree. No matter how experienced the designer, outside feedback can add another dimension of considerations that enhance the design.

In structural design, the feedback of a more experienced engineer can be especially important in verifying the suitability and feasibility of the structure. However, that’s not to say that critique from a less experienced engineer is not useful; anyone who has not labored over the design process already has the advantage of seeing the design with fresh eyes and may perceive problems or solutions with greater ease. The act of critiquing is also a valuable exercise for the aspiring engineer, revealing the opportunity to jump into another’s design process and explore the different design decisions that were or were not made.

We emphasize that critique is an opportunity to improve a design; rather than shy away from a critique that may bash on the flaws in a design, designers would benefit from embracing the critique as a way of learning and improving from both peers and mentors.

The Happy Pontist blog discusses in detail the challenges of critiquing works of structural engineering and how to circumvent them. Read more about them here.

Assessing the Stability of Masonry Structures (part 2): Numerical and Physical Modeling

This post is second in a series covering different assessment methods for stability of masonry structures. Part 1 covered classical and equilibrium methods; this post covers suitable numerical modeling techniques as well as different examples of physical modeling for masonry stability.

4. Numerical modeling

Several methods of numerical modeling for masonry structures exist, as demonstrated by the flowchart in Fig. 10.

Figure 10: Overview of numerical modeling methods for masonry structures, adapted from [41] with [8]
As the first level of Fig. 10 suggests, numerical modeling of masonry structures can be divided into four main categories: macro-modeling, homogenized modeling, simplified micro-modeling, and detailed micro-modeling. Asteris et al. [41] provide discussions, summarized below with some additions where noted, on the differences between these modeling approaches. Fig. 11 also depicts the different numerical modeling approaches. In this section, macro-modeling and simplified micro-modeling are the focus.

Figure 11: Illustration of different strategies for modeling true masonry sample (a): (b) one-phase macro-modeling, (c) two-phase micro-modeling, and (d) three-phase micro-modeling [41]

4.1 Macro-modeling: masonry as a one-phase material

The macro-modeling approach models both bricks and mortar (or all bricks, in the case of dry masonry) as a homogeneous continuum as in Fig. 11(b). As the subsets under macro-modeling in Fig. 10 suggest, these numerical models are typically finite element models.

Continue reading “Assessing the Stability of Masonry Structures (part 2): Numerical and Physical Modeling”

What to see when visiting Cambridge, UK

Our Princeton alum, Anjali Mehrotra, is currently pursuing a PhD in historic masonry structures at the University of Cambridge, UK. We asked Anjali to take us on a campus tour in search of structural surfaces. This is what she showed us.

King’s College Chapel,  1446 – 1515

There is an abundance of vaulted structures in Cambridge, including the main gates of Corpus Christi College, Trinity College and St John’s College, which are also examples of fan vaults and are each adorned with the respective college’s crest.

Corpus Christi College 1353  and St John’s College 1511 gates

Other vaulted structures in St John’s include the cloisters of the neo-Gothic New Court, which were designed by Thomas Rickman and Henry Hutchinson between 1826 and 1831. Around the same time, another architect, William Wilkins, designed the Great Hall and Gatehouse of King’s College.

St John College Cloisters and detail Gatehouse King’s College

Professor Jacques Heyman, former Head of the Cambridge University Engineering Department, is widely considered to be one of the world’s leading experts in cathedral and church engineering. He revolutionized the analysis of masonry structures by translating plastic theory developed for steel design into theorems which could be used for stone as well. His book The Stone Skeleton: Structural Engineering of Masonry Architecture is the seminal work in this matter. His theories have been used for the analysis of various types of masonry structures including arches, spires and vaults, with the latter including Gothic style fan vaults, with perhaps the most famous example being the vault of King’s College Chapel in Cambridge. Built between 1512 to 1515 by John Wastell, the fan vault is 88 m long and 12 m in span, making it the world’s largest.

Professor Jacques Heyman and interior view of King’s College Chapel 1512-1515.

Author: Anjali Mehrotra

Prof. A’s Tedx Talk: Designing for strength, economy and beauty

Check out this video and like it on YouTube.

By 2050, 70% of the world’s population will live in cities. Structural engineers envision, design and construct the bridges and long‐span buildings those city dwellers depend on daily. The construction industry is one of most resource‐intensive sectors, and yet our urban infrastructure continues to be built in the massive tradition in which strength is pursued through material mass. In December 2016, Professor Adriaenssens gave aTedX talk “Designing for strength, economy, and beauty” at the GeorgeSchool, PA. Her idea is that our bridges and buildings should derive their strength and stiffness not through material mass but from their curved shape, generated by the flow of forces. As a result, these structures can be extremely thin, cost‐effective, and have a smaller carbon footprint and arguably they can have an esthetic quality to them.

Author: Prof. S. Adriaenssens

Assessing the Stability of Masonry Structures (part 1): Classical and Equilibrium Methods

This post is first in a series covering different assessment methods for stability of masonry structures. This post covers classical and equilibrium methods; Part 2 covers suitable numerical modeling techniques as well as different examples of physical modeling for masonry stability.

The persistence of some of the oldest structures in the world in masonry has demonstrated the high potential for masonry structures to last through various conditions over long periods of time. Masonry’s compressive strength is extraordinarily high – it is estimated that a stone pillar would have to be 2 kilometers tall in order to fail by crushing. [1] As a result, in contrast to materials such as concrete and steel that make up most of present-day structures, the limit state of masonry is often dictated by its geometry and not its material properties.

Research into the stability of masonry structures is valuable for two main reasons. Firstly, this research enables us to understand and preserve the structures of the past. Many structures of rich cultural heritage are made of masonry, but their stability is challenged by environmental and anthropogenic threats, such as earthquakes or terrorist attacks. [2–6] The second reason is forward-looking. In some areas of the world, masonry materials are abundant and are thus the most economic choice of building material. An understanding of stability in masonry structures can make possible design tools for materially efficient structures.

Examples of masonry structures are given below. Philadelphia City Hall (1901) is the world’s tallest masonry structure at 167 meters height. [A] The King’s College Chapel (1515) in Cambridge, UK is not even a fifth of the height of Philadelphia City Hall, but the complex geometry of its fan vaults make it a compelling study of masonry stability. [B] Finally, the Armadillo Vault (2016) is a prime example of how an understanding of masonry stability can inform efficient design today. [C]

Methods and theories of structural analysis for masonry structures

The structural analysis of masonry arches and structures have preoccupied countless scientists since the 17th century. In this post, studies on 1. Classical methods and 2. Limit state analysis (including equilibrium analysis and kinematic analysis) are presented. A future post will explore 3. Numerical modeling and discuss existing studies that use each method to assess masonry structures. A more comprehensive overview of studies on each analysis method can be found in [7–9].

Continue reading “Assessing the Stability of Masonry Structures (part 1): Classical and Equilibrium Methods”

Grow strong and live beautifully: Colombian bamboo structures

While the new group of senior students are getting up to speed with their senior theses, we look back in this weeks blog post on the work of Russell and Lu Lu in Colombia.

In March 2016 Russell Archer (’16) and Lu Lu (‘16) traveled to the city of Cali, Colombia and the coffee region (Spanish: Eje Cafetero) north of Cali where they visited a variety of structures made of south American bamboo species Guadua angustifolia, known as the “vegetable steel” for its impressive strength. These structures range from traditional vernacular houses, roofs and bridges designed by Simón Vélez, to classrooms designed by Andres Bappler. Russell and Lu were inspired by both the abundance and the level of sophistication found in these bamboo buildings.

1       2
Left Image: Russell (right) and Lu (left) standing in front of a huge bamboo forest near a school building construction site at UTP campus in Pereira, Colombia. Right Image: A vernacular bamboo chair in a local bar.

Visiting Cali, Colombia and the surrounding regions showed us how bamboo is deeply ingrained as a part of daily life in Colombia, from chairs and fences to larger scale bridges and buildings. Much of bamboo design is driven by designer’s and builder’s knowledge of the material properties. This knowledge has expanded over generations and has added to the scale of the structures that can now be achieved. At the Universidad Technolόgica de Pereira (UTP), an arch bridge designed by Simón Vélez (http://www.simonvelez.net/) traverses a roadway connecting two parts of the campus. He also designed the CARDER regional office. These bamboo structures are representative of emerging efforts to locally enhance the perception of bamboo as a building material. The efficient joinery techniques that incorporate mortar inserted into the poles and steel bolts, are indicative of the sophistication involved in the bamboo design.

3 View looking across the bridge deck at the Universidad Technolόgica de Pereira by Simón Vélez. The bamboo poles are covered with dark coating that protect them from sun and rain.

4 Russell (left) discussing the structural system of the arch bridge with DAGMA architect Daniel (right)


Interior Corporaciόn Autόnoma Regional de Risaralda(CARDER) where inclined bamboo poles support the roof Exterior of Corporaciόn Autόnoma Regional de Risaralda (CARDER) with structural timber and bamboo poles

Continue reading “Grow strong and live beautifully: Colombian bamboo structures”

Mass Imperfections.


The curved shapes of hand-made figurines are widespread in the Bethlehem’s tourism industry. What is intriguing about all these crafts is the precision of the forms given the basic tools used for their fabrication. An established hierarchy and apprentice curriculum maintains the artisans’ skills to a certain standard. Becoming an olive-wood master carver is, among other skills, being able to reproduce a complex-geometry shaped figurine while only looking at it.


Olive wood artisan – Credits: AAU ANASTAS

The process of fabrication of olive-wood objects in Bethlehem calls high-tech mass customization into question. Mass imperfections is a project that experiments the potential of artisanal fabrication for the construction of large-scale structures.

The project experiments the ability of craftsmanship of stepping back into the forefront of the fabrication processes. Mass imperfections challenges high tech fabrication processes by monitoring and anticipating imperfections of highly skilled artisans.

Continue reading “Mass Imperfections.”

IASS 2016: Out and about in Tokyo

Last week I had the opportunity to travel to Tokyo for the 2016 IASS Symposium, as one of the award recipients for the IASS design competition for an alternative New National Stadium. While I spent most of my time at the conference sessions, I still got to see many incredible structures while on a tour organized by IASS. Here are some highlights:

The Prada store by Herzog & de Meuron and Yakenaka Corporation features a lattice of H-sections that serves as both the lateral structural system and as the façade. img_0418img_0422

While on the tour, we got to see the Yoyogi Indoor Stadiums built for the 1964 Olympic Games. This was a very special visit, not because the 2020 Tokyo Olympic facilities were a major talking point at the conference, but because chief engineer Mamoru Kawaguchi was there to explain the project to us. At the time, Dr. Kawaguchi worked at Yoshikatsu Tsuboi’s firm, which designed the stadiums together with architect Kenzo Tange.

Continue reading “IASS 2016: Out and about in Tokyo”

Shells for the senses: the multidisciplinary success of “Stage by the Sea”

When we speak of “aesthetics”, the first sense that comes to mind is sight – when appreciating the “aesthetics” of a structure, we often refer a structure’s beauty. But a secondary definition in Merriam-Webster reminds us that aesthetics can also be defined as “appreciative of what is pleasurable of the senses.”

In Professor Adriaenssens’s words, “a formal analysis, deprived of tactile, auditory and olfactory experiences, seems only to capture to a certain extent the esthetic intent of curved surfaces.” How might structures embody acoustics and the auditory senses? Today we examine Stage by the Sea, a small concert stage in Littlehampton, England that does just that.

Image courtesy of Flanagan Lawrence Architects.

Context-driven design

The design brief first set out by Littlehampton was for a stage and a shelter to occupy its beach and “reinvigorate the town’s gentility of the early 20th century.” The project, being publicly funded, had an extremely tight budget of £100,000.

Beach view from the shelter shell of Stage by the Sea. Image courtesy of Flanagan Lawrence Architects.

Continue reading “Shells for the senses: the multidisciplinary success of “Stage by the Sea””

What I am Thinking: Architectural Fantasies with Mister Mourão

While at the 2016 International Conference on Structures and Architecture, we had the opportunity to meet Mister Mourão, a highly creative mind who describes himself as “an architect turned illustrator with a tendency for obsessive drawing.” In this interview, he shares his beginnings in drawing, his productive workflow, and his inspiration (or lack thereof).


When, what, how and why did you start drawing?

Drawing was always one of my favourite things to do. There’s something in the effort, dedication and loneliness of the work that resonates with me.

One of my first memories is being on my parents’ living room floor drawing, so I guess I started pretty early… And for some unknown reason I was obsessed with horses. That’s basically what I drew from 4 until 18 years old. Horses!


What was your formal training and how does it relate to your work now?

I studied and worked as an architect so my lexicon is deeply rooted in the city, structures and urban environments.

Basically, I learned how to design and build through architecture, and now I can distort, exaggerate and repeat all those architectural elements that make up a building or a city and rearrange them in my drawings.


What is your process?  

First I have to confess something about myself. I (obviously) love to draw but I’m quite lazy and restless, and it’s very hard for me to focus.

Continue reading “What I am Thinking: Architectural Fantasies with Mister Mourão”