Coordinated actions for stretched structure
The Structures Fire Safety Department then assessed the safety, feasibility and risks of tearing. It worked in cooperation with the SOCOTEC inspection office and CSTB roof specialists, with the objective of validating a non-traditional technique based on experiments and expertise. What is the real mechanical strength of the fabric after allowing for aging and installation conditions? What is the creep? Do tests carried out on models confirm values of the fabric strength calculated by the design office?
Evaluation by expertise and experiments
The favourable ATEx issued by CSTB then allowed the contractor to manufacture and install the Montrouge outer roof in accordance with a quality plan that it wrote internally. A particular comment was made for the transport, handling and placement of the fabric: "The shape of the fabric is determined using patterns, and then by cutting and welding strips, just like a boat sail, says Patrick Delmotte, CSTB engineer. This large and fairly heavy fabric is entirely manufactured in the workshop, and then delivered to site in a single piece. It is also coated with PTFE, in other words polytetrafluoroethylene. All the transport and handling problems that might be expected then follow…” PTFE is better known under some of its trademarks like Teflon, and has a very low coefficient of friction and excellent anti-adhesive properties. In everyday life, it is applied as a coating on some cooking utensils and in the form of plumbing tape to make threaded assemblies leaktight. In Montrouge, it will prevent rain, dust or other residue from sticking to the fabric. But this coating is fragile. Therefore, it was essential to take great care in folding, storing and placing the fabric, obliging the contractor to scrupulously respect the phasing of installation operations.
Location: 50 avenue Jean Jaurès, Montrouge (92)
Client: CEREP Montrouge SARL
Assistant client: Artequation
Project Manager: Wilmotte & Associés
Engineering design office: RFR
Construction design office: IF Ingenieurmeinschaft
Fabric supplier: Verseidag
Membrane production: Graboplan
Membrane placement: Pfeifer
Inspection office: SOCOTEC