The pilot landing the tailwheel-equipped biplane reported he was unable to correct for winds after touchdown and decided to abort the landing. During takeoff the biplane's left lower wing struck a taxiway sign. A Federal Aviation Administration (FAA) Air Safety Inspector performed a subsequent examination of the biplane, and documented and photographed substantial damage to the bottom left wing spar. The pilot reported no pre-impact mechanical malfunctions or failures with the airplane that would have precluded normal operation.