Yousef Anastas is an architect and structural engineer. He holds a Master’s in Architecture from l’Ecole d’architecture de la Ville et des Territories (2011), and a structural engineering Master’s degree from l’Ecole Nationale des Ponts et Chaussées (2014). He is currently a PhD candidate at Geometrie Structure Architecture (GSA) research lab in Paris. In 2014, he conducted a research at the Form-Finding lab of Princeton University on biomimetic building skins. He was also awarded the 40 under 40 award for young European architects. He is currently leading AAU Anastas’ research department, SCALES – a research laboratory that is consistently enhanced by linking scales that are otherwise opposed.
Recently, Anastas completed a project in Jericho, Palestine where he focused on resistance optimization of stone vaults through advanced stereotomy.
Stone as a construction material in Palestine
Historically, stone has been the most common building material in Palestine. It is abundant, and its use in construction was in fact mandated by the Ottomans in order to unify the landscape. As a result, the stone is not only a marker of the transition of urban and social structures, but also shows the evolution of Jericho’s morphology. The construction techniques’ evolution thus had an effect on the entirety of the Palestinian city.
Palestine suffers of a misuse of stone as a structural material: while it was an abundant material used for structural purposes in the past, it is now used as a cladding material only and the know-how of stone building is disappearing.
The research aims at including stone stereotomy – the processes of cutting stones – construction processes in contemporary architecture. It relies on novel computational simulation and fabrication techniques in order to present a modern stone construction technique as part of a local and global architectural language.
Our research department – SCALES – and GSA (Geometrie Structure Architecture) lab are leading this research on stone construction techniques. The results of the research will be used to build the el-Atlal artists and writers residency in Jericho. As such, Stonematters is the first module of the residency and the first built vault of our research.
Stonematters is built on an innovative construction principle allowing for unprecedented forms for such structures, born from morphology – the study of the form of objects – and stereotomy. The vault itself covers a surface of 60 m2 and spans 7 meters with a constant depth of 12 cm. The geometry follows the shape of a minimal surface on which geodesic lines are drawn and set the pattern of the interlocking stones. The whole structure is made of 300 mutually supported unique stone pieces.
Aside for the technological issues which make Stonematters a unique design, cultural barriers were also encountered; the entire project was built using existing local techniques from the culturally marginal city of Jericho. Processes from several factories were combined so as to employ known methods for new uses. Hence, the research bids at linking construction techniques to urban morphology. It puts a non-hierarchical hypothetical link between the scale of stereotomy and the scale of urban fabric. In that context, the idea is to suggest new urban morphologies linked to the scientific use of a largely available material in Palestine.
Cutting the stone
The geometry of the vault follows the shape of a minimal surface on which geodesic lines are drawn and set the pattern of the interlocking stones. Each stone has 4 inclined interfaces, that allow the assembly of the different stone voussoirs. Based on geometrical parameters as the overall shape, the density of the paving, the inclination of contact surfaces, the size of the voussoirs, and number of voussoirs types, a specific structural criteria can be improved.
In order to lay out the stones, a series of polystyrene blocks of differing heights were carved to create formwork for the stones.
These blocks of polystyrene were arranged in the form the vault was to later take shape. These blocks were placed on top of wooden framework, which was later removed with the blocks once the stones had been laid and interlocked.
While the polystyrene blocks were digitally cut using robots, the wooden framework was all constructed by local artisans using traditional methods.
Mounting the stones
Stone voussoirs are assembled on the mounted polystyrene blocks. Each stone’s location is defined on the formwork. The mounting started from the upper center of the vault progressively advanced towards the edges in a concentric process. The inclined interfaces between the stone voussoirs generate the interlocking system of the structure.
The el-Atlal structure is a model of the concept, which envisions a new construction method. The model allows for new morphologies, construction techniques and uses for a widely available construction material. The project has the ambition of creating a mode of urbanism; one whose scales are profoundly associated, one whose technique and durability leaves a trace on the city’s evolution and on the Palestinian landscape.
Author: Yousef Anastas
Editor: Emre Robe