Complex sentence: To protect from a possible explosion, the launch pads at LC-39 were located more than three miles from the Vehicle Assembly Building; still, the sound pressure was much stronger than expected and buffeted the VAB, Launch Control Center and press buildings.
Split into simpler sentences: To protect from a possible explosion, the launch pads at LC-39 were at least three miles from the Vehicle Assembly Building. However, the noise was much stronger than expected and buffeted the VAB, Launch Control Center and press buildings.