Fixity of members embedded in concrete

For concrete structures founded on piles, the length of pile embedment required to develop a condition to full fixity has a significant impact on the cost of the structure. The purpose of this research was to determine the pile embedment length required to provide reasonable assurance that a condition of full fixity exists for a pile embedded in the base of a concrete structure. A two-part study was performed on models of a cap-member-soil system and a cap-member system to evaluate the degree of rotational fixity associated with various pile embedment lengths and various pile types, including typical design conditions for HP 14X73 and HP 14X117 piles. The study results indicate that a pile embedment length equal to or greater than twice the pile depth or diameter is required to develop a condition approximating full fixity for a pile embedded in the base of a concrete structure.