Philippe Block – Stone Skins: New Masonry Shells

look working is this one okay I’ll make a brief introduction of our guest this evening dr. Philip block he’s a associate professor at ETH Zurich and we first came across Phillipe for his interesting contemporary take on graphic statics and they’ve been developing the research further and building prototypes and also structural consultancy of like historic masonry structures based on the methods that his group and like other people in in MIT have been developing and he’s also co-founder of auctioned off de Jun and block consultancy and he’s visited the DRL a couple of times for reviews and certain he’s fairly active in in academia he just came came from workshop in RM poke with the RMIT so with that I would like to invite Philippe for the lecture thanks thanks chat shaggy thanks for coming I’m pretty excited to be here and I hope I can intrigue you at least about surprising topic structures and show you what I’m doing I called it stone skills new mesh masonry shells but basically what I do is I look at the past to try to come up with interesting better or surprising ways to design things so for me it started with this building when I went to MIT actually earlier at in the in sha J’s group at the DRL I was reminded that I used to do kinetic things and all kind of what I thought was high-tech things because I saw one of my projects as a reference I went to MIT to do this kind of high-tech stuff and I ended up working on these structures I ended up realizing that they are quite high tech because I’ll just throw some numbers at you perhaps you know these these are these beautiful fan vaults at University of Cambridge at King’s College they have a span about 13 meters and they have a structural depth in the middle so these are stone slabs that are just held in compression in the middle it’s only 10 centimeters and then it goes to 15 centimeters at the end so they obviously have been standing for many years and they stand because they have a good structural form otherwise you cannot balance these stones in space like that so these numbers translated are this so this is about it this is actually exactly the thinness of these shells and so they are unreinforced so that is actually not such an obvious problem so and that is that was a problem that was thrown at me by my former adviser John ochsendorf I’ll just so first I’ll throw some introductory things at at you 2x plain where my work comes from and then I show you some examples of things that we have been doing I’ll take a few shortcuts like this one there is two very extreme ways to look at structures one is to design them for stress and material failure and the second one is actually to look at them for equilibrium and stability and then that is a geometrical problem luckily masonry falls in the second category while luckily because as you can see here with the drawing by Galileo these the problems of stress cannot be scaled while the problems of geometry can actually are scaleless that means that these Master Builders these gothic master builders are actually pretty lucky because they could just come up with proportional rules they could play with models which actually scale models on all scales to try to understand the stability of larger structures that they were building so these are actually some plaster models but they also if you look at these very intricate little vaults on side chapels and all of that these were actually in a way experiments for the need the next projects that they were doing and so they tested their ideas and

then they could scale this up because masonry is a problem of stability fundamentally and so this is a geometry problem if you’re not convinced perhaps these fuse stills from the pillars of the earth indeed the Gothic master builders used scale models to design their structures this is a very powerful thing because it’s a unique type of problem that allows us really to one-to-one scale our experiments at a small scale we don’t build models all the time so one way to visualize if something is or explain if something is stable or not is a trust line I don’t know if you know this but it’s a theoretical line that represents where the compressive forces want to go in space and then this theorem is very powerful it just says that you need to find a possible way that this structure can stand in compression if you find such a network of forces in 3d that fits within the geometry of your masonry structure then it is sufficient than you know that it will stand so what is important about this that is that actually for masonry structures the problem becomes entirely geometrical or at least fundamentally sorry I’ll still draw a few argumentation things that you hear to the left is a linear elastic finite element analysis the tools that modern engine engineers use which are very highly appropriate to deal indeed with structures that are designed for stress but these two different arches they have a very as you can appreciate a very similar colorful output but then if we look at this very simplistic trust line then we see that actually this thinner arch cannot have a compression only solution that fits within the geometry what does that tell us that tells us that if you were to dissenter this arch it would directly collapse and so it could never stand so this this is just to say that this very simplistic approach that you just have to draw a line tells you tells you quite a lot more than these elastic solutions it tells you about stability and collapse so you can only imagine what the meaning is of these kind of models apply to a lot of our heritage and unfortunately much of our heritage is being destroyed because of the use of totally inappropriate models this is a beautiful well it’s not that beautiful but this is a very clear example the Mets in New York had this beautiful tiled wall so I’ll tell you much more about his style faults later these were unreinforced tile vaults and they were replaced by a simple beam structure because the engineer in the 60s was unable to explain how these shells were standing and how safe they were the little anecdote that I needed to use jackhammers to take these shells down perhaps indicates a little bit of how well they behaved and also the pea our material of the Guastavino company that built these shells there is actually a little a little shell hidden under this gigantic pile of iron pieces I think this is fairly convincing that these shells are quite sturdy and quite redundant all right so that is maybe a bit about that at the end of the day this is the power the most powerful concept its hook hooks in version law that says as hangs a flexible line so but inverted will stand a rigid arch the idea is we all know this idea particularly through one of the masses in equilibrium Goudy the concept is is that if something hands under a certain loading condition under pure tension if you only look at static equilibrium you can flip this geometry and this geometry will be in perfect compression so this is the basis of many of these things so you could actually explain the stability of a masonry structure by making these hanging models we don’t have time for these hanging models anymore this gaudi only used a model for the colonia go well it took a highly-skilled team ten years I doubt that we can convince our clients to wait ten years to fulfill the form finding so luckily we made a few improvements for example graphic statics I don’t know if this is familiar but what’s very nice about graphic statics it’s in a way a paper version of of a hanging model and it uses these diagrams that represents the

equilibrium in a hanging system in detail were used extensively to explain masonry this is under different loading cases some people tried in 3d but being stuck with the 2d drafting plane this became very quickly very tedious to use for me it started with this book at MIT a beautiful book by William Wolff if you want to learn anything about graphic statics I recommend this he basically looked at a 3d structure by slicing it up into the arches but as you can see it was 42 years ago that anyone opened his book at MIT so either I was doing something revolutionary or my research was totally obsolete well at least I got a job out of it so then I push this graphic statics and I extended this to 3d this is just to give you a mental image I will not go in too much detail but everything that I will show is actually based on this what you see is that just with 2d diagrams this is a layout or a decision of of where forces go this is a diagram that explains the equilibrium of the structure and from that we can very easily compute a compression-only network of forces and how it works is that if the equilibrium of every node in the system is represented by a closed vector polygon of forces in the other so you see that that it’s not only covering local equilibrium but also global equilibrium so the power of these diagrams and this is a direct extension of graphic statics is that you have at the same time an explicit and direct representation of both the form the geometry of where the forces are for flowing and the forces and you can directly manipulate these and steer them to control your design how can you do this let’s look at a very simple node so here if this node has equal amount of forces remember these diagrams are vector equilibrium forces so this is equal in all directions you get a symmetrical structure if you attract force in one direction then your structure becomes more shallow this sounds may be totally confusing it probably doesn’t if you think of the opposite for the same set of loads if you have a hanging chain if you have a very deep structure for the same load you don’t have to pull much so it doesn’t have a lot of horizontal pull for the same load if you want to make this structure a very shallow you need to pull much much more so if you do the inverse and you control this you steer this yourself as this then you can decide to attract more force in one direction and so you make the structure more shallow in that direction so this just for those of you who use kangaroo in grasshopper or who use some processing or some particle Springs the difference with this is that you here explicitly decide it’s a design decision to redistribute the forces rather than just having a hanging net find a unique solution for the parameters that you gave it all right so this is then the first thing that we have for a certain layout of where forces go if it’s equally distributed to forces then it’s some sort of a symmetrical pillow-like geometry if you attract forces so longer lengths means more force attraction then you get this bad shape because indeed your structure becomes more shallow in this direction if you do this asymmetrically then you get an asymmetric shape and so on and so on so this explicit control really allows the designer with very simple diagrams to redistribute the forces and directly see what the replication is in 3d all right but with this kind of forward approach this is perhaps the start of something exciting you cannot explain these kind of complex geometries again this is another beautiful example in Lisbon the Geronimo’s Cathedral monastery and these geometries only have 10 centimeters and a very specific only a very specific compression only solution can explain how they stand again this this is maybe a little bit too detailed but you can just by formulating this problem and taking all these degrees of freedom you can find exactly the balance of all the forces in the system that map perfectly to the middle surface of this geometry and so this here this five diagram actually represents a compression-only network of forces that fits exactly in the geometry and then here this abstract diagram is actually a representation of all the horizontal trusts so all the horizontal forces in the system so all

these little archers need to be balanced in this very specific distribution of forces to get there so you can I hope you appreciate that if you were to do this with a hanging model you might need to do a few iterations to get to exactly the specific equilibrium all right and then just to show that this these things are being used in practice I’m pretty proud that we saved for Jefferson from the client wanted to wrap it in a steel cage because it was the client plus the engineer were convinced that it was going to collapse because a few stones fell off but then we showed with our 3d tools that actually there was nothing at all and in fact we signed that this structure will be safe for the next 500 years that this may be a little bit bold but that is at least it will not get these ugly blue braces for the rest of its life okay but what is the point so a little bit of build up was to say that unreinforced masonry historic masonry needs a good structural form otherwise it will collapse but then if you fully control all the degrees of freedom then you can start to design new efficient and expressive structural form so for this we implemented some of these ideas in a simple tool it’s called rhino vault it’s available for free we have thrown it for example Roger and his team at Saadat architects have played with this it was quite remarkable to see our architecture in compression-only within half an hour so that was kind of cool to see so the thing with this tool is that it’s it’s implemented such that it is one that it is dummy proof and two that you can really indeed explicitly redistribute the forces and then see what the result is so here for example you attract the forces such woops sorry I hope you can imagine then what will happen because you attract forces you get this little crease of or this little undulation in the geometry so it also makes you appreciate actually that’s almost anything is possible there is no such thing as freeform anymore if you properly support your shells but it tells you directly at what cost so it shows you the proportion of the forces and it shows you what you need to do to get to certain geometries so here if we start from a shell a compression shell inspired by the British Museum which is not a compression shell at all but if you start from this geometry and you start to again redistribute the forces attract them differently like such then you could see that maybe Chris Williams could have spiked up the design by Foster’s a little bit by making some little bumps and by making it asymmetrically so this this can be directly and quickly done just by again attracting the forces differently and then the last example of this tool so all these things this is in real time and this is a slow version here this is a little geometry a little example inspired by stuttgart21 I don’t know if you know about this project but Rio – beautifully designed it is very efficient shells but then the engineers in Stuttgart decided that it’s needed to be reinforced heavily so this is done showing that Fry was maybe not that wrong after all but anyway alright so this is done Matthias and Lauren’s two of my PhD students developed this tool and this was done in about five minutes so this could be built in compression only which means it could be built in unreinforced masonry for example okay but let’s go to some examples these are the three ways that one could span masonry span space in masonry a European tradition on full formwork this is Nubian faulting and the Mexico in Mexico they have some nice new evolutions there and then here the third one is a tile vaulting the nice thing about the two last examples is that they don’t need any formwork so they can be built in space alright so this is how tile vaulting goes using a faceting mortar you just built in stable sections in between the boundary conditions you do this in multiple layers with a faceting mortar and then you can build up these shells so there is a lot of examples in the United States like this is at the Bronx Zoo this is actually the home of

the elephants this may be you’ve seen this at Grand Central Station actually if you look up it’s at many many important buildings for example the Boston Public Library also and you use you recognize these style patterns this is not decoration this is actually the structure itself so these shells spend almost 20 meters with just 15 centimeters of basically floor tiles right and so they’re built also on top of that they’re built in space another example they are now being are really really she ated these shells for me desert sensational these are spiral staircases again built in space with faceting mortar and no reinforcement so this structure is standing without any reinforcement and you see here happily standing with a lot of weight now using this approach that I just threw at you a couple of minutes ago if you look if you choose a logical forces that would represent the equilibrium of a dome which means arch action to the supports and then hoop forces so a dome with an oculus so that is what you see here you have arch is going there and hoop forces in the other direction if you flatten this dome the only thing that changes is that the horizontal trust becomes much much higher because the structure is much more shallow remember we the relationship between a deep structure has a small horizontal trust and then exactly the same structure but shallow has much more horizontal trust imagine now that you cut open this dome and you peel it open then you still have the arch action going to the supports but now the hoop forces instead of being balanced in the horizontal equilibrium they now curl into 3d and this is made clear because actually the force diagram is exactly the same so that is the value of using having this explicit control that you can now explain why this tin shell spiraling staircases can be just standing there without any steel or any other means of taking bending no surprise the Guastavino is extensively used graphic statics to design their domes and if you’re interested in any of this more John well this is he should give me a percentage because this appears in all my lectures but it is really a cool book and it’s a it’s basically from for free on Amazon okay so this this is what the Guastavino did for me the first time that I encountered these vaulting is here this was the master mark project by Michael Ramage he is here he is now a lecturer at University of Cambridge and he built its little shelf Ernst Matthew T’s is being interested in it people found out that Michael and his advisor John ochsendorf were shale builders and they asked them to build a shell in Dover they said yes we can do it so then the second shell that Micah built was this one it is spanning 13 metres it’s again unreinforced only 15 centimeters thick and it’s it’s using only local materials so John is was my advisor he also is my partner in our little humble consultancy but we have a little bit of a healthy competition going on so I wanted to do things a little bit better than him so at ETH I said okay let’s try to do something better so we worked on this shell the idea was to showcase our tools so here we used Rhino vault to redistribute forces the as I said one of the main advantages of Catalan vaulting is that you can build in space without formwork but in this case because we have a very specific 3d geometry very precise 3d geometry we ran out of time and we use this cardboard guide work to trace this geometry so we quickly use some scripts to generate these boxes and then we could build out our shell in space because these cardboard boxes can actually take a significant amount of load we could actually cheat a little bit instead of always just staying in equilibrium in the in-between stages which we could we could use the guide work also as somehow as formwork so this was to express some more flowing patterns that express a three-dimensional nature of the show then very convenient I had a little Mason Lara Davies on my team so she spent five weeks of suffering building this show we took the information of the structural diagram to embed in between

the different layers on structural ribs in typical Catalan vaulting you built the ribs first and then you patch up in between but this didn’t make sense here because we had a fully 3d solution so we didn’t have these pronounced arches so we didn’t want to express this either so here we see some images and what’s nice is that you can have directly the information of where the forces are attracted so where you want to embed these ribs so this was of course taken from Candela who also has this hidden thickened ribs in his structures some different end conditions and then this is these are these five weeks of suffering by Lara and there we were one thing because we were cheating the guide work was also somehow phone work a very important thing when you build such a funicular a compression-only shell it is designed for a dominant loading and it is not happy at all with point loads or very heavy asymmetric loads and if you D Center your formwork asymmetrically it is actually exactly the same as loading it heavily asymmetrically so we needed to make sure that we had a D centering mechanism that makes sense so we work we worked on a very sophisticated system this is a spacer dry this is a spacer wet so this was tested with some flowerpots and then we were convinced that this system would work so we put the entire scaffolding onto all these little cardboard spacers they were all in tubes for the for the full six weeks that the formwork was standing at the end of the six weeks we cut open all the tubes we poured the water water in it and lo and behold everything came down at the same time which was a very pleasant surprise so we could safely dissenter it and this was the end of the first prototype that we did just to show hopefully you agree some geometries that might surprise certain people that this stands in compression I enjoyed the heated discussions with my colleagues in civil engineering that insisted because this was anti clastic which means negative negatively double curved that there had to be tension all over here but this is somehow a little bit hard to do because these are just plastered together masonry tiles and then by the way you might have noticed that I skipped over this quickly one big disadvantage of having this full guide work is that you could not clean up the the seams while doing it so this would not need to be taken care of in a second stage but Lara had to fly out to India so we lost her and no one else was motivated to clean this thing up so this was it as probably you can imagine we had no building permit for this thing so ETH emo billion was getting a little bit nervous about this strange structure that attracted all kinds of kids in the weekend so we used our tools to try to see how much load this structure could be but we would not take ourselves serious as master builders if we didn’t do a ghetto load test ourselves so this is a very Swiss precise loading condition here this is actually three tons of weight exactly at one point load my colleagues in engineering thought that this was a great case to do to use their new fiber optic sensors to measure the collapse I was also hoping for an educational movie but nothing happened except for this this tower collapsing onto the vault and still nothing happened so it had to go this is matthias he programmed typically so this was a very exciting day keep going keep good so you see actually how sturdy this that is of course that all the forces need to go through this leg so we by the way we thought that this little thing would already do something okay this is a little bit surprising it stands in cantilever the reason for this is of course the scale of the fault that there is some bending capacity if you blow this up this would not be true if you don’t believe me the next project I hope I will convince you that this is the case again you see how sturdy these things are so it is not only religion

man it is not only cool to destroy things but it also makes you appreciate that nice and good double curvature makes it very redundant and sturdy a very redundant and sturdy system this is Tom my overly excited postdoc and then very appropriate some some physical project to see plane for those of you who use right now alright then this was the expression of a smooth geometry then last October with Dave diagram of super maneuver I did a design-build workshop at UTS in Sydney and the challenge was to explore a ripped Catalan vault with the students and they got introduced to all of that to the tools to masonry to structures because they actually don’t have a structures class at UTS and they built all of this in ten days so we created this full formwork for the ribs then we built the ribs with a high structural depth so that they could stand by themselves and then afterwards we could then patch up the the parts so this was another expression another possibility of trying to do something new with Catalan vaulting instead of having these linear arches that you patch up now because we have the phone finding tools you can have these networks of interacting ribs that then are stable and that you can patch up afterwards alright so we already covered that unreinforced masonry needs a good structural form it will collapse otherwise but then if you actually know other forces are going then you can design with very little or very low quality material an example for this is this project perhaps some of you know it in mapo-gu by peter rich the structural designers were John ochsendorf and Michael Ramage and I did the structure analysis for these vaults the idea here is that basically these vaults are using salt press tiles bit only 8% cementing it to stabilize them they were done with manual labour and they were done by the local community that is because it was a poverty relief program the site is very distant so it didn’t make sense to fly in any material so everything needed to be done with local skills and local labor so here we see Michael explaining what will happen these people were until a week before that there were farmers or carpenters this is by the way James Bellamy the master mason from New Zealand that we sent for all these projects and here you see that they were not quite convinced yet what the white folks were telling them to do when they built our first little shell but then this is one week later so this is typical Catalan faulting so here you first built on full form of the arches this is actually not for work this is just guide work but because we are working with very low skilled laborers basically they have non no skill in masonry the week before this it is important to trace the geometry very carefully because this is just dirt soil you need to then waterproof the structure very carefully so that will be the black next layer and then on top of that for architectural reasons there is these stones this was to blend in better into the landscape but actually it is also very meaningful for structural reasons because by having these very heavy loads it makes the dominant self weight even more dominant and so it means that the shape that the structure was this was designed for Stace more happy during its lifetime because you have this very heavy weight so live loads would have less of an impact an additional thing sorry what’s really nice with these projects I have done now a few I’ll show you the next one in Ethiopia is that it’s great to the the pride and that people take in the new skills and these new structures here look how thin you can go just a little detail about these styles they’re actually so weak in bending they’re about 25 centimeters that if you hold them on one side they’re just breaking bending so that’s why it’s very important to stay nice in compression but you see this can be soaked in if you know exactly where the forces are going you built in space and these are the larger vaults that have a span of almost 20 meters so here you see for some scale

these are basically just dirt held in space because they follow exactly where the compression forces want to go you can do floor systems without needing any reinforcement steel because the permanent shell is always nice in compression and if you use local materials and it nicely blends in this image for me was important because when you talk to people over there they’re sick of Westerners coming with cheap solutions that look cheap and they ask me what you want to live in what you propose and when I see these images I typically answer healthier because I think these things are fairly elegant even though they are literally dirty and then here the floor system if you have a very shallow vault of course it trusts a lot so these you need is tension ties to help the edge beams to relieve the edge beams but they can then be integrated as lighting fixtures and all that okay and then we translated this to Ethiopian this is how the so called low-cost housing is done you see there wastes a lot of material for the woods need to import everything because they don’t have precision team performer they don’t have reinforcements still they don’t have cement so basically it’s a very high cost to mimic our Western building paradigms so together with the ADIZ abeba University the Institute the Ethiopian Institute of architecture building construction and city development we started to work on a prototype to train the people on these new techniques to do some workshops at the university to train people on all levels on the vocational training the architecture the building planners the engineers an important thing to say about this disclaimer is that as it also doesn’t make sense to build unreinforced in regions of high seismicity it is also important to know and understand the quality of the materials of the soils that you can use so we work together with cata experts in earth construction to teach people how to assess soil locally on the field but then also how to do laboratory tests and then we built this prototype the sustainable urban dwelling unit also called pseudo important for me was which the South African project was a very expressive project it was a highly engineered project it was a highly controlled project and that was for a museum and for another purpose here we wanted to come up with a model that was that could be safely copied so during construction we all always had this hanging chain hanging there and the hanging chain was basically used to form the geometry of the vault so here it is an advantage of having just a single curvature vault is that you can describe it just with straight lines and then build it in space so here Lara is teaching local people that we found outside of the doors at the University they actually heard that something exciting was going on and good for them because now they’re being sent as teachers to different parts in Ethiopia so here the floor system with some stiffeners these stiffeners are then filled with the stabilized soil and this then becomes the floor then these are some last images this was with my colleague death cable and as I said important to have a safe technology transfer this exactly where this shape come comes from always as a reference okay then for the top floor of the shell we were inspired by this Nubian vaults in Mexico they go a little bit harder and do these beautiful structures this is how it works because you have them leaning against the corner you built in stable arches you use a lighter brick you can just again build without any formwork so this is a very efficient technique but much more constraining when it comes to the shapes compared to the Catalan vaulting and then in Mexico they do these kind of shapes and if you really master the techniques you can get in compression-only built without any form work quite some interesting shapes going so that is what we use them for the top floor because this one is exposed to the elements we needed some good double curvature and we didn’t need to save on the structural depth of the floor system to push the prototype a little bit more we wanted to waterproof it also in natural means and so we got introduced to this cactus waterproofing this is basically fermented cactus the anak discounts from Mexico this is basically one step before tequila something equivalent and apparently how this came about is that they were making

their there their alcohol perhaps drinking alcohol while making their alcohol they poured or for this mix and they saw that from that point onwards the floor was impairment though and so they started cleaning this on the buildings to waterproof that so that is what we did so this is the result it looks very boxy and boring that is exactly the point because this is a building that is 90% local soil and still looks like a boring concrete box which are Ethiopian colleagues insisted that this is a sign of modern living and a modern construction but then still with some nice in from the inside of the techniques that were used after the South Africa project we were invited John and and I to do a little into installation for the design triennial at the cooper-hewitt so we decided to give a little twist about local materials and this is a fault because the tiles are made out of sheet bricks which means that they’re 100% post-consumer we waste of which 30% actually we well cleaned up raw sewage we thought that this was appropriate to put in this exhibition to build for the other 90 and it was particularly appropriate next to all these shiny objects but basically anything you can compact you can then start stacking and building all right let’s then maybe go to the the applications that I find most interesting the ones on full foam work the first model that we made was actually such an application here this diagram is maybe important to look at you see that there is a lot of force being attracted in the back edge this is the model it’s the smallest thing I made but it’s a 3d printed little thing and it stands without any glue just in compression with certain zones of only 2 millimeters if you wonder how we made this we have this nice puddle puzzle with this cake form that we flip then you have the horizontal restrains on the sides so that it can trust and really work in 3d then you can flip it and there it stands and then to show that we are indeed not cheating that there is no glue involved this little maybe you notice it’s a black colored individual it’s again Mattias he likes drama so but it’s this these models are actually very useful because they really sense where the forces are going and you also appreciate how much redundancy there is remember there was most of the force in the back art so that is now stabilizing the the other half of the structure here another thing about masonry structures is there are typically fairly deep so you can imagine different force paths that actually stabilize this structure until too much abuse we use this also to calibrate new tools this we do in our if you come and visit us at ETH maybe the robots of Yama Sakura are a little bit more well-known than our little lab that we are now hiding the robots behind so you will see our lab before you see they’re flashy robots right and so we do we have a testing table to relate the differential settlements of the supports to 3d collapse okay but if we want to build these structures these these volumetric structures a big challenge is sterile to me how to cut up this geometry so here for this nicely sophisticated shapes this is Westminster Abbey here right you see that there is a nice logic of how they’re being cut up and this logic also has to do with the logic of the force flow in the structure this is how they did it in those days we might be a little bit further along but the key thing is that if you have more freeform looking geometries that more from one geometry to the other the key thing is that you want all the interfaces to be as perpendicular as possible to the flow of forces to avoid sliding failure and all of that so that it’s nicely locked into place so we have these little these little tools that allow us to do this so here for example you can project patterns and then it constantly takes the structural flow of forces into accounts this is this is all ok and all the phases are aligned as close as possible to be perpendicular to avoid sliding failures because we are designers we also want to be able to drown the fly and to lay out these patterns this is also actually also an excuse because you can imagine if you more from different geometries you have these tough singularities in between two things coming together and it’s always

easier as human being to negotiate and mediate between all these things instead of touring it into an algorithm the master-builders would not build our stuff like this this is about the most inefficient way to deal with stone it is very time-consuming very expensive it just really silly so because I’m building up to actually this is we are doing this research because we actually have a real project that will be built like this we had to look into more efficient stone cutting machines techniques for example with these large blade cells that come in with multiple axes or these wire cells these are diamond encrusted so this is basically a hot wire cutter for adults right and if you look at these 3d geometries then you can nicely approximate them with ruled surfaces we thought that this was a solution so we made a little CNC controlled wire cutter instead of using robotic arms that moves foam stuff in space we didn’t want to go to that why because these degrees of freedom are exactly the same degrees of freedom of exact existing stone cutting machines and so we were as we were commissioned to advise on the client and a stone fabricator to choose the machine that we needed so we did this test because these very sophisticated there is even versions with nine axis of control of these wire cutters but they don’t have any software to control them so we had to sketch up a software to then control this wire cutter so this software approximated the the arbitrary geometry into the closest fit rule surface and then designed to lead in lead out paths to Dan Curtis of course in real stonemasonry you would not cut away the top part it would collapse it would crash the the wire or collapse on the rest of the stone but again you will see that person dressed in black Mattias will appear and he’ll eat he likes a little bit of drama so here is with unfailing and indeed the piece was always in it so in this piece we also embedded these this registration these notches that he interfaces this is important because if you built it in real scale the problem of registration and the accumulation of 3d tolerances is very important so you need to have these shapes that naturally fit into each other so okay this seemed like the solution but then we contacted the Constructors and in reality because the wire is bowing so much you can actually only have a tolerance of even only 5 centimeters so that was not sufficient at all and the reason is is that these wire cutters are extremely efficient when you cut straight and so they are typically used for rough cutting and then there have been made more precise with some CNC machines so this collaboration with Escovedo construction started four years ago this is for a vaulted multi-purpose thing in Texas in Austin Texas the main span is 30 meters this is an initial design sketched as many of the architectural features missing but the idea is that this is cut stone so every piece is different unreinforced and on top of that dry stone so we said that already sorry so no mortar used so that is why we could not use these wire cutters we needed to go to much more precise techniques this shell was actually designed with a free plugin maybe we have some tricks up our sleeves internally but it is exactly the same it’s Rhyno fault and what I’m showing here is that if you have a typical hanging shape where you have no control of the geometry this might be the force distribution but then this tool allows you to explicitly redistribute the forces the proportional distribution of forces to get to certain effects so for example here what we did at the ends now these flaring edges because we wanted to have a geometry that is not the typical funicular gardius kind of obvious funicular shape but we wanted to have these these features that perhaps are more surprising for unreinforced masonry then we took the force flow to tessellate so here all these faces are as perpendicular as possible and the dovetail geometry is to have this natural interlocking system once you assemble them but then now this

is when it gets fun we I had to MIT interns for the summer which is great so I had some little vaulting little vaulting construction slaves and the little dots are actually just registration because these were 800 pieces we could test some these centering logics and then there it is standing so this is again standing without any glue for those of you who were maybe in the did room of the Venice Biennale you might have noticed if you pushed if you had pushed this model that it was glued that was because we indeed expect that people would be curious and it would have been a pity that the first visitor would have collapsed our structural model so this is actually a real structural model because as I set in the beginning these scale models work principally the same as a large scale we wanted to have all these specific features like this is the typical i opening of Rio tow but this is known of course for tension structures not at all for compression structures the flaring edges at the ends is an homage to the famous shell builder Heinz easier again in a very different material this is in reinforced concrete so here these these edges that flare up and this is possible due to a very careful redistribution of forces okay but then to show that we were indeed not cheating and not losing the model after the first visitor as I said we included this video this don’t worry this is kind of a Godzilla jumping exactly on the edge this is very unlikely to happen but we wanted to again show and feel and sense where the forces are going and then also have this nice high-speed collapse things the client asked me to send this movie for purposes of clarifying to the City Council in Austin what is happening but he asked to maybe omit this part because he he had a feeling that they would get a little bit nervous seeing this this is done a horizontal acceleration test so actually now the plate is put on on rollers and so there is a heavy horizontal acceleration luckily everything is bigger in Texas so are the foundations it seems because there is 0.000001 percent chance of an earthquake and so this might also not happen now this will not happen and yeah so now doing the numbers with stone fabricated this is about eight eight hundred pieces this would mean that their machines would be running for three and a half years just cutting all the stones that is a little bit ridiculous so we will reduce the sizes to the maximum size possible in stone and so the slats will be two meters by three meters and then a thickness of 30 centimeters to a meter 20 and then MFI is our client in Texas who has been extremely nice to give us a total caster blush to just the only demand was make something as sensational as possible so that is a very nice client to have and then this is where it was alright but then another challenge is to use this machine so it’s all nice and a nice academic exercise to have an entire structurally informed fabrication aware digital design process the real challenge is if you really need to build these things so for this Mattias went for three weeks to Escobedo construction to look at the strategies of cutting so these are the sequences first you do the outside geometry you leave these pieces out what’s important about that is that the registration of the piece that is needed to flip it over to have the other side is entirely precise precise because it’s controlled by the CNC so you don’t count on this top surface to be flat because the depth of these grooves exactly identify why the where the part is so you cannot be more precise so this is then what you do on this side and you flip it over on some brackets then you did the other side and then you cut that and at the end you can cut it off and the last part is being manually removed so what’s nice then is that I’ve been working with Escovedo construction for the last four years so they trust me in extension they trust Matthias so he was allowed to hack their 1 million dollar machine that they bought for this

project and then to write the D on code his own code to simulate the speed and the most efficient way to cut the stone to check that you don’t either kill anyone or bump into something while turning around and while cutting again the reason that you have to write these things yourself it is because the main clients that I have our kitchen table tops and grave tomb stones and things like that so you don’t need these kind of strategies but because there was a logic of similar pieces into the geometry we could optimize this and customize or cutting strategies so these are the very first pieces that are being built built at a third of the scale we’re using Texas well how is it called cream Texas cream this is a soft limestone the reason for this is that because we go dry we don’t have any mortar to distribute the stresses if you have any imperfection at the interface they will just be crushed and so it’s also easier to cut so you this big blade saw so it has a bed of 50 meters by 10 meters here and then the blade saw has a diameter of 2 meters but this is a small version that is mounted alright so this project makes me nervous it is a really great opportunity I can design a design it together with my team I am on top of that the engineer and they put me on the board of the construction company that will build it so that is pretty cool but it will be built and you can imagine that there is still a lot of challenges that we need to solve for example how will we build this this formwork so there we are working together with Peri systems in Munich that also did for example the Mannheim grid shell by FRA auto or did the paper undulating pavilion by Shigeru bum in in the Hannover in Hannover yes I think so and so they are convinced that they can do it but so these are big questions that we still need to solve because as I said if we don’t dissenter this vault at the same time it’s the same as heavily loading it asymmetrically and so we might get some challenges the client insists that I say instead of if this gets built when this gets built so I hope that in a year of – I can come back and share you hopefully great great successes of this thing are standing in space rent so here we are the first three pieces of this shell standing okay so this to wrap up I started by looking at historic structures and then what I try to show you in this lecture is that even by learning indeed from these master builders by understanding how these structures work that even literally for masonry you can already apply in very different applications you can create some new forms this is a very low-tech construction and low-tech design application high-tech design it’s a it’s a sophisticated 3d form but it’s low type construction and there is not taking low tech about this structure so I’ve tried to show you a range of projects but what’s important though is that we I stick to masonry because it’s the most dramatic vehicle to basically show that our digital tools are not achieved that they really work because as you saw with the structural models if it doesn’t have the good geometry it will collapse on you directly and so in that sense it is good structural form geometry this kind of hint that a lot of almost free for more blobby looking things can be possible if you know how to support your shell and how to redistribute the forces this is true for any material and just to give you a hint this is a project that we did with SWAT engines by architects my PhD student Diedrich vane and I’ll do this this is for a landscape bridge this would be a tin shell the local engineer suggested that we needed these big beams this is going back 60 years in time because this is not necessary at all so luckily Dirac went with a second opinion and brought a very convincing structural model this is a pre no keeping 250 times its self weight in a very unfortunate loading condition just to say that there

is something to be said about efficient shells but one issue of course of shells is that they’re very expensive to make cam Dena had this very elegant solution of these rule surfaces the high parts could be built with straight elements for the formwork but you still see how much material is needed to construct this formwork also very labor-intensive this is the example of the rolex Center by sana at EPFL and this was a very precise and very expensive form for for market system as well so the concept here is to use a mixed cable net fabric formwork system that basically we developed algorithms that allows you to pre-stress all the cables such that you can approximate almost any target geometry that you give that is globally anti clastic probably double curved why can we do this because it’s exactly the opposite of the masonry problem there we need to be in pure compression here we need to be in pure attention and so it’s the same idea but then we apply it differently and so this would then be a way to build these large-scale structures I’m now working on a project I’ve been fortunate to I’ll build one of these things in Zurich for an apartment building not not building we do one unit in this building and we will employ this system to basically generate the roof so what I do is I learn from the past to design a better future that’s maybe a little bit of a cocky statement but I just want to stay with we say with this is that I really believe that that we can learn a lot from the old master builders there is a lot of knowledge that is lost remember the first image that I showed you these thin shells shall masonry structures that are only ten centimeters as thin as an eggshell that are spanning 13 meters not many modern engineers would there is many reasons for this like liability we have other liabilities than in those days but not many engineers would be feel comfortably enough to sign off on these kind of structures this just as an indication that is master builders really did sensational things and if you really understand these structures better I think we can really do some exciting things this is not only true for Mason but as I said if you understand masonry as a most dramatic vehicle you can really tackle any material well that’s it thanks a lot for your attention I’m happy to take further questions I see that I filled my entire hour because my plan was like look at the clock at what time it is but it is totally dark here so I had no idea what time it was so thank you for still being here and I’m very happy to take questions a very very inspirational lecture appreciate it I had a question on the the tectonics of the Austin project in creating the the toolpath sort of mechanism there are you coordinating the tool paths of the masonry as like an ornamental feature on the on the masonry blocks how is that incorporating that that that could be an option it will depend actually on even though we got CAFTA Blanche I am committed to make it as efficient as possible and so it’s and together with a client we are committed to showcase a project that pushes all the efficiencies even though it is crazy stone and all of that and it uses a lot of technology so it will actually depend on what is the trade-off so if it is feasible to do the tool path to express some flowing patterns and things like that it’s not an extreme expense then we really would like to include this because it’s a performance area also acoustical issues will come into play so it might well be that a pattern so this we still need to examine further that a parent is actually triggered by the acoustical needs to have a diffusing pattern rather than a smooth one and so this this will depend and these are still some questions yeah I would say in general don’t do it

it’s kind of silly yeah okay good point I was going to use another example the higher Sophia actually is also still standing it did collapse partially once and had to be rebuilt and is still standing but the Mexico example is quite remarkable and you saw maybe how hard it was to destroy our shell that only had two layers it is because it has a nice double curvature the same actually for the shells the project that I showed by alfonso ramirez sponsor a friend of mine he insisted I call him his friend but he’s 74 years old so it’s a bit awkward but but these are amazing shells and they’re all still standing they all survived this heavy earthquake in 85 or 86 that any engineering school uses as an example of how to deal with earthquakes and the reason for this is most likely that on top of the the inherent that this is designed for a dominant loading case the nice double curvature makes them very robust and very redundant how can you look at this that is if you have something that is seen clastic so positively double curved you can imagine for any loading case you can imagine a lot of load paths that can go to the supports so the thing is is that that is one way to explain why these shells are so stiff because there is many load times that you can imagine but still I would not necessarily push your luck by now building new structures in such zones as a background actually the project in Ethiopia is in a moderately seismic zone and I forgot to point out that actually in the structure there is embedded that is why it’s 90 percent soil and sorry local materials and not 100 percent there is actually a rigid frame embedded to take the lateral plus in between the layer there is there are some five fibers embedded just to add some ductility to the structure so that there is no sudden collapse so these kind of things there these are the few things that you can do but in general you don’t want to build in seismic regions but you’re quite right that in Mexico they’re still standing which is remarkable the same by the way for these thin concrete shells and all of that actually Shahji your shells are still standing right in in Mexico and there was a mild earthquake first of all thank you for your lecture really inspiring could you use some tension force to actually counterbalance a quick situation like I imagine you don’t want any attention but can you embed in your system some tension cables that could come into place whenever earthquake keeps in shape could actually ground it well actually this is this is being used in retrofits of historic structures actually more responsible retrofits where they don’t start drilling routes into it or wrap it in full carbon fiber exactly what you’re saying is that they wrap it with somehow a net that catches the vault as soon as it wants to collapse so basically it doesn’t allow the the arch so if you imagine there is a seismic event that the arch starts to rock and basically what they do is they wrap it they don’t glue it on it because this is destructive but they basically just offset make a tension zone so that if the vault wants to start it cannot because it’s constrained by this element so that is maybe not exactly what you said but that is a more more appropriate technique that is lately being developed to to make sure that our heritage our heritage is not collapsing under heavy seismic conditions yeah yeah and then the other thing is just the embedding of fibers to make it but that is more a secondary and thinking that even Candela had some tension wires in these structures yeah yeah of course yeah but these are these are anti clastic shapes that count on compression main compression in one direction and the stiffening comes from tension in the other direction so there you need to you need to have these elements all right but not too many people left

so thanks a lot for still being here and I appreciate the invitation and yeah anyway my name is Bloch I play with blocks so you can easily find me on the web