Frame and Form

If you enjoyed the Pont Trencat article, today we present the interview that the structural designerXavier Font conceded us. Following, we will immerse a little into the rich structural world and we will discover, in Xavier words, the concerns, motivations and objectives behind one of his most celebrated works.

Q: On the web Roman Bridge 2000 it is justified some of the decisions about the restoration design of Pont Trencat. It is a valuable text because it helps us understanding the work. For example, explained the initial lack of information to make a faithful restoration of the bridge before its destruction, and argues that current restoration materials and techniques preserves the old bridge value for future generations. Aparentemente en el proceso de diseño se consideraron a un mismo nivel la alternativa de la reconstrucción y la opción de la restauración hasta que la primera quedó descartada de manera “natural”.  Nos gustaría saber si esta decisión fue fruto de las sucesivas etapas del proyecto o bien si había una predisposición respecto a alguna de las dos opciones. In other words, How much of intuition played a role in the proposed restoration?

A: The choice of restoration was the result of an evolutionary and iterative process, that usually characterizes the development of any project. The closest reference that we had on recoveries of stone bridges were the performances that were made on some bridges destroyed during the Civil War. Was the case Pont del Diable in Martorell, the Pont Vell in Sant Joan de les Abadesses or Pont Vell in Manresa. All of them opted for the functional recovery of the bridge using contemporary structures (in reinforced concrete) stone-coated, with the aim of mimicking the old masonry bridge. This initially led us to propose a reconstruction on the same line. In fact, was hired the first phase of work with a mimetic reconstruction project. However, we gradually become aware that our situation was different from that faced for those responsible for reconstruction, because they have much information about these bridges before destroyed . This was not our case, because we had no reliable information about the bridge before the disappearance of its main arch. The change of mimetic reconstruction to a more daring option, restoring the bridge without trying to recover its original shape, was not before overcoming a heated debate among members of the association Pont Romà 2000 and representatives of the two affected consistories, Sant Celoni and Santa Maria de Palautordera. In response to your question, restoration proposal was the result of a dose of rationality more than intuition, which was gradually taking shape.

ACTUACIÓN Broken Bridge

Q: The design of the restored part evokes the shape of the bridge destroyed. This image was formed from the volumes of the same structure, ie, the board and the bow, and also the empty space between these two pieces. What inspired you to design this formal solution? Any reference work of architecture or sculpture? ( Iask because I wonder if this relationship between volume and emptiness reminds me sculptures from Pablo Gargallo, and I would like to know what reference -in an inspirational level - have been taken in the case of Pont Trencat).

A: It is often difficult to recognize the sources of inspiration from which our ideas born. I know little about the work of Pablo Gargallo, however I've always been a big fan of the works of Eduardo Chillida and Richard Serra; I consider them both masters in managing the formal possibilities of steel. In particular, from Chillida I have always admired the way his work dominates the dialogue between volume and void; and probably, in a non-conscious way, It may have had an influence on the genesis of the shape of the new structure of the Pont Trencat.

wind comb - Chillida

Q: One detail that gives personality to Pont Trencat is the relationship between the arc and the deck. The deck passes through the keystone of the arch. In the Can Gili pedestrian bridge you used the same resource, although in this case the support is not an arc but a tilted pylon. What do you want to transmit with this composition?

A: Although the outcome of these two cases is formally similar, the genesis of each is very different. In the case of Pont Trencat, the point joining the deck with the key of the arch was originally conceived as a rigid interlocking volume of both elements. However, during development of the project were constructive seeing the difficulties of such a solution entailed. This led us to a simplification of this union, subsequently, in my opinion, resulted in a structurally more elegant solution, in which the board rests on the key to a pointed arch, which happens to be a form of state antifunicular generated charges. On the contrary, In the Can Gili pedestrian bridge, and from the beginning was conceived more than dodge the main structure as a support body of the secondary board. In this case it was intended to emphasize the contrast between the massive main structure, actually saves the obstacle from the road, and the slender secondary structure, that complements the way in that part where the users are no longer on the pavement of the road.

Can gateway Gili

Q: Both Can Gili as in Pont Trencat Special care is perceived in the way the bridge into contact with the ground. This aspect is not usually look at the bridges and as a result of this neglect is often perceived a discontinuity, especially at the ends of the bridge with large boards and boards that make a sudden end of the work. How did you approach the design of access routes and bridge supports? Did you consider (so basic) on the preliminary designs, For example, to fit the local topography of each of the possible geometries of the bridge?

A: Since the early stages of the design process, how to spot, and therefore possible access, greatly influence the overall design of my works. Since my first projects, I have always paid special attention to how the bridges come in contact with the ground, so the way it has always largely conditioned the solutions I have proposed. Surely that is why the choice of asymmetric longitudinal typology has been the practice in my work, as is the case of the two bridges above.

Broken Bridge accesses

Q: Also be seen in these transition zones much variety in your designs. Each side, each foundation, has a special and differential treatment. Why? What do you base a different design in each cell or bracket?

A: The dimensions and geometry of the field, the geotechnical characteristics of the subsoil and the limitations on construction process, usually tend to be technical factors that most condition of any bridge design. The proposed overall design arises from the response to these and other more common requirements of each project (Economy, time, availability of technology, Galibi required, …). In this process, land-bridge transitions occur as a result of design decisions taken in developing the overall design and the above requirements. Perhaps that is why my work is unusual in that each point of contact with the ground structure in a form other, because in each case meet their design intent to seek ways in which, in my opinion, the transition is more naturally (while recognizing the subjective nature of this adjective in this context). On the other hand, I find the interface zones are of great interest; in border areas very interesting things always happen. In fact, structure continues to be a conduit for flow of forces, and those points where a change of material or structural element to be analyzed in great detail, but at the same time formal offer great opportunities I have always liked to take. Somehow, I like to draw the viewer's gaze toward them.