Chance Technical Design Manual

BROMS’ METHOD FOR SHORT PILES IN CLAY (ENERGY STRUCTURES, INC., 1994) FIGURE 5-21

Full scale seismic tests of helical piles were performed in 2016 at the University of California - San Diego shake table. Several different simulations were performed, including the Northridge and Takatori seismic events. Various helical pile configurations were installed in the test box, including square and round shaft piles of varying diameters. The reader is referred to numerous documents published about these studies (Cerato et al., 2017, Elsawy et al., 2017 and 2019. 5.7.3 ADDITIONAL COMMENTS The lateral capacity of round shaft (RS) helical piles and an chors is greater than that of square shaft (SS) because of the larger section sizes. Typical pipe diameters of 2-7/8” (73mm), 3-1/2” (89 mm), and 4-1/2” (114 mm) OD are used for Chance® round shaft helical piles. As shown in Design Example 8-13 in Section 8, enlarged shaft sections are used for certain applica tions. From a practical standpoint, the largest diameter helical pile available from Hubbell Power Systems, Inc., is 10-3/4” di ameter, but larger shaft diameters are available on a project specific basis. As previously noted, there are several other methods used to analyze the lateral capacity of pile shafts. Murthy (2003) also presented a direct method for evaluating the lateral behavior of battered (inclined) piles.

GRADE BEAM

P p

P a

DESIGN METHODOLOGY

SOIL: LOOSE SAND

FIGURE 5-21 EARTH PRESSURE ON A GRADE BEAM

EARTH PRESSURE ON A GRADE BEAM FIGURE 5-22

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