A building is designed for seismic so that it remains standing after the earthquake so that people can safely leave the building. On inspection of the building, damage may be found which renders the building unsafe to occupy and therefore useless. The building will therefore need to be demolished and rebuilt.
The purpose of Earthquake design is to protect people, not buildings (or equipment). Although there will be regulations requiring that specific very important buildings and equipment continue to safely operate after an earthquake. (Clean water infrustructure, electricity, hydro dams, etc.).
I 'guess' the ASME code follows the same philosophy. If an earthquake occurs while secondary thermal displacement stresses are at the limit then the earthquake will push the stresses beyond the limit further into the plastic region potentially rendering the equipment too damaged to continue to safely operate (and therefore will need to be repaired or replaced), however rupture and therefore danger to people will not occur.
You can voluntarily opt to include T into your design if you wish. However, it will potentially cost you financially.
