Abstract
This paper presents a practical framework to characterize the model uncertainty for the bearing capacity of strip footings under positive combined loading. The method of calculation recommended by Eurocode 7 is considered. The model uncertainty is usually represented in terms of the probability distribution of a model factor, which is defined as the ratio of the measured capacity (q(u)_(exp)) to the calculated capacity (q(u_calc)). The key contributions in this paper are: (1) the model factor for Eurocode 7 is a function of input parameters, (2) this dependency can removed using a regression equation f, but the number of load tests required for regression exceeds what is available in the literature. However, FELA is good enough to replace load tests in this critical regression step, (3) the model factor for FELA can be characterized using available limited load tests-it is a lognormal random variable with mean=1.03 and standard deviation=0.087, and (4) the model factor for a modified Eurocode 7 capacity q'(u_cal)c=q(u_calc)xf is no longer a function of input parameters-it is a lognormal random variable with mean=1.04 and standard deviation=0.11.