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INSTRUCTOR: 
Naresh Samtani, Ph.D., P.E., D.GE, F.ASCE

Purpose and Background

Foundations for bridges and approach structures should be designed so that their movements will not damage the bridge superstructure and associated structures such as abutments and approach slabs. Various aspects of movements that should be considered in the design of bridges include (a) the effect of uneven (differential) settlement between various support elements, (b) the rotation and horizontal movements of the foundation system affecting movements at the bridge-seat level; (c) movements due to material deterioration; and (d) serviceability problems near a bridge abutment and approaches. The presentation will be based on latest (2020) version of the Bridge Design Specifications (BDS) and the Load and Resistance Factor Design (LRFD) platform of the American Association of State Highway and Transportation Officials which is a key component of Federal Highway Administration (FHWA) guidelines for this topic. Information on Extended Service Life (ESL) and Protection Index (PI) concepts from AASHTO’s latest (2020) Guide Specification for Service life design will also be presented.

Primary Discussion Topics

Day 1

• Terminology and definitions for bridge structures and foundations
• Foundation types
• Abutment types
• Modes of foundation movements
• Differential movements and angular distortions
• Effects of foundation movements at bridge seat level
• Effects of movements of approach structures on abutments
• Tolerable limits of foundation movements
• Construction-point approach

Day 2

• The SE load factor and its development
• Example: Application of the SE load factor
• Evaluation of differential settlements: Sf-0 and NPEC Approach
• Example: Incorporation of Foundation Movements in Bridge Design
• Materials Deterioration and Extended Service Life Concepts
• Protection Index Concepts
• References

Benefits and Learning Outcomes

Upon completion of this course, you will be able to:

• Recognize the interaction between foundations and bridge structures.
• Explain the modes of foundation movements.
• Comprehend the construction-point approach.
• Discuss the effect of foundation movements on bridge superstructures.
• Explain the effect of movement of approach structures on abutments.
• Identify and understand the tolerable movement criteria.
• Comprehend the SE load factor and its application.
• Identify the various provisions related to foundation movements of the AASHTO LRFD Bridge Design Specifications
• Explain the new AASHTO Guide Specification for Service Life Design.
• Foster a better understanding of the serviceability effects of foundation movements by structural and geotechnical specialists involved in bridge designs.
• Recognize potential problems for bridge structures related to foundation movements.
• Explain the need to have enhanced understanding of the interaction between bridge superstructure and foundations.
• Examine the possibilities and benefits of improved communications between geotechnical and structural specialists for bridge foundation design

Assessment of Learning Outcomes

Students' achievement of the learning outcomes will be assessed via a short post-assessment (true-false, multiple choice and fill in the blank questions).

Who Should Attend?

Geotechnical specialists, structural specialists, bridge designers

Outline

Using a collaborative and interactive learning approach, this virtual workshop will help you understand: (a) the types of foundation movements and the uncertainties associated with them, (b) the construction-point concept and the SE load factor, and (c) the effects of foundation movements on bridge superstructure and appurtenant structures. The workshop will help you assimilate these crucial considerations through active participation by frequent interactions throughout the workshop and real-time expert feedback. The interactions will facilitate a better understanding of the nuances of the various design procedures which would help you avoid costly design errors in real-world projects. In between the two live sessions, attendees will independently work on an application (e.g., exercises) or a reflection (e.g., reading) assignment.

Day 1

• Introductions
• Typical components and terminology for bridge structures
• Types of bridge foundations and abutments
• Modes of foundation movements
• Effect of foundation movements on bridge superstructures
• Effect of movements of approach structures on abutments
• Tolerable values of movements
• Construction-point approach
• Review of Day 1
• Interactive Question and Answer (Q&A) session
• Assignment of homework
• Adjourn

Day 2

• Roadmap for Day 2
• Review of homework assignments and recap of Day 1
• AASHTO LRFD Articles relevant to foundation movements
• The SE load factor
• Example Problem: Application of the SE Load Factor
• Differential settlement: Sf-0 and NPEC Approaches
• Example: Incorporation of Foundation Movements in Bridge Design
• Material Deterioration: AASHTO Guide Specification for Service Life Design
• References
• Closure
• Review of Day 2 and full workshop
• Interactive Question and Answer (Q&A) session
• Adjourn

How to Earn your CEUs/PDHs

This online course is worth .4 CEUs/4 PDH’s. To receive your certificate of completion, you will need to complete a short on-line post-test and receive a passing score of 70% or higher within 30 days of the course.