Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
Block 9 – Perform Analyses for Laterally Loaded Single Pile
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| Block 9 – Perform Analyses for Laterally Loaded Single Pile The next step in the design process involves analyzing the preliminary foundation type, size and length selected previously for Geotechnical Strength, Structural Strength, Service, and Extreme Event Limit States. To perform this step, the designer computes deflection and rotation at the head of a deep foundation element and the maximum bending moment and shear force within the deep foundation element. The designer also determines the nominal bending moment resistance of the deep foundation element (this is the moment at which a plastic hinge will develop in the foundation. These analyses are usually performed with the use of software programs. The details of various methods for performing these analyses are discussed in Chapter 6 for individual lateral pile analyses, Chapter 7 for pile group analyses, and Chapter 11 for structural analyses. This step must include consideration of the axial loads. The axial loads will influence the maximum bending moment capacity as well as the amount of deflection that occurs under lateral loading. Typically, the designer selects the pile/shaft length and performs analysis on a trial-and-error basis. Some computer programs can perform this step internally and produce a summary of pile lengths versus deflection (or other criteria) from which a minimum embedment length can be determined. This iterative procedure is repeated for different size piles or shafts (diameter, width, or pile section) to develop the most appropriate design. However, the designer will need to determine if a greater pile/shaft penetration is needed to satisfy axial load demand and foundation settlement criteria. For drilled shafts or CFAs, atrial longitudinal reinforcement must be selected for analysis. Atypical initial value is a longitudinal reinforcement of about 1 percent of the overall shaft cross sectional area (Brown et al. 2010; Brown et al. 2007). Engineering judgment and experience maybe helpful in assessing reasonable reinforcement amounts, especially for applications with relatively high lateral loads or bending moments. Download 6.03 Mb. Share with your friends:
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