International Concrete Abstracts Portal

Accurate prediction of bond strength between steel reinforcement and concrete is essential for assessing structural safety and durability, particularly under reinforcement corrosion, where existing design codes such as ACI 408R-03 lack explicit modifiers. This study presents a physics-guided Bayesian framework that integrates dimensional analysis, probabilistic calibration, and uncertainty quantification to model bond strength while explicitly accounting for experimentally observed factors, including corrosion. Starting from a dimensionless power-law derived via Buckingham’s π-theorem, bond strength is expressed with globally interpretable exponents for embedment-to-diameter and cover-to-diameter ratios, while the scaling coefficient is adaptively modeled as a nonlinear function of experimental variables—including corrosion level, stirrup ratio, rebar type, and test method—through Random Fourier Features. Bayesian inference with Markov Chain Monte Carlo enables calibrated predictions with explicit decomposition of aleatoric and epistemic uncertainty, providing transparent insights into variability sources. Model performance and uncertainty behavior are examined through cross-validation and external validation. Beyond predictive performance, posterior analysis yields a concise, physics-consistent bond strength equation that explicitly incorporates corrosion effects and quantifies uncertainty, providing a practical and interpretable tool for reliability-based assessment of reinforced concrete structures.

Although grouted splice-sleeve connectors (GSSCs) are notably used in precast concrete structures, steel sleeves are heavy and have corrosion issues. The bond characteristics of GSSCs using cylindrical and tapered fiber-reinforced polymer (FRP) sleeves—lighter alternatives—were investigated in this study. A series of pullout tests for 144 specimens were conducted to evaluate the effects of FRP type, number of layers, shape, and length on the bond characteristics of GSSCs. The test results showed that for FRP GSSCs, tapered FRP sleeves effectively developed confinement compared with cylindrical FRP sleeves, leading to better bond strength and shorter development length. A design equation was proposed for estimating the tensile strength of FRP-based GSSCs, which predicted well the test results. The tapered FRP sleeves reduced the development length compared with cylindrical FRP sleeves, implying greater FRP GSSC efficiency in precast concrete structures, which provides engineers with valuable insights for efficient FRP splice-sleeve design in precast concrete structures.

An experimental investigation was conducted to examine the behavior of reinforced concrete (RC) beams subjected to service loads coupled with corrosion of the main flexural reinforcement. A total of nine beams with dimensions of 145 x 250 x 1800 mm (5.71 x 9.84 x 70.87 in.) were constructed. The main test variables were corrosion current density and level of service loading. The beams were loaded under a four-point bending test to either 60, 40, or 0% of the beam ultimate capacity. Applied loads and reinforcement corrosion were sustained until the failure of beams. Test results indicate that the failure of corroded RC beams becomes brittle, resulting in premature rupture of corroded steel bars. This behavior is attributed to the development of localized corrosion at sections with flexural cracks in beams. Furthermore, it was found that beams subjected to higher levels of service loading experienced further reductions in ultimate load capacity and ductility.

Reinforced concrete members derive flexural strength from reinforcing steel, which acts together with concrete to reach the required capacity. Design standards stipulate mandatory norms that must be complied with during the design process. Noncompliance with these provisions can increase the risk of corrosion, compromising the safety and integrity of the structure. Concrete provides protection to the reinforcing steel against corrosion, but it can also become a contributing factor when its microstructure is poor due to noncompliance with these norms. Assessing the residual flexural capacity is essential for making informed decisions regarding repair or demolition. The proposed model in this paper enables computation of the reduction in flexural strength based either on gravimetric mass-loss percentage or on measured corrosion current density. A design chart is also proposed to facilitate practical application, enabling engineers to assess residual capacity and decide on repair or demolition.

Drilling support fluid is used to stabilize deep excavations during the construction of cast-in-place concrete foundations like drilled shafts. During concreting operations, flowable concrete, tremie-placed or pumped to the bottom of the excavation, displaces the lower-density support fluid. Reinforcement cage congestion from tight rebar spacing requires concrete to build sufficient pressure head inside the reinforcement cage before radially filling the annular cover region. Even under ideal conditions, the support fluid-concrete interface produced during radial flow has been proven to impact side shear capacity, corrosion resistance, concrete strength, and rebar bond strength. These effects largely go unnoticed. This paper compiles the findings of 13 studies conducted to highlight the impact of support fluid performance on drilled shaft construction while providing recommendations vital to the evolution of concrete placement practices in deep excavations.