The goal of this paper is to derive a structure preserving integrator for geometrically exact beam dynamics, by using a Lie group variational integrator. Both spatial and temporal discretization are implemented in a geometry preserving manner. The resulting scheme preserves both the discrete momentum maps and symplectic structures, and exhibits almost-perfect energy conservation. Comparisons with existing numerical schemes are provided and the convergence behavior is analyzed numerically.

Automatic joinery has become a common technique for the jointing of beams in timber framing and roofing. It has revived traditional, integrated joints such as mortise and tenon connections. Similarly, but only recently, the automatic fabrication of traditional cabinetmaking joints has been introduced for the assembly of timber panel shell structures. First prototypes have used such integrated joints for the alignment and assembly of components, while additional adhesive bonding was used for the load-bearing connection. However, glued joints cannot be assembled on site, which results in several design constraints.In this paper, we propose the use of dovetail joints without adhesive bonding, on the case study of a timber folded plate structure. Through their single-degree-offreedom (1DOF) geometry, these joints block the relative movement of two parts in all but one direction. This presents the opportunity for an interlocking connection of plates, as well as a challenge for the assembly of folded plate shells, where multiple non-parallel edges per plate must be jointed simultaneously.

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Structural behaviour of timber folded surface systems greatly depends on the connections ability to transfer the occurring forces between the adjacent elements and finally to the supports. This paper focuses on multiple tab-and-slot joints (MTSJ), where digital prefabrication is used to integrate connectors through plate geometry. Multiple plates assembled within a large scale folded surface structure were tested to examine the influence of connection detail type on its global structural behaviour. For this purpose an innovative test setup was devised that approximates uniformly distributed surface load. The connection details used were chosen with respect to preliminary small scale bending tests. Three groups of distinct large scale structures were tested: 1) structures with miter joint detail and adhesive applied along the edges; 2) structures with open slot MTSJ; and 3) structures with closed slot MTSJ. Extensive investigation into the load bearing behaviour and failure propagation for each of the three different types of structures has been conducted.For analysing their feasibility, the tested structures were also reviewed in terms of fabrication time, assembly and on-site construction. The obtained results show that even though adhesively joined structures provide highest structural stiffness, they exhibit multiple disadvantages when considering building scale applications. Open slot MTSJ structures results indicate that these joints cannot provide sufficiently reliable structural behaviour. Structures with MTSJ closed slots show that their joint geometry greatly improves both the ultimate load-bearing capacity as well as stiffness. Furthermore, by transferring the edge occurring forces mainly in compression, they provide additional ductility to the global system. Within the scope of this paper, closed slot MTSJ proved to be a very efficient connection type which can constitute a robust folded structural system made as a multiple assembly of thin timber plates.

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