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	A Conference on Architectural Surety
	Assuring the Performance of Buildings and Infrastructures
	PROCEEDINGS

Issues in Civil Infrastructure Systems Engineering

Emin Aktan and Arthur Helmicki

University of Cincinnati

ABSTRACT

Integrative, inter-disciplinary and multi-institutional research and technology development, conducted by university-government-industry partnerships, are deemed essential for innovation which is necessary to sustain civil infrastructure systems (CIS). The writers approached highway bridges both as representing a critical component of the transportation system, and also a generic component within a CIS. Research was designed to further explore policy, strategy and tactics related to research, education and practice, offering potential for innovating CIS engineering. Actual operating bridges were used as field-test specimens, in collaboration with federal and state DOT engineers, consultants, contractors and suppliers. Technologies offering significant experimental and analytical capabilities have been explored, integrated, customized and demonstrated. The experimental tools include modal analysis and instrumented monitoring. When applied in the context of structural identification, these experimental tools lead to an objective identification of damage, and to a detailed analytical characterization of a bridge in terms of a field-calibrated finite-element model. The organizational and other non-technical barriers obstructing the implementation of advanced technologies have been understood as well. The structural identification concept appears to be the key for integrative research and applications, and offers promise to bring us closer to a renaissance in CIS engineering and practice. In the case of specific technical accomplishments, valuable insight has been gained regarding steel-stringer bridges which make up the most common bridge type in the USA. Currently we follow empirical guidelines in new or renewal design decisions regarding girder sizing, spacing and camber, deck thickness and reinforcing details, design of the interface between the deck and the girders, cross-frame sizing, spacing and their girder-connection details, bearings, abutments and sub-structure. The researchers have accurately measured the loading environment, the structural properties and the responses to load of eight steel-stringer bridges. It was possible to express global condition objectively based on bridge flexibility which could be measured by either a dynamic (modal) test or by instrumented monitoring under controlled truck-loading. Three of the test bridges were subjected to significant truck super-loads, another was subjected to controlled damage scenarios, and yet another was monitored through fabrication and construction. The observations and a synthesis of the data led to an insight on the life-cycle behavior of this most populous bridge type, and a type-specific maintenance management strategy has been formulated.