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COMPARATIVE STUDY OF STEEL I - GIRDER AND PRESTRESSED STEEL I – GIRDER AS PER IRC24:2010
Authors: DHARA SHAH, DEVANG PATEL & HETAL JANI
Number of views: 567
Prestressing of structural elements especially steel girders improve their load bearing capacity and rigidity along
with reduction in material consumption and overall cost for the same loading. The present study aims at preparing
expedient interface for design of Steel I-Girder and Prestressed Steel I-Girder as per IRC24: 2010, encompassed through
parametric study of two lane road bridges for varying span to depth ratios, considering 15m, 20m, 25m and 30m of spans.
The analysis is done considering dead load, superimposed load and moving load as per class A-2 lane / class 70R loading.
Design of prestressed steel I-girder is done by varying the diameter and number of strands. 9.5 mm, 11.1 mm, 12.7 mm and
15.2 mm diameter class B 7-ply strands are considered in 4, 8, 12, 16 and 20 numbers of groups. The cost comparison is
done as per prevailing market rates. A definite increase in the bending capacity of steel I-girder is found when prestressed
with strands, without any enhancement in shear capacity. Prestressed steel I-girder provides shallower depth of the girder
for same L/D ratio. With increase in the strand area and number of strands, bending capacity increases for same L/D ratio.
Prestressed steel I- girder shows cost saving up to 50% for 15m span, 37% for 20m span, 28% for 25m span and 20% for
30m span. Cost of girder per meter length decreases when applying the prestressing force with increase in L/D ratio.