Reporting from IASS 2017 – Severe Conditions & Disasters

Last week at the IASS the Form Finding Lab was very involved in the session on severe conditions & disasters. The session was chaired by our own Sigrid Adriaenssens and close collaborator Prof. Ruy Marcelo Pauletti from the University of Sao Paulo, and many more collaborators presented their research.

The revue of familiar faces started with Eftychia Dichorou from the University of Cambridge. Dichorou presented her work co-authored by Matthew DeJong (Cambridge University) and Giorgia Giardina (University of Bath) on the finite element modelling to predict cracking and seismic collapse of a thin masonry shell structure. Dichorou presented a quick historical overview of tile vaulting after which she focused on the impact of earthquakes on these structures. To model the effect of earthquakes, she presented a parametric study of the Droneport Project which was built last year at the Venice Biennale. She demonstrated the importance of accurately quantifying material properties of the masonry, particularly to capture its post-peak behavior, and also pointed out the need to understand the impact of geometric imperfections.

Dichorou’s presentation was aptly followed by an application of tile vaulting in Istanbul. Indeed, Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan presented their recent construction project on the Seismic design, detailing and construction of the first Catalan Vault and Domes of Istanbul. They showed how the Guastavino vaults of New York inspired them to build new brick masonry vaults during the restoration of the Hatice and Fehime Sultan Palace near the crossing of the Bosporus. They strengthened the vaults to account for earthquake loading by adding steel rebar as well as a coil steel-mesh.

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Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan showing the plans of the vaults .

Then the session shifted from masonry shells and earthquakes, to the modeling of cable net under other impact loads. Romain Boulaud from the Ecole Des Ponts ParisTech presented a sliding cable model for rockfall barrier simulations. He detailed the behavior of these flexible barriers, showing their strong nonlinear behavior (both geometric as material). These strong nonlinearities were accounted for in simulations relying on dynamic relaxation, which showed a robust, yet time-consuming solution.

Form Finding Lab PhD candidate Olek Niewiarowski then presented his Master’s thesis work on cable nets subjected to underwater loads, reminiscing about his brief tenure at Reunion Island to investigate nets used as barriers against shark attacks. Niewiarowski detailed his numerical model, and showed how the topology of nets can be impacted to better distribute the forces arising from the breaking waves.

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Olek Niewiarowski showing how to integrate breaking wave simulations.

Stefano Gabriele from the university of RomaTre got the final word and presented the work on the funicularity of shell structures he had elaborated with Giulia Tomasello (among others). Gabriele explained a new easy-to-read method to quantify whether a form-found shell structure works predominantly through membrane action, rather than through bending. The method hinges on the computation of the eccentricity (relating bending moment and normal force) in every point of the shell. The method was applied to modal stress distributions under different loading conditions, including earthquake loading.

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Prof. Gabriele explaining his new approach on how to evaluate how funicular shells are under applied loading.

The session was concluded by noting how surface structures such as shells, membranes and nets are particularly well suited to resist extreme loading.

Author: Tim Michiels

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How to form find shells that withstand earthquakes? We asked Tim Michiels who was just awarded the prestigious Hangai Prize.

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.

 

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.

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Examples of two recently constructed masonry vaults. Left: residential house in Oaxaca by Ramon Aguirre Morales (Image credit: Ramon Aguirre Morales). Right: Venice biennale droneport project by Odb, Block Research Group, Norman Foster Foundation and Redline (Image credit: Michiels)

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.

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World map overlaying seismic risk and locations with tradition of earthen construction (Image: Michiels et al., 2017).

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.

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Initial shapes for double layer shells based on a rectangular grid (Image: Michiels et al. , 2017)

Reflecting on the Future of Design at the IABSE conference

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.

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Antonio Rodriguez of LERA on distinguishing the roles of technology and humans in the future of design.

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.”

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.

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Bill Washabaugh (left) and Sigrid Adriaenssens present their projects that utilize technology as an advanced tool for imitating and perpetuating the systems and aesthetics of nature.

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”

Mass Imperfections.

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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.

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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.”

Our Summer Rammed Earth Experiment 3/3:

While we’ve completed construction on the rammed earth spiral, the project has really only just begun. Moving forward, our team is looking to properly introduce rammed earth into the Princeton community and to further research efforts by installing a sensor system to study rammed earth erosion and by building a solar-paneled roof over the spiral wall.

Community Engagement: Redefining Structures, Sustainability, and Service

Rammed earth is a uniquely sustainable, beautiful building material – and completely foreign to most people. With this project, we saw the opportunity to do more than research and focus on the idea that structures are built to interact with people. We wanted to create something that could broaden our community’s views on structures, sustainability, and service.

Working with the PACE Center for Civic Engagement, we’ve been able to expose Princeton students to rammed earth through volunteer events and service discussions. A student volunteer described how “the project had made us work together and become a single unit,” unknowingly hitting the mark on an ancient quality of earthen construction. Especially in developing areas where heavy machinery cannot be employed, earthen construction is known as a community building event. At a lunch event hosted by the PACE Center, our project incited a discussion between students from various departments about research as a form of service. We hope to hold similar events during the school year, as well as transform the Forbes Garden into a more usable space for all, where students can have class, a movie night, or just a place to relax and study.

Continue reading “Our Summer Rammed Earth Experiment 3/3:”

“Postcards From …” Series: Summer 2016

Throughout the summer, friends of the Form Finding Lab have been sending postcards from the places they have visited. The postcards are also featured on our Facebook page. For this special summer post, we’ve compiled the postcards for all to enjoy!

For the next 2 weeks we are on vacation. Stay tuned for more of our exciting posts in September!

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August 2016

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August 2016

Author: Victor Charpentier

A New Design for the Tokyo 2020 Olympic Stadium

Looking ahead, the next Olympic Games will be hosted by Tokyo in 2020. The initial Zaha Hadid design for the Tokyo National Stadium helped secure the city’s bid, but was quickly ditched due to its exorbitant cost.  After two international design competitions, Japan settled on the latticed green clad stadium by the Japanese architect Kengo Kuma.

This new stadium is far more subdued than Zaha Hadid’s and does not evoke the same awe as the National Gymnasium by Tange and Tsuboi Yoyogi.

To reflect upon and honor the structural prowess visualized in the sweeping roof lines of the Yoyogi Stadium, as well as to keep an open mind toward the future, the International Association for Shell and Spatial Structures (IASS) organized a conceptual design competition for a new national stadium in Tokyo, open to young designers under the age of 40.

The competition called for a “21st century spatial structure” on the site of the former National Olympic Stadium by Mitsuo Katayama. The competition jury, consisting of professor emeritus Hiroshi Ohmori (Nagoya University), architect Hiroshi Naito, engineer Knut Stockhusen (sbp), professor Ken’ichi Kawaguchi (University of Tokyo, Chair of the IASS2016), and engineer Bill Baker (SOM), considered the innovativeness of the concept system and the soundness of the structure.

I have the pleasure of presenting three design proposals developed and submitted by our graduate students. They all used form finding techniques in innovative ways to drive the geometries of their stadiums.

The Mountainous Gridshell entry by Mauricio Loyola and Olek Niewiarowski has been selected as one of five finalists by the competition jury, and they have been invited to present their design in September at the IASS Annual Symposium in Tokyo.

NEW LEAF STADIUM by Xiaoran Xu, Lu Lu, and Iwanicholas Cisneros (click to enlarge):

 

HANA STADIUM by Kaicong Wu, Hongshan Guo, and Isabel Morris (click to enlarge):

 

MOUNTAINOUS GRIDSHELL by Mauricio Loyola and Olek Niewiarowski (click to enlarge):

 

Author: Sigrid Adriaenssens

Our Summer Rammed Earth Experiments 2/3: Construction of swirling rammed earth wall

Before the large swirling structure in Forbes garden could be constructed, a set of tests walls were built to master the construction workflow. The tests walls will also be used to test a different set of erosion protection measures, as one of the goals of our research experiment is to assess the erosion resistance of rammed earth in New Jersey. The first test wall was built out of unstabilized earth with no erosion protection implemented for reference. The second wall was also unstabilized, but plants will be grown on top of this wall in the hope that their roots will slow down the erosion process, while their leafs protect the dirt from driving rain. The third test wall was stabilized on the outside with a 10% lime-earth mixture, which was applied only at the outer 3 cm. This technique is a traditional rammed earth construction technique originating in Spain and referred to as “calicascado” which can be freely translated as “lime shell”. The 4th and final test wall was built unstabilized earth once again again, but half of it was coated using a silicone spray, while the other half was coated with a lime wash. All of the test walls were built with a reusable plywood formwork on top of a blue stone slab..

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Scheme of the test walls
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Rammed earth test walls. Both left walls are unstabilized, the wall still in the formwork was built using the calicascado technique.

After the successful completion of the test walls, we moved on to the much larger spiraling wall inside Forbes garden. As explained in the previous blog post, the spiral consists of a lower bench area and a taller wall, separated by an opening. At its lowest point the bench is 40 centimeters high, and at its highest point it is 3 meters tall. Both rest on a blue stone foundation. Again, different erosion-protection measures were implemented. The bottom 15 cm of the entire wall was made out of a 25% lime- earth mixture, and placed on a water impermeable membrane to avoid capillary rise. The outside of the bench and most of the rest of the spiraling wall was stabilized using the calicascado technique after its promising results on the test walls. A great advantage of this technique is that it allows for a minimum volume of soil that needs to be stabilized with lime and thus requires less material transport. To compare the durability of the technique once again a section was left unprotected. Additionally, one section of the wall was entirely lime-stabilized using 6% lime as an extra test.

Continue reading “Our Summer Rammed Earth Experiments 2/3: Construction of swirling rammed earth wall”

Our Summer Rammed Earth Experiments 1/3: The Golden Spiral for Forbes Garden

Introduction

Dirt—as in clay, gravel, sand, silt, soil, loam, mud—is everywhere. The ground we walk on and grow crops in also happens to be one of the most widely used construction material worldwide. Earth does not generate CO2 emissions in its generation, transport, assembly or recycling and this in contrast to more conventional building materials such as concrete and steel. In rammed earth construction a mixture of  clay, silt, sand and gravel is compressed into a formwork to create a solid low-cost load-bearing wall. Despite the renewed architectural interest in contemporary rammed earth construction in (semi-)arid climates of the USA, little is known about its potential in the erosive humid continental climate of New Jersey. Because of the great potential of rammed earth as a local building material, we decided to design and construct a spiral rammed earth structure in Forbes Garden that will be an enduring representation of Princeton’s effort to create a campus containing sustainable and elegant zero carbon architecture.

The Material:  Dirt

The Form Finding Lab’s team established the suitability of Princeton soil for earth construction though an extensive set of laboratory tests. The team, led by PhD candidate Tim Michiels and supported by undergraduate student Amber Lin ’19 and summer intern Jacob Essig, subjected a series of compacted samples with different water contents to compression tests (the rammed earth samples had an average compressive strength of 1.35 MPa). The team also experimented with lime additives  (3%, 5%, 10%, and 25%)  to test the compacted dirt’s resistance to weathering on a series of prototype walls (See image above title).  All these results informed the design of the structure that was designed for Forbes Garden as part of the Campus as Lab Initiative .

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Testing of compacted samples with different dirt compositions to establish unconfined compressive strength. The local soil was composed of 19% gravel, 42% sand, 24% silt and 15% clay.

The Site: Princeton Garden Project

The Princeton Garden Project at Forbes College is a student led initiative that supports and advances sustainability and food awareness  on Campus. Following with its mission of sustainability, the rammed earth spiral is a sustainable experiment made with local and abundantly available materials intended to enhance the existing organic garden and transform it into a space for research and learning.

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The Garden Project, the ideal collaborator for a rammed earth project (image credit Garden Project at Forbes College)

The Design:  A Site-Specific Golden Spiral

Continue reading “Our Summer Rammed Earth Experiments 1/3: The Golden Spiral for Forbes Garden”

Learning from Japanese Structural Design: Reflections on the Symposium

MoMA’s exhibit on Japanese architecture (through July 31, 2016) examines the “constellation” of influence in the country’s early-21st-century architecture and design community, but perhaps not so explicit in the exhibit are 1) the structural engineers’ parallel relationships of influence and 2) the structural engineer’s role in collaborating with architects to produce these works. In an effort to explore these characteristics of structural engineering influence in Japan, Prof. Guy Nordenson (of Princeton University and Guy Nordenson and Associates) and Prof. John Ochsendorf (of MIT) organized a symposium, titled “Structured Lineages: Learning from Japanese Structural Design,” which brought together some of the top structural designers from both Europe and the US for discussion.

Most of the lectures presented by the guests focused on the works and experiences of specific Japanese structural designers and educators such as Yoshikatsu Tsuboi, Mamoru Kawaguchi, Masao Saitoh, Gengo Matsui, Toshihiko Kimura, and Mutsuro Sasaki. Each half of the symposium brought the speakers together for a vibrant panel discussion moderated by our Prof. Sigrid Adriaenssens and MIT’s Prof. Caitlin Mueller. The final panel discussion welcomed Prof. Sasaki himself to the mix.

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First panel discussion moderated by Prof. Adriaenssens. Left to right: Seng Kuan, Marc Mimram, Sigrid Adriaenssens, Mike Schlaich, Laurent Ney.
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Second panel discussion moderated by Prof. Mueller. Left to right: Guy Nordenson, Chikara Inamura (acting as Prof. Sasaki’s interpreter), Mutsuro Sasaki, Caitlin Mueller, Jane Wernick, Bill Baker.

Several fruitful discussions and themes arose from the independently-constructed lectures. Reflecting the literal implications of “lineages,” Prof. Seng Kuan referenced the traditional lineage model in which Japanese arts and crafts get passed down for seven or more generations. As Prof. Ochsendorf demonstrated in his lecture with the help of Chikara Inamura, such a “lineage” is visible in 19th-20th century Japanese structural engineering:

Continue reading “Learning from Japanese Structural Design: Reflections on the Symposium”