International Concrete Abstracts Portal

Coastal reinforced concrete bridges are critical infrastructures, yet they face significant threats from corrosion due to saline environments and extreme loads like 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 like Performance-Based Earthquake Engineering (PBEE) and Incremental Dynamic Analysis (IDA) to evaluate combined impacts. The findings advocate for engineered cementitious composites (ECC) and advanced sensor systems for improved real-time 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 examines the inaccuracy of the initial strain method that is generally adopted in three-dimensional (3-D) finite element prestressing analysis and discusses the merits of a newly developed method to calculate 3-D prestressing effects. The new method considers friction loss of the tendon force as well as pseudo- centripetal forces, allowing a wide range of functional forms for the prestressed concrete (PC) steel force distribution assumption. This study examined the basic concepts for adopting the functional form of the PC steel force distribution at the prestressing and seating stages, after which the observed and calculated values of pulled-out lengths of PC steel were compared to assure the credibility of the assumed functional form of the PC steel force distribution. A three-span continuous bridge model was used to compare results obtained by the conventional method and the new 3-D method. The equilibrium of a free body was used also to evaluate the accuracy of results by the new method. The importance of the new method being able to calculate a pulled-out PC steel length considering concrete deformation was stressed because this value may be adopted to confirm assumptions of the PC steel force distribution.

Corrosion of carbon-steel reinforcement in marine environments is a significant problem, prompting the use of materials with higher corrosion resistance, such as stainless steel. Despite stainless steel’s superior durability, especially in aggressive environments such as marine structures, it remains vulnerable to localized pitting corrosion, which can be more detrimental than the corrosion observed in carbon steel. The scientific challenge addressed in this study is the lack of extensive research on the degradation of mechanical properties in corroded stainless-steel reinforcing bar. The novelty of this research lies in its focus on ferritic stainless-steel reinforcing bar (SS410L) and the detailed quantification of the relationship between corrosion-induced mass loss and mechanical strength deterioration. An experimental investigation was conducted to assess the impact of different corrosion levels (5, 10, and 20% mass loss) induced using an accelerated impressed-current technique. Tensile tests on both uncorroded and corroded samples provided insights into the reduction of yield load, ultimate load, and elongation. The results revealed that for mass loss percentages of 3.73%, 10.72%, and 23.76%, there was a corresponding reduction in yield load of 6.21%, 29.09%, and 46.56%; ultimate load reductions were 3.43%, 23.91%, and 42.69%; and elongation decreased by 19.45%, 31.28%, and 41.52%, respectively. This study also proposes regression models to predict mechanical property degradation and establishes a relationship between percentage mass loss and crosssectional area loss, highlighting the severe effect of pitting corrosion on mechanical properties based on experimental results.

An experimental investigation was conducted to evaluate the shear-friction capacity of cylindrical pocket connections without reinforcement crossing the interface, which is a common connection detail between precast concrete substructure elements. Current Code expressions for shear-friction capacity include components for cohesion or aggregate interlock and contribution from steel crossing the interface or a clamping force. These expressions were primarily derived and calibrated based on pushoff tests with reinforcement crossing the shear plane, which do not represent the behavior of the shear plane in a cylindrical pocket connection. Thirty-four large-scale specimens were built and tested to investigate the shear friction of the cylindrical pocket connection without reinforcing steel crossing the shear plane. This experimental study showed that current Code expressions provided conservative estimates for this connection. A revised proposed theory is presented that more accurately predicts the shear-friction capacity of this connection without interface steel.

This paper presents the behavior of unreinforced cylindrical concrete elements confined with a hybrid system, consisting of an ultra-high-performance concrete (UHPC) jacket and basalt fiber-reinforced polymer (BFRP) grids. For exploring the feasibility of the proposed strengthening scheme, a series of tests are conducted to evaluate material properties and to obtain results related to interfacial bond, load-bearing capacity, axial responses, and failure modes. To understand the function of the individual components, a total of 57 cylinders are loaded under augmented confining conditions, including plain cores with ordinary concrete (CONT), plain cores with UHPC jackets (Type A), and plain cores with UHPC jackets plus BFRP grids (Type B). By preloading the cores at up to 60% of the control capacity (60%fc′) before applying the confinement system, the repercussions of inherent damage that can take place in vertical members on site are simulated. The compressive strength of UHPC rapidly develops within 7 days, whereas its splitting strength noticeably ascends after 14 days. The adhesion between the ordinary concrete and UHPC increases over time. While the Type B specimens outperform their Type A counterparts in terms of axial capacity by more than 18%, reliance on the BFRP grids is reduced with the growth of UHPC’s strength and adhesion because of the interaction between the hardened UHPC and the core concrete. The adverse effects of the preloading are noteworthy for both types, especially when exceeding a level of 30%fc′. The BFRP grid-wrapping alleviates the occurrence of a catastrophic collapse in the jacketed cylinders, resulting from a combination of the axial distress and lateral expansion of the core. Analytical models explain the load-carrying mechanism of the strengthened concrete, including confinement pressure and BFRP stress. Through parametric investigations, the significance of the constituents is clarified, and design recommendations are suggested.