DefinePK

Abstract

Experimental programmed was carried out to investigate the influence of external prestress on composite steel I-girder decks. This program included fabricating and testing twelvescalesdown 1/4, were designed according to AASHTO LRFD 2012 standard specification. Each girder was test as simply supported with span of 3.90m and classified in six groups. The first and second groups consist of two girders have a concrete compressive strength of 50 MPa. The third and fourth groups consist of two girders of concrete compressive strength of 70MPa. The fifth and sixth groups consist of two girders of concrete compressive strength of 90MPa.In all groups; the girder has straight eccentricity and deviator at the mid span. The applied loaded incrementally up to failure under the action of two point loads for each increment of load. The prestressing force in strand of diameter (12.7 mm) in the girders of group (1, 3and 5) was (9) Ton (stress equal to 918 MPa = 0.493 fpu) applied after setting the superimposed dead load on RC deck slab, while in group (2,4and 6) was (7) Ton (stress equal to 714 MPa = 0.384 fpu). The variables in the experimental investigation were the compressive strength of the concrete (50, 70, and 90 MPa), level and path of the prestressing force and their paths straight or deviator (80, 120, 160 and 200 mm), with or without deviator and the magnitude of the applied prestressing force (7 Ton and 9Ton). The percentage increase in stress in external prestress strand from ultimate stress in strand (fpu=1860 MPa) after applying two point loading were rang from (0.16 to 0.39 fpu of strand).