Conception and Parametric Design Workflow for a Timber Large-Spanned Reversible Grid Shell to Shelter the Archaeological Site of the Roman Shipwrecks in Pisa

Conception and Parametric Design Workflow for a Timber Large-Spanned Reversible Grid Shell to Shelter the Archaeological Site of the Roman Shipwrecks in Pisa

Corio, E. Laccone, F. Pietroni, N. Cignoni, P. Froli, M.

DESTeC, School of Engineering, University of Pisa, Pisa, Italy

ISTI, CNR, Pisa, Italy

| |
| | Citation



Reciprocal structures or nexorade are composed by the assembling of groups of three or more beams mutually connected by mono-lateral T joints in a way that any relative movement is suppressed. This kind of structures can be easily built in relatively unprepared sites, dismantled, transported and re-used even by not specialized handcraft. For these reasons, reciprocal structures have been widely used in the past for military purposes, and nowadays they seem to satisfy very well the different requirements of a quick and temporary shelter of a large archaeological area when they are shaped as grid shells.

This paper proposes the design of a reversible, reciprocal framed grid shell to shelter the archaeological site of the Roman Shipwrecks in Pisa. The structure must protect excavations and archaeologists from the weather and provide an easy access to visitors. Additionally, it must allow for easy disassembling and moving to another site.

The design choices aim at optimizing both structural efficiency and esthetical qualities. A parametric workflow for both the form finding and the digital fabrication processes has been developed, and a prototype of accommodative steel T-joint for timber reciprocal beams has been realized. Finally, a model using CNC-cutting tested the structural feasibility of such a design approach.


archeological shelters, cardan joints, digital fabrication, form finding, parametric design, reciprocal frame, reversible structures, timber grid shells


[1] Popovic Larsen, O., Reciprocal Frame Architecture, Elsevier, 2008.

[2] Tamke, M., Riiber, J. & Jungjohann, H., Generated Lamella, LIFE in: formation. On responsive information and variations in architecture, New York, ACADIA, pp. 340–347, 2010.

[3] Nabaei, S.S. & Weinand, Y., Geometrical description and structural analysis of a modu-lar timber structure. International Journal of Space Structures, 26(4), pp. 321–330, 2011.

[4] Baverel, O., Nooshin, H. & Kuroiwa, Y., Configuration processing of nexorades using genetic algorithms. Journal of the I.A.S.S, 45(2), pp. 99–108, 2004.

[5] Douthe, C. & Baverel., O., Design of reciprocal frame systems with the dynamic relax-ation method. Computers & Structures, 87(21–22), pp. 1296–1307, 2009.

[6] Kohlhammer, T. & Kotnik, T., Discrete analysis – a method to determine the internal forces of lattices. International Conference on Space Structures, London, 2011.

[7] Kohlhammer, T. & Kotnik, T., Sistemic behaviour of plane reciprocal frame structures. Structural Engineering International, 21(1), pp. 80–86, 2011.

[8] Song, P., Fu, C., Goswami, P., Jianmin Z., Mitra, N., J. & Cohen-Or, D., Reciprocal frame structures made easy. ACM Transactions on Graphics, 32(4), 2013.

[9] Rutten, D., Grasshopper: generative modeling for Rhino, Computer software, 2012, available at:

[10] McNeel, R., Rhinoceros: NURBS modeling for Windows, Computer software, 2010, available at:

[11] Preisinger, C., Karamba: parametric structural modeling, Computer software, 2011, available at:

[12] Gelez, S., Aubry, S. & Vaudeville, B., Nexorade or Reciprocal Frame System Applied to the Design and Construc on of a 850 m2 Archaeological Shelter. International Journal of Space Structures, 26(4), pp. 303–311, 2011.