Topics in Risk-based Design and Performance Evaluations of Structures

Abstract

This dissertation focuses on three topics that are critical to the development of a risk-based criteria for life-cycle design, analysis, and operation of power plant piping systems. One of three topics describes an exploratory study conducted on the application of risk-based load and resistance factor design approach to Section III of ASME Boiler and Pressure Vessel Codes for piping design. This study considers a straight pipe subjected to pressure and seismic load for service load D in class 2 and class 3 piping systems. The failure criterion needed to characterize the limit-state is considered as plastic instability.

The second topic in this dissertation relates to the analysis of coupled building-piping systems subjected to seismic loads. More specifically, it describes the effect of uncertainties in the modal properties of individual primary and secondary systems on the seismic response of coupled systems. Monte Carlo simulation and First-order reliability methods are used to study the problem in detail and identify critical aspects of this problem. Simple formulations are then developed for incorporation in a response spectrum method so that the design response is consistent with a desired probability of non-exceedence.

The third topic of this dissertation focuses on developing a probabilistic framework for structural condition assessment by using the frequency and mode shape data before and after degradation. While the results obtained using the proposed framework have shown considerable promise in applications to simple systems, significant room exists for improvement. Applications to additional examples with greater complexities are needed to identify the inconsistencies of the framework and develop improvements.