Multiple resistance factor methodology for service limit state design of deep foundations using a "t-z" model approach
Conference
Roberts, LA, Gardner, BS, Misra, A. (2008). Multiple resistance factor methodology for service limit state design of deep foundations using a "t-z" model approach
.(178), 74-81. 10.1061/40971(310)9
Roberts, LA, Gardner, BS, Misra, A. (2008). Multiple resistance factor methodology for service limit state design of deep foundations using a "t-z" model approach
.(178), 74-81. 10.1061/40971(310)9
For the AASHTO Load and Resistance Factor Design (LRFD) of deep foundations, resistance factors must be applied to the calculated nominal load capacity to determine the nominal resistance of the foundation. The deep foundation is adequate if the nominal resistance is greater than the calculated factored load. In most current methods, the side and tip resistance are calculated separately and are added to determine the nominal capacity of the foundation. When using the "t-z" model, however, the percentage of the design load carried by side resistance and tip resistance is known at any applied load. Therefore, it is beneficial to consider how the uncertainties in the side and tip resistance model parameters each affect the uncertainty in the total load capacity of the foundation. In this paper, resistance factors have been calculated for the design of deep foundation systems based on side and tip resistance. The model parameters are back-calculated using actual load test data and the variability in the side and tip parameters is examined separately in a series of Monte Carlo simulation analyses. Histograms of the deep foundation load capacity, corresponding to an allowable total displacement, are developed for the simulations and analyzed to calculate separate side and tip resistance factors. Copyright ASCE 2008.
