Rapid assessment of structures in low to moderate seismicity regions

Current seismic assessment procedures have traditionally been based on the concept of trading off strength with ductility (displacement) to provide sufficient capability for the structure to absorb and dissipate the energy demand from an earthquake. As a result, structures in high seismicity regions are designed to undergo large displacements whilst maintaining their lateral strengths in an earthquake. However, the energy demand of a small to medium magnitude earthquake could subside as the strength and stiffness has deteriorated. Consequently, a structure which is deemed unsafe by conventional assessment criterion could actually survive the ground shaking. This paper proposes a simple method for the rapid assessment of structures in regions of low to moderate seismicity. Structures built in these regions have traditionally been considered to possess very limited ductility and deemed not to comply with current code provisions. Conventional force-based computations can be very costly particularly for asymmetric structures where dynamic torsion is involved. The proposed procedure will result in significant savings in time and costs with the assessment process when a large number of structures are to be assessed.