International Concrete Abstracts Portal

This study presents the design, construction, and shaking table testing of a two-column bridge bent developed for accelerated bridge construction with low-seismic damage objectives. The system incorporates precast post-tensioned columns connected to precast foundation and bent caps, with each column consisting of reinforced concrete cast inside a cylindrical steel shell that serves as formwork, confinement, and shear reinforcement. The steel shell is detailed to promote a rocking interface that concentrates seismic deformation demands at the column ends. Precast foundation and cap elements contain corrugated-metal-duct lined sockets, allowing on-site grouting to form the joints. A 35%-scale bent was constructed and subjected to combined horizontal and vertical ground motion inputs on a shaking table. Testing confirmed that seismic rotations concentrated at the column ends as intended, the bent exhibited excellent recentering capability, and observed damage was minimal, thus, validating the design objectives.

It can be demonstrated that performance-based seismic design of post-installed anchors in accordance with ACI 318 is not possible using the anchor qualification information provided by ACI 355. The current state-of-the-art anchor qualification does not provide capacities that reflect actual earthquake responses in seismic design scenarios. This paper provides a comprehensive analysis and highlights the gaps in the current approach. A performance-based framework is proposed for the basis of future developments in seismic design and qualification of post-installed anchors. It is demonstrated that the approach is fully transparent and provides the possibility to identify key driving parameters that need further experimental investigation. The approach acknowledges that performance-based seismic design of post-installed anchors needs the understanding of the seismic damage of the concrete-anchor system. Currently, no design tools are available to predict this damage. The proposed framework adopts the theory of the accumulated damage potential (ADP) as the damage parameter. It is demonstrated that the selected damage parameter is simple but meaningful enough to represent the seismic damage of the concrete-anchor system at the design level. Possibilities for future development of the approach are explored, and directions for the next steps are suggested. It is highlighted that definition of a framework for realistic seismic performance objectives of post-installed anchors is needed for the development of design tools in the future. The proposed framework has great practical significance and may help fill a gap in the seismic design of post-installed anchors. Promoting a transparent framework that is driven by the needs of performance-based seismic design may help develop a feasible qualification system and replace the currently used pass-or-fail assessment approach, which is not suitable to provide anchor capacities for performance-based seismic design.

This study presents a comprehensive review of eco-friendly materials and advanced repair techniques for rehabilitating reinforced concrete (RC) structures, emphasizing their role in promoting sustainability and enhancing performance. By evaluating 55 research programs conducted between 2001 and 2024, the study focuses on emerging materials such as geopolymers, natural fibers, and fiber-reinforced composites, highlighting their mechanical properties, environmental benefits, and potential for integration into traditional RC systems. The review is thematically organized into four areas: 1) sustainability and environmental impacts; 2) material innovation and properties; 3) repair techniques and efficiency; and 4) structural performance. Key findings reveal that these materials not only reduce the carbon footprint of construction but also significantly improve structural durability, corrosion resistance, and long-term performance under varying environmental conditions. Specifically, geopolymer concretes exhibit low CO2 emissions and superior bond strength, bamboo and flax fibers offer strong tensile capacity with renewable sourcing, and microbially induced carbonate precipitation (MICP) techniques deliver self-healing functionality that reduces dependency on chemical-based crack sealants. Additionally, the use of recycled and bio-based materials further contributes to cost-efficiency and environmental resilience, fostering circular economy principles. By synthesizing findings across these domains, this study provides practical insights into how eco-friendly materials can simultaneously address environmental, structural, and economic challenges in RC repair. The study underscores the importance of adopting innovative repair methods that incorporate these sustainable materials to address modern civil engineering challenges, balancing infrastructure longevity, sustainability, and reduced environmental impact.

This paper presents an experimental study on the residual bond of glass fiber-reinforced polymer (GFRP) reinforcing bars embedded in ultra-high-performance concrete (UHPC) subjected to elevated temperatures, including a comparison with ordinary concrete. Based on the range of thermal loading from 25 to 300°C (77 to 572°F), material and pushout tests were conducted to examine the temperature-dependent properties of the constituents and behavior of the interface. Also performed were chemical and radiometric analyses. The average specific heat and thermal conductivity of UHPC are 12.1% and 6.1% higher than those of ordinary concrete, respectively. The temperature-induced reduction of density in these mixtures ranges between 5.4 and 6.2% at 300°C (572°F). Thermal damage to GFRP, in the context of microcracking, was observed after exposure to 150°C (302°F). Fourier transform infrared spectroscopy (FTIR) reveals prominent wavenumbers at 668 and 2360 cm–1 (263 and 929 in.–1), related to the bond between the fibers and resin in the reinforcing bars, while spectroradiometry characterizes the thermal degradation of GFRP through diminished reflectivity in conjunction with the peak wavelength positions of 584 nm (2299 × 10–8 in.) and 1871 nm (7366 × 10–8 in.). The linearly ascending bond-slip response of the interface alters after reaching the maximum shear stresses, leading to gradual and abrupt declines for ordinary concrete and UHPC, respectively. The failure mode of the ordinary concrete interface is temperature-sensitive; however, spalling in the bonded region is consistently noticed in the UHPC interface. The fracture energy of the interface with UHPC exceeds that of the interface with the ordinary concrete beyond 150°C (302°F). Design recommendations are provided for estimating reductions in the residual bond of the GFRP system exposed to elevated temperatures.

The paper presents a comparative study on the seismic behavior of circular columns reinforced with glass fiber-reinforced polymer (GFRP) and steel. The study specifically investigates the influence of replacing steel bars with GFRP bars on columns’ seismic response. All the studies summarized in this paper were conducted at the University of Toronto, Toronto, ON, Canada. Results from the tests of 24 columns (all having 356 mm [14 in.] diameter and tested in a similar manner) from three different studies are closely analyzed to compare their responses. Based on the experimental results, it is found that replacing steel spirals with GFRP spirals did not result in substantial variation in the seismic performance of columns. Both types demonstrated similar ductility parameters and drift ratios when similar amounts of spirals were used at comparable pitches. Likewise, columns with steel longitudinal reinforcement and GFRP longitudinal reinforcement achieved similar deformation capacities but with lower strength and stiffness.