TECHNICAL ACTIVITIES Lunch and Learn Workshop DFI 44 Annual Conference on Deep Foundations with a conversation about effective communication. Employers cite communication skills as one of the most valued attributes when seeking and having employees interact with clients and coworkers. A group of DFI committee members will present effective communication skills, and we will discuss ways to cultivate them. Please join us on Tuesday, October 15, during the committee meeting lunch for the next installment of this light and fun workshop. AASHTO Update Submitted by Peggy Hagerty Duffy, P.E., D.GE, Hagerty Engineering and technical director of ADSC The 2019 American Association of State Highway and Transportation Officials (AASHTO) Committee on Bridges and Structures was held June 24-27 in Montgomery, Alabama. The committee includes a number of subcommittees, most notably the T-15 Subcommittee on Substructures and Retaining Walls. AASHTO provides specifications and guidance to all of the state departments of transportation within the U.S., and AASHTO specifications often affect the content of commercial specifications, as well. AASHTO receives guidance and support from the Federal Highway Administration (FHWA). Hagerty Duffy attended the meeting and participated in follow up discussions from the 2018 meeting concerning the development of a construction specification for soil nail walls. The ADSC-DFI joint committee on Anchored Earth Retention (AER) had provided feedback in 2018 on a proposed specification. Hagerty Duffy and Ed Laczynski, P.E., of Wagman Heavy Civil Construction and co-chair of the AER Committee, participated in a day-long meeting with subcommittee representatives in October 2018 to hash through specific issues with the specification. The lack of inclusion of Grade 100 bar in the specification was addressed but was found to be complicated by conflicts in the design specification for soil nail walls. This issue was restated during the meeting in Montgomery, and Hagerty Duffy agreed to inform the AER committee of the testing likely required to satisfy all of the requirements needed to bring the bar grade into both the design and the construction specification. It was noted that some state departments of transportation, including Ohio, do already recognize and accept the Grade 100 bar. Erik Loehr, Ph.D., P.E., of the University of Missouri, presented the results of his research on site characterization as it affects reliability. Loehr and his staff studied several code and design guidance procedures, including AASHTO, Eurocode, GEC-5 and the Missouri Department of Transportation method. Loehr concluded that to produce more accurate and practical design, some procedures should be slightly more complex. On the other hand, highly prescriptive methods were found to detract from the judgment of the We are continuing with our lunchtime workshop series during the th Mary Ellen Bruce Large, P.E., D.GE Director of Technical Activities [email protected] individual design engineer. AASHTO representatives noted that too much flexibility in site characterization program formulation can create administrative problems. Kathryn Petek, Ph.D., P.E., of Shannon and Wilson, also presented the results of a multi-phase study, where she led an exploration of large diameter open-end pipe (LDOEP) piles and the effects of plugging and other factors. Based on the findings, Silas Nichols, P.E., of FHWA, stated that FHWA would be expending effort to study large diameter foundation elements, particularly as they are used for construction-phase load testing. Scour was also discussed at the meeting and has been the subject of several internal meetings within AASHTO and FHWA. Attempts have been made to clarify that scour is not just a hydraulics/hydrology issue but also a geotechnical problem. AASHTO and FHWA will both continue to address this problem in an effort to quantify the effects of scour better and provide better guidance on design to prevent scour. Paul Axtell, P.E., Drilled Shaft Committee Chair New Geotechnical Engineering Circulars In May 2019, FHWA released two new publications related to deep foundations, as part of the series of geotechnical engineering guidelines called Geotechnical Engineering Circulars (GEC). The doc- uments are available for download from the FHWA website on the Bridges & Structures — Geotechnical page at www.fhwa.dot.gov/engineering/geotech. Printed copies of the publication are available for purchase from National Highway Institute at www.nhi.fhwa.dot.gov. GEC 10 – Drilled Shafts: Construction Procedures and Design Methods (FHWA-NHI-18-024) replaces the previous GEC-10 reference manual published in May 2010. This updated document provides recommended guidance for the selection, design, construction and acceptance of drilled shaft foundations for transportation structures. The updated document includes photos and figures that better illustrate recent developments in equipment and techniques for construction and testing, and revisions to design guidance and quality assurance procedures that better reflect evolution in construction procedures and changes in AASHTO specifications. The version that is currently posted online DEEP FOUNDATIONS • SEPT/OCT 2019 • 71
