Date

1-1-2020

Document Type

Thesis

Degree

Master of Science

Department

Civil Engineering

First Adviser

Dan M. Frangopol

Abstract

This thesis presents life-cycle environmental assessment (LCEA) for carbon and A1010 steel girder bridges. This thesis setup a quantitative life-cycle environmental impacts model to help decision makers to choose the appropriate material for steel girder bridges under different environmental conditions. The overall LCEA process is structured according to ISO 14040 and ISO 14042 which are talking about the life-cycle impact assessment of structures. The LCEA process includes the product category rules development, life-cycle inventory analysis and life-cycle impact analysis. Mote-Carlo simulation is used for inventory and impact analysis and Multi Criteria Decision Aid (MCDA) method is used to determine the weighting factors for each impact category. Three inventory categories are analyzed for inventory analysis: (1) carbon dioxide, (2) sulfur dioxide, (3) nitrogen oxides. Three environmental impact categories are analyzed for life-cycle impact analysis: (1) global warming potential (GWP), (2) acidification potential (AP), and (3) Eutrophication potential (EP). The weighting factors of three impact categories are determined according to three environmental criterions: scale, duration and reversibility. By integrating the weighting factors and life-cycle impact values a weighted life-cycle environmental impact value is obtained. This weighted life-cycle environmental impact can be used to compare the environmental impacts of these two different types of steel girder bridges.

A study case of bridge E-17-AH in Colorado is also included in this thesis which is an example of application.

The results of the LCEA showed that the carbon steel girder bridges have lower initial environmental impacts than A1010 steel girder bridges. However, the total life-cycle environmental impacts for A1010 steel girder bridges are lower than carbon steel girder bridges. The results indicates that A1010 steel is a cleaner alternative to carbon steel for bridge construction.

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