PSC I-TYPE GIRDER WITH OPTIMIZED CROSS-SECTION AND METHOD FOR DESIGNING SAME

摘要

The present invention is directed to a PSC I-type girder with a cross-section optimized which reduces the number of PSC I-type girders arranged between supports by 20-30 pcnt by economically determining the cross-section of the PSC I-type girder, and to a method for designing the same. To this end, a PSC I-type girder with an optimized cross-section according to the present invention includes a lower flange having a width of 0.8-1.2 m, a thickness of 0.18-0.20 m and a hunch thickness of 0.22-0.25 m, and an upper flange having a thickness of two 1/4L spans of the girder measured from the center of the girder in both directions greater than two 1/4L spans of the girder measured from both ends of the girder. The geometrical shape specific parameter of the girder cross-section that is a rotational radius (r) is determined with variations of the width, thickness and height of the upper flange, and r=v(I/A), and the squared value r2=I/A is named a secondary moment of the cross-section per unit area, which is also called rigidity per unit area, and if the rigidity value per unit area is at least 95 pcnt in the span of 27-60 m between supports compared to the maximum value determined with variations of the upper flange, then such cross-section is the optimum cross-section.