Tamer Osman, P.E., Senior Project Manager, Delta Engineers, Architects & Land Surveyors, PC

1. Simple, Economic and
Fast Solution for Bridge
substructures.
Innovative Precast System
For Short Spans and Low Volume Bridges

2.  Year Built : 1950
 Primary Owner : Town
 Steel Stringers
 Timber Deck
 Span Length : 30 feet
 Out to Out Width : 23.6 feet
 Skew Angle : 30 Degrees
 Abutment Height : 14 Feet
 AADT : 57
 Posted for 5 Tons
 Founded on Spread Footers
Bridge Data
Innovative Precast System
For Short Spans and Low Volume Bridges
Case Study in NY

3. Existing Conditions
Innovative Precast System
For Short Spans and Low Volume Bridges

4. Bridge Replacement Alternatives
 Four Sided Structure
 Three Sided Structure ( Box or Arch)
 Integral Abutment with Prestressed Beams Superstructure
 Non Conventional System
Innovative Precast System
For Short Spans and Low Volume Bridges

5. Types of Concrete Abutments
 Cantilever Abutments
 Integral Abutments
 Abutments Founded on Piles
 Non Conventional System
Innovative Precast System
For Short Spans and Low Volume Bridges

6. Cantilever Abutments
 Abutment Stem
 Abutment Backwall
 Abutment Footings
Design Forces
Main Components
 Earth Lateral Pressure
 Loads From Superstructure
 Bearing Capacity
Innovative Precast System
For Short Spans and Low Volume Bridges

7. How it Works ?
Factors Affect the Footing
Dimensions:
 Toe and Heel Widths are
Determined by The Sliding and
Overturning Forces
 The Footing Area is Determined by
the Bearing Capacity Constraints
 The Footing Thickness and
Reinforcement are
Determined by The
Base Pressure
(Shear and Flexure)
Innovative Precast System
For Short Spans and Low Volume Bridges

8. Factors Affect the Stem
Dimensions:
 Stem Thickness is Determined by
Flexural forces Resulted from Earth
Pressure
 Reinforcement is Determined By the
Flexural Forces
 Bridge Seat Requirements May
Determine the Thickness of the Stem
Which Results in Excessive Concrete
Volume
Innovative Precast System
For Short Spans and Low Volume Bridges

9. Cantilever Abutments
 Conventional System, Easy To
Construct and Design
 Suitable For Most Soil Conditions
(Rock or Shale )
 Can be Used With Any Skew
Cons
Pros
 Not Suitable For Poor Soils
 Requires Large Amount of Concrete
 Requires Large Quantity of Reinforcement
 Requires Large Volume of Excavation
 Requires a Deck Joint
Innovative Precast System
For Short Spans and Low Volume Bridges

10. Integral Abutments
 Abutment Stem
 Deep Foundations (Piles)
Main Components
Design Forces
 Earth Lateral Pressure
 Loads From Superstructure
 End Bearing Capacity or
Skin Friction Capacity
Innovative Precast System
For Short Spans and Low Volume Bridges

11. How it works ?
Factors Affect the Abutment
Dimensions:
 Stem Thickness is Determined by
Flexural forces Resulted from Earth
Pressure
 Reinforcement is Determined By the
Flexural Forces
 Bridge Seat Requirements May
Determine the Thickness of the Stem
Which Results in Excessive Concrete
Volume
Innovative Precast System
For Short Spans and Low Volume Bridges

12. Integral Abutments
 NYSDOT Preferred Abutment Type
 Jointless Bridge System
 Less Concrete and Reinforcement Than
the Gravity Abutments
 Fast Construction Time Compared to
Gravity AbutmentCon
s
Pros
 Not Suitable For All Soil Conditions
 Not Suitable For Large Skews
 Requires Deep Foundation
 Costs More Than Gravity Abutments
Innovative Precast System
For Short Spans and Low Volume Bridges

13. Precast Abutment System
 Pre-Cast Concrete Cap
 Pre-Cast Concrete Lagging
 Pre-Cast Concrete Footings
 H-Piles Embedded In Concrete
Footings
Design Forces
Main Components
 Earth Lateral Pressure
 Loads From Superstructure
 Soil Parameters
Innovative Precast System
For Short Spans and Low Volume Bridges

14. How It Works
The System Consist of The Following:
 Pre-Cast Lagging: Designed to
Retain The Soil and Resist Lateral
Forces from Soil
 H-Piles: Designed to Carry the
Cap Beam Which Carries The
Super Structure
 Precast Footings: Designed to
Distribute the Load to The Bearing
Stratum
 Mechanical Couplers: Connects
The Units Together
Innovative Precast System
For Short Spans and Low Volume Bridges

15. Design Forces
Factors Affect the Footing Dimensions:
 Toe and Heel Dimensions are
Determined by The Sliding and
Overturning Forces
 The Footing Area is Determined by the
Bearing Capacity Constraints
 The Footing Thickness and
Reinforcement are Determined by The
Base Pressure (Shear and Flexure)
Innovative Precast System
For Short Spans and Low Volume Bridges

16. Precast Abutment System
 Simple and Flexible Design
 Easy To Handle and Install
 Small Sections Compared to
Conventional Design
 Fast Construction Time
 Economic Design
 Concrete Cap To Accommodate Bridge Seat Requirements
 Can Be Installed with Mid Size Excavator
Cons
Pros
 Aesthetics
Innovative Precast System
For Short Spans and Low Volume Bridges

17.  Pre-Cast Abutment System
 Pre-Stress Pre-Cast Beams
The Preferred Alternative
Innovative Precast System
For Short Spans and Low Volume Bridges

18. Construction Phase
Innovative Precast System
For Short Spans and Low Volume Bridges

19. Questions ?
Innovative Precast System
For Short Spans and Low Volume Bridges