Building better confidence intervals for the resistance factor in LRFD

Date

2015-12

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Abstract

Engineers employ the LRFD model system in the planning and development of

structures (e.g. bridges, highways, buildings). The system takes into account the load

the structure will bear and the resistance of the structure against that load. Of interest

in the LRFD system is the resistance factor (φ) that affects the resistance. Samples are

collected to estimate φ, but the estimate (φ ̂ ) has typically been treated as a

deterministic number; when instead, it should be viewed as a random variable.

This thesis examines the performance of one method of proposed confidence

intervals for φ ̂ , investigates the sampling distribution of φ ̂, and proposes

improvements upon the existing method. A bootstrap simulation process is employed

to evaluate the performance of the proposed method (nonparametric and parametric)

through the metrics of coverage and relative interval length. Additionally, another

simulation is used to determine the distribution of the estimator (φ ̂). Finally, remedial

measures for the original interval method are proposed, implemented, and investigated

via simulations.

Description

Keywords

LRFD, Confidence intervals, Bootstrap simulation

Citation