On June 26, 2005, about 1050 eastern daylight time, a Cessna 172M, N80802, was substantially damaged during an aborted landing at Union County Airport (MRT), Marysville, Ohio. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight, which originated at Bluffton Airport (5G7), Bluffton, Ohio and was conducted under 14 CFR part 91. According to written and verbal statements provided by the pilot, after arriving in the vicinity of Marysville, he entered a right traffic pattern for runway 27, in order to avoid an aerobatic competition that was being held on the opposite side of the runway. While on the final leg of the traffic pattern, he extended the flaps to 20 degrees and reduced engine power. As he crossed the runway threshold, he leveled the airplane, and held that attitude for about 1,500 feet. He then flared for landing. As the airplane touched down, it "veered" to the right, and he attempted to compensate. The airplane then crossed over grass next to the runway, towards a crowd that was observing the aerobatic competition. The pilot then decided to abort the landing. After adding full power, disengaging the carburetor heat, and increasing the airplane's pitch attitude, the right horizontal stabilizer came into contact with a taxiway sign. The sign was located approximately half way down the side of a taxiway that paralleled runway 27. Assuming that the landing gear had made contact with the sign, the pilot continued his climb, which became uncontrollable, and the stall warning began to sound. While attempting to level the airplane about 1,200 feet above mean sea level, the pilot realized that the stabilizer had contacted the sign, and not the landing gear. After gaining control of the airplane, he declared an emergency, and transmitted on the common traffic advisory frequency that he was going to make a left crosswind turn for runway 27. As he made his left turn, he requested that the "aerobatics box" be cleared, and he continued his approach for the runway. As the pilot assessed the situation, he determined that elevator was jammed; however, he was able to control the altitude of the airplane by adding power to climb or by reducing power to descend. He then added power to climb to 2,000 feet msl, turned a left downwind for runway 27, and began his preparation for an emergency landing. At a point abeam the "numbers" for runway 27, he reduced power, and started his descent. He made normal radio position calls making note of his emergency. The final approach, flare, and landing were uneventful. The Union County Airport Authority conducted an inspection of the area around the parallel taxiway for runway 27, and found that the airplane had struck and destroyed a runway edge light, a direction sign for the runway exit, and a taxiway location sign. No tire marks or ground scarring were noted on the asphalt for runway 27, the parallel taxiway, or the surrounding turf covered areas. A postaccident inspection by an airframe and powerplant mechanic revealed wrinkling of the skin on the right horizontal stabilizer along with impact damage to the tip and leading edge. Compression buckling was evident on the left side and lower skin of the aft fuselage, and the bulkhead just forward of the tailcone was damaged. The pilot held a private pilot certificate with airplane single-engine-land and instrument ratings. His most recent Federal Aviation Administration first-class medical certificate was issued on June 16, 2005. He reported 92.3 total hours of flight experience. A weather observation taken at Ohio State University Airport (OSU), located about 15 nautical miles south east, at 1053, reported calm winds, visibility 5 statute miles in haze, sky conditions clear below 12,000 feet, temperature 81 degrees Fahrenheit, dew point 69 degrees Fahrenheit and an altimeter setting of 30.15 inches of mercury.