Structural redundancy and system reliability of highway bridges

Currently, bridges are designed so that the factored capacity of each of their structural members and components exceeds the load effects caused by a set of pertinent factored design loads or load combinations. Structural systems optimized to meet the member design criteria specified in current design standards and guidelines may not provide sufficient levels of redundancy to withstand an accidental single point failure or local damage resulting from intentional threats or other hazards. Highway bridges should have sufficient load path redundancy and capability to survive extraordinary events beyond the scope of conventional design criteria so that local structural damage or any single point of failure does not lead to progressive collapse. However, the quantification of redundancy is not fully formulated in current bridge standards and specifications. As a matter of fact, the load modifiers for redundancy in the current AASHTO LFRD Bridge Design Specifications and the system factors in the Manual of Bridge Evaluation were primarily based on very limited analyses and heavily relied on engineering judgment.;The objectives of this Dissertation are to develop a methodology to quantify the redundancy of bridge systems and to calibrate system factors that can be used in conjunction with design check equations to account for the redundancy of typical bridge configurations subjected to lateral load and vertical loads. (Abstract shortened by ProQuest.).