Yesterday our PhD Candidate Tim Michiels was awarded the Hangai prize for his “Outstanding paper by a young talented researcher under 30” at the annual symposium of the International Association of Shell and Spatial Structures (IASS) in Hamburg. Tim presented his research titled “Parametric study of masonry shells form found for seismic loading” during the plenary session on Tuesday. Tim’s award marks the 3rd consecutive prize for the Form Finding Lab at the yearly IASS conference, after Edward Segal et al.’s Tsuboi prize in Amsterdam (2015) and the stadium competition won by Olek Niewiarowski in Tokyo (2016) last year.
Prof. Jorquera-Lucerga, Tim Michiels and Prof. Adriaenssens
Tim Michiels was awarded the 15th Hangai Prize at the IASS symposium.
Tim’s research was co-authored by Prof. Adriaenssens and Prof. Jorquera-Lucerga of the Universidad Politécnica de Cartagena. It presents a form finding approach that allows for the shape generation of masonry shells in seismic areas. There is a renewed interest in constructing these masonry shells because of their low carbon impact, spurring the need to understand how such shells should be designed in seismic areas. Earthquakes are expected to have an important impact on the behavior and thus the shape of these medium-sized shell structures, as their large horizontal forces induce large bending moments that cannot be accommodated in thin, zero-tensile strength shells. Nevertheless, currently available form finding techniques for shells, rely solely on gravity loads for the generation of their shape and do not account for seismic loading.
Therefore, the masonry shells are form-found for both vertical gravity and horizontal seismic loading so that a compression-only load path exists within the thickness of the shell. Through the application of an inverted hanging net model subjected to lateral loading in a dynamic relaxation solver, shell forms are generated for which it can be ensured that such a load path exists. It is suggested to implement the obtained forms as interconnected double-layer thin shells, so that an equilibrium thrust surface can form over a wide depth of the structure, while maintaining the construction advantages of thin-tile vaults.
The shapes discussed in this paper are the first instances of compression-only shells reported in literature, whose forms are successful and efficient in withstanding combined gravity/seismic loading. The research demonstrates how to tailor masonry shells for a resilient built environment and can be extended to the shape generation of shells constructed out of other compression-only materials such as unreinforced concrete, stone and earth. The full paper will be published in the upcoming issue of the Journal of the IASS.
On Saturday, April 29, the IABSE Future of Design 2017 conference was held in New York City. The Form Finding Lab was well represented, with Victor Charpentier in the organization, Professor Adriaenssens as a speaker and alumnus Professor Ted Segal (Hofstra University) leading a design workshop. Demi Fang ’17 summarized the main ideas of the speakers and panelists:
The Future of Design NYC conference kicked off with a vibrant set of “10 + 10 Talks,” in which structural engineers paired up with professionals in a field slightly different from their own. Each pair gave a joint presentation on their thoughts on the “future of design.”
Throughout the five presentations and the Q&A that followed, several recurring themes unfolded.
Technology can be leveraged as a tool to enhance, rather than compete with, the creative human process of design.
Glenn Bell (SGH) and Antonio Rodriguez (LERA) began with a presentation titled “Disruptive Influences as Opportunities, Not Threats.” Rodriguez gave a personal anecdote of a mentor who once warned him against entering the engineering field with the argument that computers would soon take over engineers’ work. Rodriguez explained how he has found that some engineering decisions do, and always will, require human judgment. That’s not to say that technology should be considered a competitor; rather, technology can play a key role in enhancing those creative processes that are best executed by humans.
Bell quoted Chris Wise of Expedition Engineering from a talk at the 2015 IStructE conference in Singapore: “Which bits of the engineer’s life are really human and which should we let go to machines?” Many presenters touched on the importance of this distinction, especially with the rise of digital drawing tools that easily allow for technology to “take over” the design process. Rodriguez made the distinction by identifying the processes at which computers do best, such as repetitive tasks and optimum searches. The use of these technologies “free designers to do what they do best: solving human problems.” He went on to conclude that the “future of design depends on how technology is used to enhance people’s skills, facilitate collaboration, and improve relationships.”
Soap film studies by Frei Otto
Optimization tool developed by Altair
Dutch Maritime Museum courtyard roof by Ney and Partners
Verviers Passerelle by Ney and Partners
Diffusion Choir by Hypersonic
Sky Wave by Hypersonic
This approach was whole-heartedly echoed in the following presentations. Eric Long (SOM) cited Frei Otto’s scientific explorations of soap film as an example of how “technology inspires design.” As a firsthand example, he cited SOM’s partnership with Altair in topology optimization; fittingly, his presentation partner was Luca Frattari of Altair, who emphasized the fundamental role of these technologies as tools, or “a complicated pencil.” Sigrid Adriaenssens (Princeton University) presented some of her engineering projects such as Dutch Maritime Museum courtyard roof and the Verviers Passerelle from her practicing days in the Belgian structural engineering firm Ney and Partners. With a nod to David Billington’s principles on structural art, she used these examples to note how “using optimization tools efficiently can allow for efficient, economic, and elegant systems.” Her presentation partner, Bill Washabaugh (Hypersonic), also shared stunning sculptures that utilized engineering technology to not overshadow but recreate motions of nature, such as the rippling reflection of a tree over water, the murmuring of a sea anemone, or the flight of a flock of birds.
With increased levels of collaboration in the design process, broadness and diversity in education can help prepare engineers well for future challenges.
Bell pointed out that the drive towards resource efficiency and sustainability has led to the necessity of interdisciplinary collaboration in the design process. He described his perception of the structural engineer as a T-section, with the “flange representing a broadness in education, and the stem representing a fundamental expertise in structures.” As one of the few educators presenting, Adriaenssens answered one of the last questions squeezed into the end of the Q&A session: what educational approaches should be taken to prepare the next generation for the future challenges of design, which differ greatly to the challenges of the older generation? Adriaenssens shared her conviction in bringing students with different backgrounds into the field of engineering in order to supply a diverse workforce to face these interdisciplinary challenges. “Many of the students I advise are excellent in other fields – they are superb athletes, musicians, or dancers. Asking an 18-year-old to focus on one particular field limits their potential.” She mentions courses at Princeton that bridge engineering with other fields such as the arts, explaining that “aside from the traditional engineering courses, we also need courses that focus on interdisciplinary training,” supporting Bell’s previous statements.
Guy Nordenson (Princeton University) reinforced his colleague’s comments with statements on a more specific type of diversity: “I think Sigrid is a manifestation of where we’ve come and where we’re going,” not just with her more creative and innovative approach to engineering, but also her presence as a female in the field. “Looking out at the audience, it’s great to see that there are a lot more women in the field than when Glenn and I were students. We can do a lot to improve diversity in education starting as early as high school.” Continue reading “Reflecting on the Future of Design at the IABSE conference”→
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.
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.
our CEE student in dialogue with structural designer Holger Schulze Ehring
Michael Stein (SBP) and Juan Sobrino (Pedelta) discussing our students footbridge 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.
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.
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.  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.
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.
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.
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.
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.
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.
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.
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.  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]
Philadelphia City Hall (Photo: Beyond My Ken)
King’s College Chapel (Photo: SEIER+SEIER)
Armadillo Vault (Photo: Jean-Pierre Dalbéra)
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].
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.
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.
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.
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
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.
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.
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.