Be careful with this one. A category IV building needs special consideration for what "service level" winds will be. What is the building? Is it a level one trauma center? The emergency response coordination headquarters for the region? If so, "service level" may need to be strength level to ensure that it will be fully functional during a design event.
We allow things like houses and shopping centers to have much lower service level wind loads because, in the event of the "big one" the only concern is that the building not collapse on anyone inside. There is an inherent expectation that the building doesn't need to be usable after the event, so long as it doesn't fall and hurt or kill anyone. Significant repairs and/or demolition and rebuilding will be necessary. For critical infrastructure and facilities, the standard may be different. It may be that it just needs to survive but can be repaired - in which case lowering the wind load for service checks may be appropriate. But if it's a critical facility that needs to remain operational during and after the event with little to no interruption, you need to assign a higher "service" level.
