ARGH Blast Door

Two armoured panels drive apart on eight telescoping hydraulic rams while powered lock dogs withdraw from the frame. Every moving section carries its own collision and armour, so the doorway is genuinely solid when shut and genuinely open when not — you can shoot the panels, and hits land where the panels actually are.
Comes in two versions. The automatic door opens as you approach and closes behind you. The manual door waits for you to open it. Both can be locked to a faction, or left open to everyone.
Place from the Game Master entity browser under Objects.