| In order to assess the reliability of a structure, it is necessary to develop theoretical models for evaluating the uncertainties inherent in the structure as well as in the external loading environment.;Reliability-based analysis and design procedures are usually aimed at design of individual components. In this thesis, structural systems are analyzed using methods of system reliability theory for establishing the relationship between the reliability of the individual components within the system and the reliability of the whole system.;It is generally assumed that the system or its components are either in a functioning state or in a failure state. The reality of structural systems, however, is that they experience a wide range of performance levels ranging from perfect functioning to total failure (i.e., multistate structural systems).;The purpose of this thesis is threefold: (1) to study the methods of system reliability theory as they are applied to structural systems. These methods are applied to multistate systems for analysis and design using reliability-based approaches including system safety requirements with regard to serviceability (i.e., excessive deformations) and ultimate limit states (i.e., complete structural collapse); (2) to optimize structures using both deterministic and reliability-based concepts; and (3) to develop a methodology for evaluating the effects of damage on both the redundancy and reliability of existing structures. This methodology uses both deterministic and reliability-based frameworks, and accounts for the various stages of damage to the structural components and the overall structural system. A strategy for relating the amount of damage to the level of redundancy and reliability of structures is proposed.;Several sample problems are presented throughout this thesis to emphasize the advantages of the application of system reliability theory to multistate structural systems. In addition, the reliability of existing bridge structures is investigated for several damage models, including corrosion models and models where failure of one or more structural bridge members is simulated. In this context, the effects of damage on bridge redundancy and reliability are calculated as the bridge undergoes progressive stages of deterioration. |
