If you are the one charged with the shoring operation yes, I think. I am not familiar with the US codes, just read some of them 3 or 4 years ago.
But if you have one important work, say a bridge, on shoring, it would be only rational to try to ensure the survival of the investment.
One thing to consider is that the likelihood of have one strong EQ of any assumed intensity is far less for the 2 years period of construction and far less for one always ongoing 21 days shoring or so. This could be accounted from first science of construction principles, and surely would be very deffendable in Spain from codes even. It is also customary to reduce safety factors for on construction loads.
Furthermore is worth of consideration the study of alternative ways of construction that nullify the need of proceeding with much difficulty on this regard. For example for completely shored decks the piles would be standing and if the formwork was stiff enough in the "plane", shoring itself would be leaning columns on piles and abutments...but the problem in the deck would stand. Even for 6 hours some minimum cut off to the reduction in the intensity of the EQ would mean necessary changes for the horizontal formwork, since a deck is quite massive.
That this is the case with important structures is quite clear; no authority nor the ppl would approve negligence causing, say, a climbing crane falling on a seismic event while in construction, if the in construction building has not tumbled. Yet in any case we still see failures on shoring itself (I think there has been a important one -bridge- this year) without EQ. That a 15 m segment is ruined makes the local news but if a 100 m span rounds the world.
And the thing is simply, if it is additional work, it must be paid. Just in case someone thinks one must overextend to infinity in exhaustion. Something it seems happen with legislative profligacy on everything and as well on technical warrants and checklists. You want something as good and safe and warranted as, you pay it.
It's certainly unlikely that you will have to design temporary works like shoring/scaffolding for EQ. In fact,even for wind/flood loads,we only take about a 5 year return period for design. So unless you are in Japan or on a volcanic island,your EQ magnitude for such a return period will be negligible
abhio, technically what you say is true, the thing that it is usual to establish a inferior limit to the intensity of EQ yo must use for analysis...so all is a matter of carefully reading the relevant code.
