Building seismic repairs

This article is dedicated to the consolidation of buildings in the face of seismic risk, as well as to the repair of structures shaken during an earthquake. It reviews the state of the art in seismic rehabilitation of structures using steel solutions, while presenting recent technologies such as the use of metal diaphragms and shock absorbers based on shape memory alloys.

All these techniques were developed in Japan, the United States or Europe, i.e. in countries with severe seismic risk zones (Italy, for example, in Europe). France is very concerned by earthquakes, and this threat applies not only to mainland France, but also to territories such as the French West Indies, which are highly vulnerable to seismic hazards. The Plan Séisme (see link in the Pour en savoir plus section) and the new zoning for overseas departments call for the seismic resistance of public buildings to be upgraded. As a result, major reinforcement work is required, for which steel is likely to provide a quality response, as we shall see below.

Regulatory approaches are now governed by Eurocode 8, Part 1-4 of which deals with the reinforcement and repair of buildings. Details of anti-seismic devices are given in standard EN 15129.

Seismic retrofitting is a subject in its own right, with a multitude of cases that are difficult to grasp from a regulatory point of view. In fact, this exercise calls on the state of the art and the engineer's good critical sense to interpret and adapt regulatory texts. Above a magnitude of 6.0 on the Richter scale, the desolation that follows an earthquake is impressive. Once the aftershocks have been purged, and there is no longer any hope of finding survivors, it's time to secure the shaken buildings and quickly decide which are viable and which are definitively out of order for demolition.

The impact of an earthquake is not necessarily the same in all parts of the same city, where different types of construction can be influenced by topography. The nature of the subsoil and the specific constitution of the structure (construction techniques and materials). Obviously, the means of repair employed must take these latter parameters into account. Each structure is assessed on a case-by-case basis, following a detailed inspection of the damage. The post-earthquake period is also a good opportunity to review the seismic approach.

Successive earthquakes in a region such as San Francisco have led to the need to repair or reinforce buildings that have survived the various quakes. Steel can play a decisive role in such reinforcement work, regardless of the material used in the construction, thanks to its flexibility in use and the large number of anti-seismic solutions it can develop....