WP6. Seismic risk assessment of industrial structures

Tools and methods for the seismic risk assessment of industrial equipment structures will be developed in this WP using the three alternative procedures.

The first procedure is based on convolving the vulnerability curves, obtained from WP5, with the hazard curve of the site that the structure is built. This approach is described by Eq. (1) and is the most common way to calculate the mean annual frequency (MAF). The MAF calculation will be based on hazard curves that have been developed using Greek seismic data. As intensity measure (IM) we will use the peak ground acceleration versus one or more spectral values at characteristic periods to better capture the important effect of spectral shape (Baker & Cornell 2005, Vamvatsikos & Cornell 2005). In all cases we will study the sensitivity of our MAF estimates on the IM chosen and we will propose a viable alternative that combines efficiency and sufficiency with low-cost hazard estimation.

The second procedure is based on closed-form relationships that will serve as a practical approach for assessing the seismic risk. This approach is based on the work of Cornell and his co-workers (Cornell et al. 2002, Jalayer & Cornell 2002) and requires locally approximating the vulnerability and hazard curves as power functions of the intensity measure. This idea was initially proposed for steel buildings in the FEMA-350 (2000) guidelines and it allows for a simple, practice oriented format using load and resistance factored design (LRFD) concepts similar to current design codes.

Finally, the seismic risk will be directly estimated from the ground motions of WP2. Generating ground motions that correspond to a given magnitude and distance scenario, we can directly calculate the MAFs within a Monte Carlo Simulation framework, without splitting it to a vulnerability and hazard analysis problem. This approach will serve as benchmark solution in order to validate the previous two simpler methodologies.

The research teams of NTUA, UPa and ITSAK will contribute to this WP, while their efforts will be coordinated by the NTUA team. The NTUA and the ITSAK team will contribute to the risk assessment methodologies and the UPa group will work on the generation and the selection of ground motions, where required. As discussed previously, all teams have extensive research experience in their respective fields that will prove instrumental for the successful completion of the work package.

Key intermediate goals: Perform risk assessment using alternative methods, assess the efficiency (accuracy and computing cost) of the proposed methods when applied to industrial equipment structures.