Civil Engineering & Steel Structures

Biography

Biography: David Fabie

Abstract

Refurbishment of historical monuments and old buildings highlights the need to increase our understanding of materials and methods to assess the properties of old materials. Increased security factors for safety and possibilities offered in the refurbishment of buildings, generate the need to assess, with efficient and reliable methods, our knowledge of what is by essence unknown : existing buildings. This need is increased since it is usual to find few to none documents from construction, while recent standards require advanced engineering and comprehensive knowledge of materials.

This matter becomes event more relevant when one considers that refurbishment and reconversion of buildings is an essential step to low-carbon strategies in construction. It implies that our understanding of existing structures, materials and details must be assessed with sufficient precision.

In order to develop this strategy we propose to introduce two case studies on which we have been working.

The first case study isthe total revamping of the Eiffel Tower’s north elevator . The Monument was built for the 1889 Universal Exposition and was initially designed to be a temporary structure.The structure used for the support of cranes was later dedicated to the elevators. Made of puddled iron, a low ductility material with anisotropic properties, the structure is now required to fulfill complex verifications according to modern standards (Eurocodes), including fatigue calculations, accidental load cases which lead to high level of stresses. This example shows how our need of security and performance generates an increasing need of knowledge of old materials.

The second case study is the total overhaul of the Montparnasse Tower in Paris. The presence of asbestos in facades compounded with obsolete structure fire protection of the building bring the refurbishment inevitable. Highest high-rise building in Paris after the Eiffel Tower, this tall building is now refurbished with the Client’s wish to increase its height and deliver modern standards to its users. However, the core of the building is located exactly on a metro line, and stands on prestressed concrete beams of great dimensions. The future of this building relies on our capability to mitigate the risks on our knowledge and engineering of its structural stability.

Generally and without consideration of Historical Monuments representing symbols of our past, our real estate heritage must be a support to our future and not some risky heritage, that we had better demolish completely rather than refurbish. When structural elements represent more than 30% of the carbon emissions, this point seems crucial in sustainable development.