Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
STRUCTURAL DESIGN AND PERFORMANCE
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Soldier Rev B
| 11 STRUCTURAL DESIGN AND PERFORMANCE 11.1 OVERVIEW This chapter provides general guidance for the structural design of deep foundation elements once the load effects imposed on the foundation elements have been determined through analysis. The structural design of the foundation elements is performed in accordance with the AASHTO LRFD Bridge Design Specifications (AASHTO 2014). Laterally loaded piles and drilled shafts experience axial, bending and shear load effects simultaneously and are designed to account for the interaction of these load effects. The load effects are the result of load combinations applied to the superstructure and substructure which are ultimately transferred to the foundation elements. Load combinations are determined for each of the applicable Limit States (service, strength, or extreme events) in accordance with the load combinations dictated by the AASHTO specifications. For guidance regarding Limit States, loads, load factors and load combinations refer to Chapter 4 of this manual. Once the appropriate applied force effects from the load combinations have been determined at the top of the foundation, analysis of the foundation element or group of foundation elements is performed to determine the force effects applied to the specific foundation element being designed. For guidance regarding the analysis of laterally loaded single piles/shafts and groups of deep foundation elements refer to Chapters 6 and 7 of this manual, respectively. Force effects vary along the length of the foundation element. The foundation element can be designed to resist the governing force effects, or can have different designs along the length of the element. Transition zones between design sections should always be designed for the more severe combination of force effects. Typical foundation elements are constructed from reinforced concrete (prestressed or conventionally reinforced) and structural steel. The design specifications for these materials are in AASHTO (2014) Section 5 – Concrete Structures, and Section 6 – Steel Structures, respectively. Detailing of the connection between the foundation element and the substructure must be consistent with the analysis assumptions regarding fixity as this connection is used to determine the load effects in the foundation element. Much of the information in this section has been extracted directly and/or adapted from Hannigan et al. (2016) for driven piles, and from Brown et al. (2010) for drilled shafts. Download 6.03 Mb. Share with your friends:
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