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.

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: S_f-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