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.
