Effect of cost on span length of simply supported prestressed concrete I-section girder bridge

Abstract

In recent times large numbers of pre-stressed concrete girder bridges have been constructed under Roads and Highways Department and Local Government Engineering Department in Bangladesh. Prestressed concrete Fly Over construction has also been started in Dhaka city corporation area and it will be largely used in future. Cost variations with respect to the span length are not readily available to the engineers on the basis of the present market prices. So cost information is very essential for prestressed concrete girder bridge construction. Effect of cost on span length of simply supported prestressed concrete 1- section girder bridges system has been presented in this project work. A computer spreadsheet program has been developed for the analysis and design of the bridges according to the bridge design specifications of AASHTO (2002). For calculation of quantities a spreadsheet program has also been used. RHD rates of schedule (2008) have been used for calculation of cost. In this study the width of the bridge has been considered as per requirement of RHD regional roads. Five sample span length (15m, 20m, 25m, 30m, 35 and 40m) and five number of girder (AASHTO PCI I girder) have been used for the idealization and the requirements of this project works. Total cost and per unit length cost for each bridge has been calculated separately and then presented graphically with respect to span length. Costs of 02 real life projects ofJOm span and 35m span prestressed concrete 1- section girder bridges have been compared. It has been seen that total cost of superstructure of prstressed concrete I-section girder bridges for the span length 30m and 35m for real life project and that of the study works are nearly same. Based on some assumptions, this project work has been studied and it has been found that the variation of total cost of superstructure of simply supported prestrssed concrete I-section girder bridges from span length 15m to 40m is almost linear. Cost has been increased with increasing span length. Total cost of superstructure has been presented graphically from span length 15m to 40m. Unit length cost of superstructure from span length 15m to 40 has been found constant, 326.00 thousand Taka per meter.