Experimental Study on Strengthening Effect of Plastic Greenhouse using Tension-tie

摘要

The number of cases of collapsed plastic greenhouses in farmlands has increased due to the heavy local snowfall caused by extraordinary atmospheric phenomena in Korea. Consequently, the economic losses of farmers have also increased. However the government policy in relation to damage pretension is insufficient and collapse case is being repeated every year. The main reason for frame collapse is that the moment capacity of a steel pipe is not sufficient to resist a heavy snow load. In this study, experiments were conducted on the current frame system of a plastic greenhouse with a tension-tie. The frame consisted of two sections (Φ25. 4×1.5, Φ31. 8×1.5), and its span length was 6,5 m. A temporary tension-tie using a steel wire and a fabric rope were connected to the two joints that a curved beam and a straight column were connected. The pretension force was applied at the tension-tie, and a verti cal force simulating snowfall was applied until failure. The fabric rope frame increased the load carrying capacity by 10%～45% compared to the normal frame without a tension-tie, and the steel wire frame increased the load carry ing capacity by 58%～73% compared to the normal frame without a tension-tie. Steel wire was found to be more effective as far as strength is concerned, but its connection details and pretension application are more difficult and complicated than those of the fabric rope. The test results thus show that the tension-ties are very effective to in crease the load carrying capacity of frame.