Inspired by Antonio Jiménez Torrecillas’ intervention with wood in the Torre del Homenaje de Huéscar, the Baena’s Castle rehabilitation incorporates structural wooden walkways of iroko wood with a singular design as a connection between its towers.
Structurally, they constitute an innovative system in which wood collaborates with linear stainless steel elements, functioning in a similar way to a flat grating.
The walkways are formed by 80x45mm and 30x45mm wood squares that are linked by means of glued wood-wood joints, forming “U” and “L” pieces. For this purpose, we design two types of ties, single tenon and double tenon, both with a blind mortise and mortise and tenon. The glued joint is tested, in an independent laboratory, for shear and delamination to determine the best performance.
The wooden “U” and “L” are joined to form modules by means of a system of AISI 316 stainless steel rods and nuts. Polyethylene spacers are provided to ensure a constant 12mm separation between pieces. Once the type of joint and the construction system are determined, we fabricate a full-scale module and simulate the most unfavorable walkway situation. It is subjected to load tests to determine the real stresses and deformations to which it could be subjected. This is when the importance of the tensile stress in the plane of the module that is anchored to the walls of the castle is detected.
Fabrication of structural walkways
Then for its manufacture we start from the choice of a durable wood species for the use class 3-4 to which the walkways are exposed, the iroko _milicia spp. It is made by making an exhaustive selection: wood from heartwood only. Radial and straight-grained cuts and a moisture content between 14-18% are sought. In the final woodworking, a second selection is made, using the pieces with the straightest direction for the most exposed walkways.
Each walkway requires a previous study. They are made up of independent modules that are delivered to the site completely finished. This makes it possible to replace any part that may deteriorate over time. For its installation, it is only necessary the previous leveling of the battens that are anchored to the canvases of the castle. The battens are fastened with chemical anchors to withstand the lateral thrust stresses transmitted by the footbridge railings themselves.
Undoubtedly, this research to design and develop structural wooden walkways in this species, presents the possibility of covering larger areas. This will allow us to solve different types of spatial and functional requirements. We are pleased to be able to study the problems of each project to achieve appropriate and potential solutions for immediate and future cases.