The special sessions will focus on advances in the serviceability of concrete bridges and structures. Of interest are presentations concerning a wide variety of technical aspects from laboratory experiments to field applications. Specific subjects include the prediction of deflections in reinforced and prestressed concrete members, cracking problems and mitigation methodologies, state-of-the-art evaluation techniques, strategies to achieve the concept of serviceability-based design and construction, and practical approaches that can assist engineering professionals in retaining serviceability requirements.
Serviceability of Tall Concrete Buildings Subject to Wind
Presented By: Thomas Kang
Affiliation: Seoul National University
Description: Wind is a major consideration in the design and construction of high-rise buildings. This presentation focuses on the serviceability of multi-story buildings subjected to wind.
The Discrepancy in Prescriptive Shear Reinforcement Requirements Between Large-Scale Slender and Non-Slender Beams
Presented By: Robin Tuchscherer
Affiliation: Northern Arizona University
Description: Prescriptive shear reinforcement requirements in ACI 318 (2019) require slender beams to contain a minimum area of web reinforcement equal to 0.08% of the cross-section, while non-slender beams require 0.25%, or roughly three times as much. This discrepancy is a source of frustration among bridge engineers as it can result in a substantial increase in stirrups for large beams. This paper illustrates the discrepancy through a case study examination of a pier cap. Given the discrepancy, the objective of the study summarized in this paper is to conduct a database analysis and evaluate the effects of vertical and horizontal web reinforcement on the strength and serviceability performance of experimental test specimens. Based on the findings, the minimum web reinforcement needed to ensure a beam’s capacity is consistent with code requirements for slender beams but not deep beams, and the minimum web reinforcement needed to control crack widths is consistent with code requirements for non-slender but not slender beams.
Fragility Curve for Service Life Prediction of Concrete Structures
Presented By: Jae Hong Kim
Affiliation: KAIST
Description: Service life of a concrete structure is usually predicted by evaluating its resistance to chloride attack related to rebar corrosion. The time for chloride ions arriving reinforcing bars is an indicator for predicting the service life. The diffusivity of chloride ions through cover concrete is a key factor for the calculation of service life span, but it inherently has a large variation compared to the strength and other mechanical properties. Considering the diffusivity as a random variable allows us to analyze the inherent variation of the diffusivity. A large number of concrete samples are subjected to the diffusivity measurement by NT BUILD 492. The statistical distribution of the diffusivity is then developed modeling it as a probabilistic variable. Applying Fick’s 2nd law with the diffusivity results in calculating the probabilistic service life of a concrete structure. This study finally proposes chloride-attack fragility by evaluating the probability of failure at a given confidence level.
Serviceability of Concrete Structures for Explosives Storage
Presented By: Christopher Moore
Affiliation: US Army Corps of Engineers
Description: This paper presents a structural health and visual inspection technique developed by the U.S. Army Corps of Engineers (USACE) 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). This inspection process has been utilized to inspect over 1000 earth covered magazines across multiple countries over the last decade and aid Department of Defense (DoD) installations in planning and budgeting for concrete repairs and ECM replacements. The 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 lifecycle cost for concrete structures and paired with design development criteria for optimal results.
Development of Structural Integrity Assessment Technologies for a Concrete Containment Structure under Ultimate Pressure Condition
Presented By: Min Kyu Kim
Affiliation: Korea Atomic Energy Research Institute
Description: The containment building of a nuclear power plant is the last barrier of defense to maintain safety in the event of a severe accident, and the integrity of the containment building is the last line of defense against the release of radioactive material. Among the worst nuclear accidents in human history, the Tree Mile Island nuclear power plant accident in 1979, the Chernobyl nuclear power plant accident in the Soviet Union in 1986, and the Fukushima nuclear power plant accident caused by the Great East Japan Earthquake in 2011, the TMI nuclear power plant accident was able to prevent the leakage of radioactive substances even though a severe accident occurred because the containment building remained sound. This proves the importance of containment buildings. Nuclear power plant containment buildings are most commonly constructed of prestressed concrete, but there are also some constructed of steel. In the case of PS concrete containment building, in order to prepare for the increase in internal pressure in the event of a severe accident, compression force is applied using a tendon in advance to secure sufficient safety, but due to the characteristics of concrete, cracks may occur, and these cracks may become a pathway for external leakage of radioactive materials in the event of a severe accident. In addition, a number of corroded cavities and degradation of liner plates have been found in recent Korean nuclear power plants. Therefore, a study to evaluate the safety of PS concrete containment buildings began in 2022, started by the Korea Atomic Energy Research Institute, and will be conducted for eight years until 2029. Although a variety of researches are being conducted to evaluate the integrity of concrete containment buildings, the purpose of the research can be categorized into two main areas. The first is to derive the probability of failure of concrete containment buildings due to an increase in internal pressure in the event of a severe accident.
State-of-the-Art GPR for Bridge Inspection: Performance and Future Directions of the Conquest 100
Presented By: Priyam Chowdhury
Affiliation: Rowan University
Description: Ground penetrating radar (GPR) offers a powerful non-destructive testing (NDT) method for infrastructure evaluation. Various GPR scanner models are sold commercially, and choosing the optimal one for a given application can be challenging due to a lack of comprehensive knowledge of various GPR technologies and their suitability for different infrastructure inspection tasks. That’s why, to help the experts, there is a need to review the most recent states of practice and research on applying GPR technologies. This presentation aims to address this gap by thoroughly analyzing commonly occurring defects and features inside bridge decks and girders using one of the most recent GPR sensors.