Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
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Soldier Rev B
| 8.3 HONG KONG In a document prepared by the Geotechnical Engineering Office (2006) the following methods are presented • Brinch Hansen (1961) for short rigid piles • Broms (1964) for fixed and free head piles in sand or clay • Poulos (1985) for two-layer soil As noted in the document, Kulhawy and Chen (1992) report Broms method tended to underestimate the ultimate lateral load by about 15 to 20 percent. The document states the above design approaches are simplified representations of pile behavior useful for obtaining a rough estimate of the likely capacity, and experience suggests that they are generally adequate for routine design It further suggests that if the design is likely to be governed by lateral load behavior, then load tests should be completed to verify design parameters. 279 A safety factor of 2.0 is allowed when lateral load tests are conducted and 3.0 when they are not. However, the design of a vertical pile to resist lateral loads is usually governed by limiting lateral deflection requirements. Two references are mentioned when implementing the methods on sloping ground, Bhushan (1979) and Siu (1992). The p-y method is mentioned in the document for assessment of nonlinear response in layered soils, but no guidance or recommendations are presented. 8.4 CHINA As reported in DFI (2012), the code in China is JGJ 94-4 and entitled Technical Code for Building Foundations The summary contained herein is based on a description of the code presented by DFI (2012), and is assumed to be applicable to buildings, but not necessarily intended for transportation structures, based on the title. The actual Chinese code could not be obtained and reviewed for this study the information presented herein is based on the summary in other sources (DFI 2012). The code requires that for Class I buildings a static lateral load testis required to determine the allowable lateral pile capacity. Class I buildings are classified as important residential and industrial structures The lateral capacity is taken as the load corresponding to a deflection of 10 mm (0.38 in) for precast concrete, steel, and bored piles with reinforcement ratios greater than 0.65 percent. For buildings sensitive to horizontal movement the limit is decreased to mm (0.24 in. It is not clear based on available information if the load testing is performed to failure or includes determination or verification of the ultimate lateral pile capacity it is assumed that the tests are not carried to failure or ultimate capacity based on the indication that the testing is required for determining the allowable lateral pile capacity (DFI 2012), The safety factors used in conjunction with the load testing are not known based on available information at the time of this study. When lateral load tests are not performed, for non-Class I buildings, lateral capacity is determined from empirical equations, which are not included in the referenced DFI document. There are separate formulas for elements controlled by deflection or structural capacity. Pile group effects are also accounted for in design. Download 6.03 Mb. Share with your friends:
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