Cap decks used in slim floor system for reducing floor height act as molds for forming floor slabs in structures with a span of up to 6m without temporary supports. When deep decks are employed in a structure with a span of more than 6m, the problem of defection occurs. This study suggests placing tendons at the ends of cap decks in order to create cambers and control defection when preload is applied. Uniformly distributed load was applied by an UTM to the two L/4 points of specimens to observe the deflection of preloaded cap decks. For the test, three 7.5m specimens were fabricated. One of them was a plain cap deck specimen and the others were those with tendons (PC strands or steel bars.

Deep Deck plate is suitable to long span structures because it has larger flexural rigidity than other shape deck plate. but Deflection is critically proportional to span length than other factors. and large deflection makes works anxiety and possibility of structural problems high after casting concrete. to overcome these problems, Preload is introduced to control the deflection of deep deck plate that ha s long span. So in this study, residual strength of preloaded deep deck plate is evaluated by FEM analysis method. for this study 4 analysis models is used and have each preload. Target preload for analysis models is when deck plate cambered to 30mm. 0.0, 0.8, 1.0, 1.2, times of target preload are applied to each analysis models. In result of analysis, Preload influence residual strength of deck plate. And much preload degrade strength of deck plate.

These days, the Composite Slabs with Deep deck plate was commonly used in domestic construction site, and, the application of the Slim Floor system was increased from the Enlargement and High-rise Building. But, Slim Floor system using the deep deck was shown safety problem caused by the deflection and local buckling in construction phase when used to more than 6m. Therefore, for solving the problem, the installation of the shores is essential. This study is realize the long span slab without shores from control the deflection through applied the pre-tensioning elements in cap deck. In addition, by applying the pre-tensioning member as the tensile member of the Cap Deck composite slab, the pre-tensioning member for the shores tries to be used as the structural member. Accordingly, to determine the flexural performance of the Cap deck composite slab through the pre-tensioning force in tensile member, and, the composite effect of the cap deck composite slab by the experiments.