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The Engineering Use of the 2020 National Seismic Hazard Model for the UK

Session: Recent Engineering Uses of National Seismic Hazard Models I

Type: Oral

Date: 4/22/2021

Presentation Time: 03:00 PM Pacific

Description: 

The Eurocode 8 (EC8) is the European Standard for the design of civil engineering projects in seismic regions. It was published in 2004 and a revision is expected in 2025. The design seismic action of a structure depends on a building classification that consists of four classes depending on the consequence of failure: CC2 for standard commercial and residential buildings; CC3 for structures whose seismic resistance has important social consequences; and CC4 for structures with the large consequence of failure. The National Annexes to the EC8 set out Nationally Determined Parameters (NPDs) that are used to estimate the elastic response spectrum, such as the maximum response acceleration at 5% damping and the acceleration thresholds for different seismicity areas. The NDPs are derived from the national seismic hazard model (NHSM).

In the United Kingdom (UK), an intraplate region with low levels of seismicity, we have recently updated the NSHM. Since the 2007 NSHM, there have been significant advances in the seismic hazard methodology, particularly with respect to how ground motion and its uncertainties are modelled. The 2020 NSHM for the UK accounts for an updated earthquake catalogue, reassessment of the catalogue analysis and the seismic source model, and advances in the ground motion modelling. The national seismic hazard maps derived from the NSHM are expressed in terms of peak ground acceleration and response acceleration at 0.2 s and 1.0 s for 5% damping on rock and various return periods. The maps confirm that seismic hazard is generally low in the UK and slightly increases in Wales and north-central England.

The 2020 NSHM and the new seismic hazard maps for the UK are used to provide the NPDs in the National Annex for the revised EC8. For most CC2 structures, the 2020 seismic hazard maps suggest that the acceleration threshold is unlikely to be crossed for a given return period. The British Standard Institution sub-committee for EC8 is evaluating whether to recommend a seismic design for CC3 and CC4 structures to the entire UK as whole or on regional basis.

Presenting Author: Ilaria Mosca

Student Presenter: No

Authors