A bolt-fastening method was invented for connecting prefabricated modular structures with a purpose of reducing production cost and enhancing delivery efficiency of precast structures by eliminating welding parts. In order to remove welded connections, a drawing part and a bending part were designed and bolted together to easily generate a long support structure. The bolt-fastened structure had a plate deflection of similar magnitude to that of the welded structure, and weighed about 2.5% less. The heat supplied inside the structure for concrete curing had a negligible effect on the deflection of the structure. Since the unit module is only 640 mm long, and welding is eliminated from production to export local assembly, and the long structure is completed only by fastening, significant reductions in shipping cost and local labor cost are expected.

This study was conducted to investigate the proper design of alpha board used to support concrete blocks under high loads. A board height of 50 mm was appropriate to ensure a deflection of 3 mm or less under a load of 5 tons. The trapezoidal shape of the vibration absorbers in the interior of the board reduced the maximum deflection by evenly distributing the deflection across the board width. The height of the board is the most important variable in preventing deflection, and for the same board height, adjusting the thickness of the top and bottom plates was more effective in reducing the amount of deflection than adjusting the thickness of the stiffener. The theoretical solution is a good tool for easily predicting the deflection of the board, as it shows a difference of 5 to 15% from the simulation results. However, as a 2D prediction model, the theoretical solution cannot represent the distribution of deflection over the entire board area, so the 3D simulations are necessary in predicting the amount of deflection over the entire board.