Seismic Engineering is not often thought of as immediately relevant within the UK construction industry. However, Britain typically sees an earthquake of magnitude 4 or above which is considered significant on the Richter Scale approximately once every four years or less. As such, structures of high importance and sensitivity may be required to meet the design requirements of Eurocode 8 “Design of Structures for Earthquake Resistance. General Rules, Seismic Actions and Rules for Buildings”. Such structures may include nuclear facilities, tunnels, bridges and sky scrapers to name a few.
Seismic acceleration may be defined as the acceleration of the ground due to seismic activity, whereby the ground its self moves and accelerates. This movement can occur both laterally and vertically. The effects of bidirectional acceleration may also be additive as well as destructive.
The effects of seismic acceleration can have devastating consequences to a structure which is not adequately designed to mitigate this. It can ultimately lead to complete collapse as was seen during the catastrophic events of the Christchurch Earthquake in 2011.
Various methods exist to mitigate the risk of damage from a seismic event and it is the engineers responsibility to determine the most suitable system in combination with the clients requirements. Some examples are: Tuned Mass Dampers, Foundation Isolators, Plastic Hinges and Chevron Bracing as well as Hydraulic Dampers. Each one of these methods aims to mitigate the effects of seismic movement by nullifying the response of the structure, either via energy absorption through damping or altering the frequency response of the structure although these two methods are not mutually exclusive and are often used in combination to provide the most effective cost efficient solution.
At SGL we are experienced in seismic design of structures both within and outside the UK. Our team are experienced designing on and offshore structures subject to seismic design loads. In addition to structures, SGL are also experienced in the seismic design of none structural items such as ME&P service support systems to ensure their safe and consistent operation during and following a seismic event in accordance with Section 4.3.5 of BS EN 1998-1:2004 +A1:2013.