Comparison Between Europe And U.S.A Guidelines On Design And Detailing Of Weathering Steel Composite Bridge For Enhanced Corrosion Performance

Weathering steel has been in use for bridge construction for a number of decades.Successful application of weather resistant steel for highway bridges requires a better understanding by the engineers on the structural details,the macro and microenvironment that initiating and supporting corrosion process at a particular bridge site to be able to design and detail a bridge structure that considers all major factors affecting its performance.Failure to perform due to unsatisfactory corrosion of a number of weathering steel composite bridges constructed in earlier ages particularly in the Europe/UK,Japan and United States of America(U.S.A)has become a subject of interest to researchers.Studies by researchers are ongoing particularly on subjects related to effects of different environment on performance of weathering steel and design details for enhancing corrosion performance of weathering steel used in composite bridge construction.This thesis considered a case study for application of weathering steel(WS)for highway bridge construction in Dar es salaam,Tanzania.This study aims to provide useful information on use of weathering steel to the selected bridge environment by evaluating the suitability of Dar es salaam environment on use of the material.Environmental corrosivity of the site was classified based on international standard ISO9223 similar to the standard guidelines applicable in the United States of America and Europe particularly the United Kingdom.Predetermined information for environmental corrosivity was utilized in this thesis to establish values for sacrificial thickness deducted to the steel I-girder section dimensions considered in structural analysis.Comparison of structural analysis and design verification results of a sample simply supported composite weathering steel I-Girder superstructure at strength limit state shows that weathering steel section capacity for flexure moment resistance computed according to Eurocodes has a reduced value to 30% of a weathering steel section capacity for flexure moment computed using AASHTO LRFD specifications.Lastly,the thesis provides a detailed description on different design details alternatives for enhancing the corrosion performance and long term durability of a sample weathering steel composite bridge superstructure as recommended in different standard specifications and guidelines applicable in the referred regions.