International Concrete Abstracts Portal

Serviceability is considered a critical factor in the management of concrete bridges and structures. Typical components for evaluating the serviceability limit state include cracking, deflection, and vibration. Additionally, to ensure the adequate performance of load-bearing members, proper evaluation methodologies should be adopted. Although numerous research projects have been undertaken to examine the serviceability and performance assessment of concrete bridges and structures, significant endeavors are still required to address unexplored challenges. Of interest are the development of simplified prediction and appraisal approaches; novel techniques for quantifying stress levels; serviceability criteria under unusual distress; and the characterization of structural responses when exposed to blast, wind, and seismic loadings. This Special Publication contains 11 papers selected from technical sessions held in the ACI Fall Convention in November 2024. The Editors wish to thank all contributing authors and anonymous reviewers for their rigorous efforts. The Editors also gratefully acknowledge Ms. Barbara Coleman at ACI for her knowledgeable guidance. Yail J. Kim, University of Colorado Denver, Editor Hyeon-Jong Hwang, Konkuk University, Editor

Modular construction has been attracting attention worldwide as a promising solution to reduce construction time and labor demand. In this study, a new inter-module composite floor system that connects the upper module floor beams and lower module ceiling beams was experimentally and analytically investigated with an emphasis on vibration performance under service loading. First, the upper module floor of 2 m [6.56 ft] wide and 6 m [19.7 ft] long was fabricated as a composite system consisting of precast concrete (PC) panels, steel beams and ultra high-performance concrete (UHPC) connectors. Structural integrity between PC panels, steel beams and UHPC connectors were secured using grouting and topping mortar. Then, the lower module ceiling beams were connected to the upper module floor beams by fully tensioned high-tension bolts (i.e., slip-critical connection) to complete the inter-module composite floor. The vibration frequencies, damping ratio, and acceleration responses of the inter-module composite floors were measured from laboratory tests such as impact hammer, heel drop and walking tests, considering the number and location of the connecting bolts as the test parameter. The vibration characteristics of the inter-module composite floors were investigated further through finite element analysis. The measured and predicted vibration performances were compared with the acceptance criteria in AISC Design Guide 11 and ISO 10137.

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.

Optimum thickness of a concrete flat plate is the best or the most favourable for an objective. The most common objective is often miuimum cost; however, it can also be noise insulation, least vibration or plane soffit, with or without beams or drop panels. The minimum cost is often achieved by the smallest thickness that avoid excessive deflection in service. With small thickness, reinforcement is commonly needed for safety against shear failure. Part I: Serviceability, presents a procedure to predict long-term deflection of floors and bridge decks considering the effects of cracking, creep and shrinkage of concrete and relaxation of prestressing reinforcement. The system consists of a solid slab with or without drop panels and/or beams. For analysis, the system is idealized as grid of rigidly connected short beam elements. Strain distributions at end sections are determined, assuming linear elasticity and that plane cross sections remain plane. The analysis is based on compatibility and equilibrium principles, combined with time-dependent parameters for concrete and prestressed reinforcement. The displacements – translations and rotations – are determined from strain parameters by virtual work. Part II is concerned with design of slabs for shear strength.