Reliable experimental testing methodology for reciprocal structures

Steinmetz, Martin [UCL] Sgambi, Luca [UCL] Latteur, Pierre [UCL]

Reciprocal structures are known to resemble "pick-up sticks" due to their architectural appearance devoid of apparent hierarchy. They consist of elements that are both supporting and supported, thereby complicating both their design and construction, as well as their structural analysis. Paradoxically, they are infrequently constructed despite the abundant scientific literature. This imbalance is partly explained by the fact that this literature mainly addresses geometric aspects without delving into the stability rules and modelling of connections and supports. Only a few researchers have undertaken experimental tests to validate their numerical models, yielding inconclusive results. They have notably highlighted the difficulty of measuring and modelling the behaviour of connections between beams. This article is part of a comprehensive effort to define and experimentally validate complex reciprocal structure stability, design, and calculation rules. Specifically, it outlines a reliable experimental methodology, including the testing protocol and setup, as well as data collection and post-processing. It is applied to an elementary planar reciprocal structure composed of three circular steel tubes, whose simplicity facilitates modelling, measurement and conclusions. The objective is to validate this methodology before applying it to more complex reciprocal structures.