Accession Number : ADA181310

Title :   Creep in Prestressed Concrete Piles: A Comparison of the Direct Solution Method, the Incremental Time Step Method, and the Curve Fitted Equation Method of Calculating Time Dependent Losses in Hawaiian Aggregate Prestressed Concrete Piles.

Descriptive Note : Final rept.,

Corporate Author : ARMY MILITARY PERSONNEL CENTER ALEXANDRIA VA

Personal Author(s) : Hirata,Stacey K

PDF Url : ADA181310

Report Date : May 1987

Pagination or Media Count : 153

Abstract : Three methods to calculate creep strains were examined and their results were compared against the strains observed in 55 foot long, 16.5 inch octagonol, prestressed concrete piles. The direct solution method involved the straight forward application of the creep strain equation. The incremental time step method used the creep strain equation and accounted for the stress reduction in the prestressing steel over each time interval. The curve fitted equation method involved curve fitting the observed creep strain to the hyperbolic, exponential, and power equation forms by the method of least squares. Two different creep and shrinkage equation sets were used in the direct solution and incremental time step methods. The American Concrete Institute's recommended equations with correction factors were used as one set. The other set consisted of empirically derived equations of the hyperbolic form which resulted from a companion creep study involving standard test cylinders. The direct solution method using the local test cylinder's empirically derived creep and shrinkage equaitons produced reasonably accurate predictions of strain for the cost.

Descriptors :   *CREEP, *CREEP TESTS, *PILE STRUCTURES, *PRESTRESSED CONCRETE, CONCRETE, CORRECTIONS, CURVE FITTING, CYLINDRICAL BODIES, EQUATIONS, FORWARD AREAS, LEAST SQUARES METHOD, VISCOUS FLOW, LOSSES, REDUCTION, SHRINKAGE, STRESSES, TEST EQUIPMENT, TIME, TIME DEPENDENCE, TIME INTERVALS, MATHEMATICAL ANALYSIS, PHYSICAL PROPERTIES, SEEPAGE, VOIDS, CHEMICAL PROPERTIES, PASTES, CURING

Subject Categories : Ceramics, Refractories and Glass
      Construction Equipment, Materials & Supplies
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE