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Research ThrustsInfrastructure Diagnostics and Monitoring Reliable diagnostic and monitoring methods are essential to the durability and security of the national infrastructure. Modern construction practices create challenging monitoring needs as critical components are hidden, and yet adequate performance must be verified during construction, or over many decades. CEE researchers respond to this challenge with notable contributions, including devising novel thermal sensors to ensure concrete integrity in drilled shaft constructions, and refinement of testing methods such as Statnamic to verify load carrying capacity. Further, design and construction methods involving post grouted drilled shafts have been developed that enhance the end bearing performance while providing a mechanism of monitoring their quality. As thousands of highway bridges along Florida's coasts are susceptible to severe saltwater corrosion, CEE investigators have developed advanced analysis methods for assessing the penetration of concrete by aggressive ions, and electrochemical techniques to determine the performance of corrosion resistant materials for future construction. Corrosion can also attack critical high strength steel tendons in advance design bridges, and CEE research has developed vibrational methods and spectral analysis techniques for condition assessment. This innovation provides a means by which once invisible damage can now be detected prior to catastrophic failure, and is being now applied to major bridges nationwide. Subsurface Infrastructure The University of South Florida is heavily involved in the design, construction, and quality assurance of subsurface infrastructure in the State as well as the country. As this area of continuing research often involves highway bridges, it can be linked to each of the four groups within the Department of Civil and Environmental Engineering (CEE). However, those researchers within CEE involving structures, materials, geotechnics, and water resources are most regularly requested to provide assistance in solving a wide range of problems with structural elements rarely seen by the public. To this end, cost-saving design approaches have been developed and field implemented that were subsequently adopted into the State Construction Specifications. Further, new methods of assuring foundation integrity, monitoring the performance, verifying the capacity as well as analyzing the respective data have been developed and disseminated to the engineering society. With regard to existing deteriorating infrastructures, CEE researchers have paved pioneering inroads into new methods of rehabilitating damaged concrete foundations using fiber-reinforced plastics that show great promise with dramatic potential cost savings. Advanced Structural Materials The propensity of traditional construction materials to deteriorate in aggressive environments has led to worldwide interest in alternative materials. Among these, fiber reinforced polymers (FRP) show particular promise because of their inherent corrosion resistance, light weight, and high strength to weight ratio. For well over a decade, USF has pioneered research to evaluate their long-term performance in a marine environment. Other studies have examined new FRP applications such as settlement repair of masonry walls or strengthening steel girders. Current studies include investigations to evaluate the application of FRP in repairing corrosion-damaged piles driven in tidal waters. Both laboratory testing and full-scale field demonstration are part of the on-going study. Investigations are also being undertaken to examine other new materials such as high performance steel and concrete. The goal of these studies is to ensure safe and reliable use of these new materials. Due to continuous modifications of EPA regulations, state and national codes have to be re-examined and re-assessed for protecting durability of the structural concrete. Critical Infrastructure Rehabilitation Florida’s sub-tropical climate and long coastline make marine structures vulnerable to corrosion damage. The problem is particularly severe in jacketed piles where the extent of corrosion is hidden and cannot be detected during routine maintenance inspection. The structural adequacy of such piles was a great concern to highway authorities. USF researchers conducted several laboratory studies to investigate this problem. Observed damage was carefully reproduced in scale model tests to allow systematic investigation of the relationship between corrosion, residual capacity and repair. These investigations led to new methods for accelerating corrosion, the development of user-friendly software and innovative testing procedures to allow simulation of sustained loads. On-going studies are evaluating panel deck bridges that have experienced unexpected local failures. Investigations include field assessment, non-destructive testing and numerical modeling. The goal is to develop a rational method for prioritizing replacement of over 100 panel deck bridges. Engineering Materials Durability The Civil and Environmental Engineering (CEE) Department has an active program for assessing and improving the durability of engineering materials for our national infrastructure. A major component of this work investigates the mechanism of corrosion of traditional and advanced metallic materials in reinforced concrete, post tensioned assemblies, and soil and water systems under the aggressive service environments encountered in Florida. The work encompasses understanding of fundamental electrochemical aspects of corrosion, determining the performance of modern concrete formulations in actual service conditions, and forecasting the economic impact of engineering alternatives. Advanced electrochemical and structural diagnostic methods are developed as well. A combination of extensive field surveys, experimental research and sophisticated computer models is regularly applied to improve design and corrosion protection methods for enhanced durability. Special focus is placed on studying cementitious systems and their role in extending the life span of structural concrete under different service conditions. This area of research examines the significance of different cementitious/pozzolanic systems, their microstructural characterization and their impact on the physical, mechanical and chemical properties of concrete. Mechanisms of failure are studied using advanced phase transformation techniques. Research also addresses microstructure-property relationships in high performance concrete with chemical admixtures to retard chloride ingress and environmental degradation in the substructure of marine bridges. Innovative Structural Design Concepts Potential gains from new materials and technologies can be best realized through innovative design and testing. Over the past decade, USF has conducted several studies to advance the practice of engineering. For example, full-scale tests were conducted to evaluate the interface bond in seal slabs used in cofferdam construction. Resulting changes in design specifications have led to more economical construction. New concepts, such as double composite construction have been developed that help lower costs and enhance the competitiveness of steel bridges. A new modular FRP section was proposed that eliminates the need for connections. This system allows rapid assembly of emergency shelters in disaster-struck regions since it only requires hand tools and unskilled labor. On-going studies are evaluating the application of cold bending to fabricate curved steel girders, currently disallowed in bridge construction. The goal of the research is to establish the necessary framework that will allow its eventual acceptance by the bridge community. |
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