At about 1430 local time, the Piper Arrow hit a runway construction barricade during a simulated forced landing at the DeKalb Taylor Municipal Airport (DKB)and was substantially damaged. The pilot and flight instructor were practicing a simulated forced landing to a runway with its threshold displaced 600 feet for construction. Both the first 600 feet of the existing runway surface and the new pavement were marked with yellow painted chevrons, indicating those portions of pavement were closed for landing, takeoff and taxiing. There were four construction barricades positioned at the intersection of the existing and new pavement sections. During the simulated forced landing, the pilot felt the airplane was not going to make a landing on the existing runway and would probably touch down on a section of the new part of the runway. He increased engine power to arrest the descent, but the airplane touched down on the new pavement, bounced and landed a second time on the existing pavement. The pilot noticed the airplane was damaged during a post-flight inspection. The CFI later stated he had not noticed any construction barricades at the end of the runway.