ARCHITECTURE + STRUCTURAL ENGINEERING
Computational structures as form generator
During the two-week workshop on computational structures which took place at the Contemporary Architects Association in Tehran, Iran, 25 students and five teachers used Rhino/Grasshopper/Karamba to design and build a pavilion. The workshop aimed to explore the material behavior, directionality of elements, as well as understanding structural potentiality of complex geometries. Fabrication methods, as well as tools and materials, were limited due to 20 years of embargo on Iran, as the latest modern industrial machinery may be difficult to locate in Tehran.
The venue at the Contemporary Architects Association is located in a converted residential house, with an unused and empty swimming pool in the front yard. The task of the workshop participants was to design a structure covering the 4x10m pool, converting it into a vivid exhibition area. To this end, the parametric FEM program Karamba was used to aid design development, where a four-step structural analysis resulted in the final optimised design:
First step was to find an optimal shape taking into account boundary conditions of the site and the use of material. A multi-objective optimisation was performed using Octopus.e. The optimisation led to a hybrid form between a shell and a cantilever structure. The goals were to minimise the deflection of the structure under the self-weight, while maximising the projection area of the canopy. This resulted in a form of non-trivial nature, however still highly optimised concerning downwards loading.
In the second step the surface was discretised into different folding patterns to increase the stiffness by creating inertia. Comparing the structural performance of folded surfaces resulted in a structurally optimized folding methodology that was also easy to erect.
The third step was to analyse again the now folded shape under the gravity load, the utilisation of each triangular panel was obtained and translated into a differentiation of hole sizes that was cut in the middle of each pair of panels. Thus, the panels in each pair were mirrored. The triangular holes were laser cut on two sides and bend around the last, rotating the cut material upwards with varying heights reflecting the local utilisation. The directionality of the folding methodology was such that two adjacent panels’ cut material would meet and form an out-of-plane triangle.
In the fourth and final stage, a zig-zag cable pattern joined these bent triangles to form a three-dimensional tension truss. Furthermore, multiple load cases were introduced and combined with the self-weight, in order to simulate the structural behaviour under snow and wind loads. Using karamba, it was confirmed that all cables were activated – however some only under some load cases.
To avoid pre-tensioning each cable segment, a continuous cable pattern was applied connecting all out-of-plane triangle nodes, making a whole. As each node connects four cable segments, the cables were weaved in and out with a zig-zag pattern. This method also implied that the cables could be pre-stressed from the ground after the structural erection was complete. At the free edges the cable ends were hidden in a designed connection that incorporated an edge-beam.
Host: Contemporary Architects Association, Tehran, Iran
Tutors: Mariam Khademi (La Sapienza University), Mehrad Mahnia (theALLIANCE), Vahid Eshraghi (VEA Studio), Kristjan Plagborg Nielsen (Arup), Ramtin Taherian (theALLIANCE)
Workshop Team: Farhang Alipour, Soroush Asadi, Ahmadreza Atashbar Tehrani, Pouria BaniAdam, Ali Derazgisou, Paniz Farrokhsiar, Pouria Gachpazan, Faraneh Ghahremani, Hoda Hamzeh, Ehsan Heidari Zadi, Hooman Homayooni, Niloofar Imani, Mostafa Jahanmiri, Keyhan Khaki, Aryan Khalighy, Sadra Khosravan, Fatemeh Mahmoudyar, Ali Mirzadeh, Sogol Moaven, Farnaz Mohammadi, Hamid Peiro, Hasan Shafiei, Iman Shameli, Fahimeh Tahmasebian
Laser Cutter Provider: Arpa Laser Co.
CNC Sheet Metal Bending: Arpa Laser Co.
Aluminum Anodizing Service: Arpa Laser Co.
Lighting Device Provider: Shoa Industrial Group
Collaborators: Elham Razavi / CEO at Contemporary Architects Association, Ali Zolfaghari / Technical Support, Majid Kazempour / Technical Support, Afshin Koupaei / Technical Support, Mehran Davari/ Technical Support, Farshid Esmaeili / Marab Mahbod Engineering & Technical Co., Faraz Maleki / Arpa Laser Group
Cinematography and Video Director: Sepand Saedi
Photography: Sepand Saeidi, Davood MohammadHasan, Farhanf Alipour, Pouria Gachpazan