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This Symposium Volume reports on the latest advancements related to the various facets of modeling and performance assessment of concrete structures. The volume contains 10 papers that were presented at the ACI Convention held in Toronto on April 1st, 2025. The symposium was dedicated to celebrate Prof. Frank J. Vecchio’s extraordinary research contributions and accomplishments in the development of behavioral models and analytical tools for the assessment of concrete structures. The papers cover different aspects related to modeling and performance assessment of concrete structures including developments of the Modified Compression Field Theory, finite element modeling of punching shear in slabs, behavior and modeling of steel fiber reinforced concrete members subjected to torsion, modeling of concrete structures subjected to impact loading, behavior and modeling of slender walls, modeling of concrete frame elements, behavior and modeling of GFRP reinforced members, crack-based assessment of concrete structures, and advancements in modeling deterioration mechanisms and repaired concrete structures. Sincere acknowledgements are extended to all authors, speakers and reviewers as well as to ACI staff for making this symposium a success. Anca-Cristina Ferche, Editor Vahid Sadeghian, Editor

Developed 40 years ago by Frank Vecchio and Michael Collins, the Modified Compression Field Theory (MCFT) and its successor, the Disturbed Stress Field Model (DSFM), have proven to be robust methodologies in modeling the response of concrete structures. Originally developed for newly designed concrete structures, they have been refined over the years to expand their applicability to various engineering problems, including modeling deteriorated and repaired structures. This paper reviews the evolution and application of MCFT in modeling and assessment of deteriorated and repaired concrete structures. The first part focuses on the application of MCFT to advanced field structural assessment, including stochastic analysis procedures that incorporate field data. The second part discusses the evolvement of MCFT to account for two of the most common deterioration mechanisms, reinforcement corrosion and alkali-silica reaction. The last part explores the application of the model to structures repaired with fiber-reinforced polymer composites. It is concluded that the extension of the MCFT formulation has enabled it to reliably predict the behavior of both deteriorated and repaired concrete structures.

Reinforced concrete sections have typically been the most used material for hardened protective construction due to their mass and the ductility provided by the reinforcement. The additional mass of these sections reduces deflections and increases dampening, which reduces vibrations. Even for the occasional occurrence of hardened steel structures, the foundation is comprised of reinforced concrete. Reinforced concrete structures are hardened for a multitude of reasons. The most common include antiterrorism, force protection, equivalent protection for quantity distance arc violations, personnel protection, prevention of prompt propagation, asset protection, and elastic response during repeated intentional detonations. Many of the structures in the United States (US) used by the Department of Defense (DoD), to accommodate a rapid increase in production and storage of explosives were built during World War II (1941-1945). Facilities used for explosives production, maintenance, research and development (R&D), demolition, testing, and training are commonly referred to as Explosives Operating Locations (EOLs). This puts the average age of many of these facilities close to 80 years-old, which is past their originally intended service life. This paper presents a structural health and visual inspection (SHVI) technique developed by the U.S. Army Corps of Engineers (USACE) Facilities Explosives Safety Mandatory Center of Expertise (FES MCX), the University of Oklahoma, and the Engineering Research and Development Center (ERDC) Geotechnical and Structures Laboratory (GSL) for the inspection of reinforced concrete Explosives Operations Location (EOL) facilities and live-fire training facilities [9]. This inspection process has been utilized to inspect over 1500 structures across multiple countries over the last decade and aid DoD installations in planning and budgeting for necessary repairs and future recapitalization priorities. This work does not include application to anti-terrorism or force protection in hardened structures for conventional weapon effects. This process has also been modified for use in live-fire training operations in concrete facilities and coupled with analyses to determine facility adequacy for explosives operations with desired charge weights, based on the given facility’s current structural health rating and its analyzed ability to remain elastic during repeated intentional detonations. The FES MCX partners with ERDC for concrete coring, materials analysis, and testing of samples to determine the estimated remaining service life of concrete structures based on the carbonation front of cored samples determined by the carbonation tests in relationship to the steel reinforcement. Examples of historical application will be given, and details provided on how these methods can lead to improved life-cycle cost for concrete structures and paired with design development criteria for optimal results.

Reinforced concrete sections have typically been the most used material for hardened protective construction due to their mass and the ductility provided by the reinforcement. The additional mass of these sections reduces deflections and increases dampening, which reduces vibrations. Even for the occasional occurrence of hardened steel structures, the foundation is comprised of reinforced concrete. Reinforced concrete structures are hardened for a multitude of reasons. Some of the most common include antiterrorism, force protection, equivalent protection for quantity distance arc violations, personnel protection, prevention of prompt propagation, asset protection, and elastic response during repeated detonations. Many of the structures used in the Department of Defense (DoD), for these purposes, were built in the United States (US) during the World War II era (1941-1945) for a rapid increase in production and storage of explosives. This puts the average age of many of these facilities at close to 80 years-old, which is past their originally intended service life. This paper presents a structural health and visual inspection technique developed by the U.S. Army Corps of Engineers (USACE) Engineering and Support Center Huntsville (CEHNC) Facilities Explosives Safety Mandatory Center of Expertise (FES MCX) and the Engineering Research and Development Center (ERDC) Geotechnical and Structures Laboratory (GSL) for the inspection of reinforced concrete earth covered magazines (ECMs) [9]. This inspection process has been utilized to inspect over 1500 earth covered magazines across multiple countries over the last decade and aid DoD installations in planning and budgeting for concrete repairs and ECM replacements. The CEHNC FES MCX partners with ERDC for concrete coring and testing of samples to determine the estimated remaining service life of concrete structures based on the carbonation front of cored samples determined by the carbonation tests in relationship to the steel reinforcement. Examples of historical application will be given, and details provided on how these methods can lead to improved life-cycle cost and decision making.

While it might seem that hydrodemolition is only appropriate for big projects, it can also be an economical choice for compact applications, such as the renovation of a residential garage floor. The floor had heavy damage that required recasting with new concrete. The floor was diamond ground, so the hydrodemolition method was well-suited to create a rough, consistent bonding surface for the new concrete.