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# Segmental Bridge Abutment Design Using Solid Finite Elements

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### Segmental Bridge Abutment Design Using Solid Finite Elements

1. 1. Barritt Lovelace, PE WSB and Associates May 25 th , 2011 Segmental Bridge Abutment Design Using Solid Finite Elements
2. 2. Lafayette Bridge <ul><li>Spans the Mississippi River east of Downtown St. Paul </li></ul>
3. 3. Project Description <ul><li>Two options were designed </li></ul><ul><ul><li>Segmental Concrete </li></ul></ul><ul><ul><li>Steel Box Girder </li></ul></ul><ul><li>WSB Teamed with Figg Engineering Group to form the concrete design team </li></ul>
4. 4. Abutments <ul><li>Resists vertical loads from Superstructure </li></ul><ul><li>Resists lateral loads from earth pressure </li></ul>
5. 5. Two Dimensional Analysis <ul><li>Typical Design Method </li></ul><ul><ul><li>Loads from superstructure are assumed to be equally distributed along abutment </li></ul></ul><ul><ul><li>Pile loads are determined by calculating the neutral axis of the structure </li></ul></ul>
6. 6. Segmental Bridge Loads <ul><li>Segmental concrete bridges typically have only two to three bearings </li></ul>
7. 7. Three Dimensional Approach <ul><li>Produces large concentrated loads </li></ul><ul><li>Abutments need to be analyzed in three dimensions to determine distribution </li></ul>
8. 8. Finite Element Analysis <ul><li>Definition </li></ul><ul><ul><li>The finite element method is a numerical technique for finding approximate solutions of partial differential equations as well as of integral equations. </li></ul></ul><ul><ul><li>In the FEM, the structural system is modeled by a set of appropriate finite elements interconnected at points called nodes. </li></ul></ul>
9. 9. Finite Element Analysis
10. 10. Solid Finite Element Analysis
11. 11. Advantages of 3-D Analysis <ul><li>Improved accuracy </li></ul><ul><li>Eliminates variability in pile loads </li></ul><ul><li>Reduces pile quantities </li></ul><ul><li>Capacity to more accurately place piles </li></ul><ul><li>Ability to integrate the wingwall geometry </li></ul>
12. 12. Summary of Results
13. 13. Conclusions <ul><li>Very effective for shorter abutments </li></ul><ul><li>More accurate for all abutment heights </li></ul><ul><li>Potential to provide economical designs on all types of bridges and abutments </li></ul><ul><li>With better computer hardware these types of designs will be more common </li></ul>
14. 14. Project Team Members <ul><li>MnDOT </li></ul><ul><li>Manjula Louis, Kevin Western, Paul Kivisto </li></ul><ul><li>FIGG </li></ul><ul><li>Russ Call, Mike Keller, Chris Burgess </li></ul><ul><li>WSB </li></ul><ul><li>Barritt Lovelace, Sabri Ayaz, Jim Archer, </li></ul><ul><li>Dave Vincent, Brad Robinson </li></ul>