Seismic risk analysis
The procedure on which all seismic work is based: the seismic risk analysis.
The seismic vulnerability of a structure is a rating of the structure’s resilience in relation to the seismic area it is in and/or ground acceleration.
Different investigations can be carried out to determine buildings’ seismic vulnerability, going into different levels of detail: for example, there are more quality-based estimates, based on information gleaned from the specification sheets of the main features of the building’s component elements; and complex numerical analyses using linear and non-linear calculation methods.
Estimating vulnerability based on specification sheets is done as part of a site inspection, associating a certain class with a set of parameters that are representative of the type of structure and the state of repair of the main load-bearing elements. A rating scale is associated with each parameter that varies based on the class that can be associated.
In Italy, the process of estimating a building’s seismic vulnerability rating is dictated by the “Safety assessment” design procedure laid out in section 8.5 of Italy’s building code (NTC), and can be narrowed down into the following steps.
- Fact-finding investigation: the current state of the construction is determined by means of floor plan, elevation and structural surveys, and surveys to determine the structure’s state of repair and level of deformation;
- Historical/critical analysis: this is the tool that informs the designer’s reconstruction of the current strain in light of changes and events that have affected the building over time;
- Determination of mechanical properties of materials: assessment of the materials’ strength by means of investigations on site or laboratory testing;
- Determining levels of knowledge and resulting levels of confidence: reduction factors for the mechanical properties of materials are determined that decrease as the level of detail of the investigations increases;
- Structural analysis and determination of the vulnerability of the existing structural system;
- Proposal of any local strengthening/improvement/retrofit work and assessment of the optimal cost-benefit ratio
Seismic risk assessment is a subject of paramount importance when dealing with issues such as seismic retrofitting and improvements. Find out everything there is to know about seismic risk analysis.Read more detailed informations on seismic risk analysis
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