Design Solutions for the Royal Alexandra Bridge
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DESIGN SOLUTIONS FOR THE ROYAL ALEXANDRA BRIDGE FOR: PUBLIC SERVICES & PROCUREMENT CANADA EXSPAN STRUCTURAL CONSULTING SERVICES CHRISTOPHE CHAN SING HENNY DUONG KINGTON CHU SOFIA AN JULY 22, 2019 1 Christophe Chan Sing ExSpan Senior Project Manager 200 University Ave West Waterloo, Ontario Canada N2L 3G1 July 22, 2019 Dr. Nadine Ibrahim Senior Project Engineer Public Services and Procurement Canada 140 O'Connor Street Ottawa, Ontario Canada K1A 0S5 Dear Dr. Nadine Ibrahim: The Royal Alexandra Interprovincial Bridge is deteriorating and multiple rehabilitations have taken place over the last decade in an effort to extend the bridge’s service life. These constant rehabilitations have been costly to both the federal government and the local communities of Ottawa and Gatineau in terms of overall construction expense and traffic congestion. Our scope of work for Phase I of this project include an evaluation of possible design options related to either reconstructing the existing bridge or constructing a new complementary bridge. The evaluation was performed by analyzing and comparing in a weighted decision matrix each design option’s life cycle cost, innovativeness, construction impact, traffic flow, excess strength, and ability to preserve the existing bridge’s heritage. It was determined that constructing a box girder bridge to complement the existing bridge is the preferable option over reconstructing or continuing to rehabilitate the current bridge. Therefore, it is recommended that the complementary box girder bridge is chosen for Phase II of the project where it will undergo detailed design, be structurally analyzed, and have construction plans produced for it. Our technical advisor, Dr. Maria Anna Polak, was a great resource in guiding us through the first phase of this project. This technical report was written by our team at ExSpan and has not received academic credit at the University of Waterloo or any other academic institution. Yours sincerely, Christophe Chan Sing Henny Duong Senior Project Manager Technical Analyst Kington Chu An Su Hyun Structural Analyst Structural Designer DESIGN SOLUTIONS FOR THE ROYAL ALEXANDRA BRIDGE EXSPAN STRUCTURAL CONSULTING SERVICES CHRISTOPHE CHAN SING HENNY DUONG KINGTON CHU AN SU HYUN JULY 2019 Summary The Alexandra Bridge is a steel truss cantilever bridge that spans over the Ottawa River between Ottawa and Gatineau. It was originally built in 1900 by the Canadian Pacific Railway. The bridge has been subjected to several rehabilitation programs in the past ten years due to its age. The constant construction work and road closures have had a negative impact on the traffic around the bridge. The main problem is the fact that the traffic on the bridge is continuously increasing while the bridge is deteriorating rapidly and will need more rehabilitations in the future. ExSpan was brought in as a consultant to assess the problem and come up with a solution. Three alternatives were proposed as potential solutions. The first one is to demolish the Alexandra bridge and reconstruct a new bridge in the same location. The new designs that were considered are an extradosed bridge, tied-arch bridge, and cantilever truss bridge. The second solution is to repurpose the existing bridge and build a complementary bridge, which is a box girder bridge, in the same area. The third solution is to continue the existing rehabilitation programs to help strengthen the existing bridge. The four new designs and the continued rehabilitation were compared using a weighted matrix. The criteria that were used in the comparison are the Bridge Life Cycle Cost Analysis (BLCCA), heritage conservation, innovation, construction impact, traffic flow, and excess strength. The box girder obtained the highest score according to the weighted matrix and was thus chosen as the final design for Phase II of the project. A detailed design of both the superstructure of the bridge and its foundations will be performed using various codes and regulations. Structural drawings and construction plans will also be produced. ii Acknowledgements Special thanks to our technical advisor, Dr. Maria Anna Polak, for her contributions during Phase I of this project. In addition to providing technical guidance along the way, Dr. Maria Anna Polak also assisted in the brainstorming of possible design concepts for both the reconstruction of the Alexandra Bridge and the construction of a complementary bridge. iii Table of Contents 1 Introduction .......................................................................................................................... 1 1.1 Background ...................................................................................................................... 1 1.2 Project Requirements ....................................................................................................... 2 1.2.1 Demolition and Reconstruction ................................................................................ 2 1.2.2 Repurposing and Complementary Bridge ................................................................. 2 1.2.3 Retrofitting and Rehabilitation ................................................................................. 3 1.3 Scope of Work .................................................................................................................. 3 2 Design Constraints ............................................................................................................... 4 2.1 Heritage Conservation ...................................................................................................... 4 2.1.1 Design or Conceptual Values.................................................................................... 5 2.1.2 Materialistic Values .................................................................................................. 6 2.1.3 Holistic Contextual Values ....................................................................................... 6 3 Feasibility Analysis .............................................................................................................. 8 4 Bridge Life-Cycle Cost Analysis ......................................................................................... 9 4.1 Material and Construction Cost........................................................................................ 9 4.2 Maintenance Cost ........................................................................................................... 10 4.3 Economic Benefit ........................................................................................................... 10 4.4 Net Present Value ........................................................................................................... 11 5 Traffic Flow Impact ........................................................................................................... 11 5.1 Vehicular Traffic ............................................................................................................ 12 5.2 Light-Railway Transit Traffic ........................................................................................ 12 5.3 Pedestrian Traffic ........................................................................................................... 13 6 Construction Impact ........................................................................................................... 13 7 Conceptual Designs ........................................................................................................... 14 7.1 Cantilever Truss Bridge ................................................................................................. 15 7.1.1 Design Values ......................................................................................................... 15 7.1.2 Contextual Values ................................................................................................... 16 7.1.3 Traffic Flow ............................................................................................................ 16 7.1.4 Innovation ............................................................................................................... 16 7.1.5 Cost ......................................................................................................................... 16 7.1.6 Construction ............................................................................................................ 17 7.1.7 Strength ................................................................................................................... 17 7.2 Extradosed Bridge .......................................................................................................... 17 7.2.1 Design Values ......................................................................................................... 18 7.2.2 Contextual Values ................................................................................................... 18 7.2.3 Traffic Flow ............................................................................................................ 19 7.2.4 Innovation ............................................................................................................... 19 7.2.5 Cost ......................................................................................................................... 19 7.2.6 Construction ............................................................................................................ 20 7.2.7 Strength ..................................................................................................................