SHAPE AND COST OPTIMIZATION OF POST-TENSIONED I-GIRDER

Abstract

Nowadays in India most of the bridge girders are designed as prestressed concrete (PSC) girders. The reason behind wide use of PSC girders is its facileness of fabrication, modest self-weight, structural proficiency and reasonable maintenance etc. Now in order to use PSC girders over reinforced concrete girders or steel girders, it is mandatory to use the materials more economically as compared to RCC or steel girders. This paper presents an optimization of PSC I-girder with respect to economical use of materials. The intent of the present study is to lessen the total cost of girder with respect to materials in the design process of PSC I-girder. In order to optimize the cost, the c/s parameters of girder namely width of web, width of top flange, width of bottom flange, girder depth, thickness of top and bottom flange are considered as variables in the optimization program. The whole design of the optimized girder is done using Matlab function with nested for loops and the designed section is checked against certain constraints as per IS:1383-1980 and American association of State Highway and Transportation Officials (AASHTO) specifications. Optimum design of Igirder is done by the Matlab program which leads to give the optimum cost of the girder.