International Concrete Abstracts Portal

Corrosion—one of the major threats to the integrity of concrete structures—can consequently affect structure serviceability and ultimate limit state, possibly resulting in failure. Glass fiber-reinforced polymer (GFRP) can be used as an innovative alternative for conventional steel reinforcement in concrete structures, effectively addressing corrosion issues. In addition to its corrosion resistance and high strength-to-weight ratio, GFRP is commonly selected for non-prestressed bars and stirrups due to its cost advantage over other FRP materials. The study endeavored to provide a comprehensive overview of the shear resistance in GFRP-RC beams with short shear spans. The manuscript aims to synthesize and analyze shear test data based on published studies on GFRP-RC beams with a short shear span (a/d = 1.5 to 2.5). A comprehensive literature review was conducted to compile a database comprising 64 short GFRP-RC beams to evaluate the efficiency of using the strut-and-tie model (STM) for predicting the shear resistance of GFRP-RC beams. The findings reveal that the ACI 318 (2019) STM yielded the most accurate predictions of the shear resistance of GFRP-RC beams with shear span-to-depth ratios of 1.5 to 2.5, since the current ACI 440.11 and ACI 440.1R design codes and guidelines do not include shear equations using the strut-and-tie model for predicting the shear resistance of GFRP-RC beams. Based on the findings of this study, the results could contribute to establishing shear equations in the upcoming revision of the ACI 440.11 and ACI 440.1R design codes and guidelines, specifically tailored for designing short GFRP-RC beams using the strut-and-tie model. The study also provides sufficient data to apply the strut-and-tie model in the design of GFRP-RC beams.

This research establishes a systematic methodology for selectinga migratory corrosion inhibitor (M-CoI) as a repair strategy forreinforced concrete (RC) structures exposed to aggressive environments. Conducted in two phases, Phase 1 involves corrosion testing in pore solutions to evaluate inhibitor efficacy, while Phase 2 examines the percolation ability of M-CoIs in different concrete systems and performance of M-CoI in RC with corroded reinforcing bars. The findings reveal that the efficiency of the compounds as repair measures is significantly lower than their preventive performance, primarily due to the presence of corrosion products onthe steel surface. Additionally, the effectiveness of the M-CoIs isinfluenced by their concentration and form at the reinforcing barlevel; specifically, 4-Aminobenzoic acid (ABA) achieved maximumconcentration in its purest form, whereas Salicylaldehyde (SA) and2-Aminopyridine (AP) reached the reinforcing bar in lower concentrations. Importantly, the study highlights that compounds effective in pore solution may not perform well in concrete, underscoring the necessity of considering the intended application—preventive or repair—when selecting inhibitors. Thus, a comprehensive approach involving both pore solution testing and migration ability assessments is essential for optimal corrosion protection in reinforced concrete.

Coastal reinforced concrete (RC) bridges are critical infrastructures, yet they face significant threats from corrosion due to saline environments and extreme loads such as wave-induced forces and seismic events. This state-of-the-art review examines the resilience of corrosion-damaged RC bridges under such conditions. It compiles advanced methodologies and technological innovations to assess and enhance durability and safety. Key highlights include synthesizing loss estimation models with advanced reliability methods for a robust resilience assessment framework. Analyzing catastrophic bridge failures and environmental deterioration, the review underscores the urgent need for innovative materials and protective technologies. It emphasizes advanced analytical models including performance-based earthquake engineering (PBEE) and incremental dynamic analysis (IDA) to evaluate combined impacts. The findings advocate for engineered cementitious composites (ECCs) and advanced sensor systems for improved realtime monitoring and resilience. Future research should focus on developing comprehensive resilience models accounting for corrosion, seismic, and wave-induced loads to enhance infrastructure safety and sustainability.

This paper proposes a series of empirical modifications to an existing three-step analytical model used to derive the cyclic shear capacity of circular reinforced concrete (RC) columns considering corrosive conditions. The results of 16 shear-critical RC columns, artificially corroded to various degrees and tested under quasistatic reversed cyclic loading, are used for model verification. The final model is proposed in a piecewise damage-state format relative to the measured damage of the steel reinforcement. New empirical decay coefficients are derived to determine the degraded material properties based on an extensive database of over 1380 corroded tensile tests. An additional database of 44 corroded RC circular piers is collected to assist in the modification of ductility-based parameters. Compared to the shear-critical test specimens, the model results indicate that the peak shear capacity can be predicted well across a range of deterioration severities (0 to 58.5% average transverse mass loss), with a mean predictive ratio of ±8.60%. As damage increases, the distribution of the corrosion relative to the location of the shear plane becomes a critical performance consideration, increasing predictive variance.

Noncorrosive fiber-reinforced polymer (FRP) reinforcement presents an attractive alternative to conventional steel reinforcement, which is prone to corrosion, especially in harsh environments exposed to deicing salt or seawater. However, FRP reinforcing bars’ lower axial stiffness leads to greater crack widths when FRP reinforcing bars elongate, resulting in significantly lower flexural stiffness for FRP bar-reinforced concrete members. The deeper cracks and larger crack widths also reduce the depth of the compression zone. Consequently, both the aggregate interlock and the compression zone for shear resistance are significantly reduced. Additionally, due to their limited tensile ductility, FRP reinforcing bars can rupture before the concrete crushes, potentially resulting in sudden and catastrophic member failure. Therefore, ACI Committee 440 states that through a compression-controlled design, FRP reinforced concrete members can be intentionally designed to fail by allowing the concrete to crush before the FRP reinforcing bars rupture. However, this design approach does not yield an equivalent ductile behavior when compared to steel-reinforced concrete members, resulting in a lower strength reduction, ϕ, value of 0.65. In this regard, using FRP-reinforced ultra-high-performance concrete (UHPC) members offer a novel solution, providing high strength, stiffness, ductility, and corrosion-resistant characteristics. UHPC has a very low water-cementitious materials ratio (0.18 to 0.25), which results in dense particle packing. This very dense microstructure and low water ratio not only improves compressive strength but delays liquid ingress. UHPC can be tailored to achieve exceptional compressive ductility, with a maximum usable compressive strain greater than 0.015. Unlike conventional designs where ductility is provided by steel reinforcing bars, UHPC can be used to achieve the required ductility for a flexural member, allowing FRP reinforcing bars to be designed to stay elastic. The high member ductility also justifies the use of a higher strength reduction factor, ϕ, of 0.9. This research, validated through large-scale experiments, explores this design concept by leveraging UHPC’s high compressive ductility, cracking resistance, and shear strength, along with a high quantity of noncorrosive FRP reinforcing bars. The increased amount of longitudinal reinforcement helps maintain the flexural stiffness (controlling deflection under service loads), bond strength, and shear strength of the members. Furthermore, the damage resistant capability of UHPC and the elasticity of FRP reinforcing bars provide a structural member with a restoring force, leading to reduced residual deflection and enhanced resilience.