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

Purpose and Background

Spread footings are often under-utilized in comparison to the costlier deep foundation systems. This workshop will include discussions about spread footings on soil and rock. The workshop will discuss the development of the bearing resistance chart that permits consideration of several limit states (settlement, limiting eccentricity, and bearing resistance) in one convenient format. Other limit states such as sliding will also be discussed. The presentation will be indexed to the latest (2020) version of the Bridge Design Specifications (BDS) based on 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 spread footings. The 2020 version of AASHTO LRFD BDS includes new information on analysis of spread footings such as the construction-point concept and implementation of the SE load factor which accounts for the uncertainty in prediction of settlements. Information on Protection Index concept from AASHTO’s latest (2020) Guide Specification for Service life design will also be presented.

Benefits and Learning Outcomes

Benefits

• Gain knowledge on latest design procedures for spread footings on soil and rock
• Understand the construction-point concept
• Recognize the uncertainty in settlement predictions and use of SE load factor
• Examine the possibilities and benefits of improved communications between geotechnical and structural specialists for spread footing design

Learning Outcomes

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

• Use the proper terminology related to analysis of spread footings using the LRFD methodology.
• Categorize failure modes of spread footings on soil and rock into applicable geotechnical limit states.
• Discuss sliding, limiting eccentricity, bearing resistance, and settlement aspects of spread footings on soil and rock.
• Explain the concept of bearing resistance chart and its development.
• Apply the bearing resistance chart for sizing spread footings.
• Explain the construction-point concept.
• Explain the basis and application of the SE load factor to account for uncertainty in settlement predictions.
• Estimate reliability based differential settlement values.
• Explain the new AASHTO Guide Specification provisions for considering effects of material deterioration on spread footings.

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, general practitioners
General civil engineering specialists
Agencies/owners
General Practitioners

Outline

Using a collaborative and interactive learning approach, this virtual workshop will help you understand: (a) the analysis for spread footings on soil and rock, and (b) the latest AASHTO LRFD guidelines for spread footings including the construction-point concept and the SE load factor. 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) and/or a reflection (e.g., reading) assignment.

DAY 1

• Introductions
• Terminology, pressure distributions, and limit states
• Sliding stability
• Limiting eccentricity (overturning) stability
• Bearing stability
• Overall (global) stability)
• Settlement
• Bearing resistance and settlement chart
• 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
• Example: Sizing a footing using a bearing resistance chart
• Construction-point approach
• Reliability of estimated settlements and the SE load factor
• Differential settlement: Sf-0 and NPEC approaches
• Definition of rock and rock mass
• Example: Sizing a footing on rock
• Considerations for extreme events
• Material Deterioration: AASHTO Guide Specification
• Closure and references
• Review of Day 2 and full workshop
• Interactive Question and Answer (Q&A) session
• Adjourn

How to Earn your CEUs/PDHs

This course is worth .4 CEUs / 4 PDHs. 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.

How do I convert CEUs to PDHs?

1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]