More Like this

1. Probabilistic prediction model for RC bond failure mode

   https://doi.org/10.1016/j.engstruct.2021.111944  

   Soraghi, Ahmad; Huang, Qindan (January 2021, Engineering structures)

   null (Ed.)

   Adequate rebar-concrete bonding is crucial to ensure the reliable performance of reinforced concrete (RC) structures. Many factors such as the concrete properties, concrete cover depth, transverse reinforcement, and the presence of corrosion will affect the bond behavior, and consequently, the structural performance. While many prior studies have focused on the influence of the aforementioned factors on the bond strength, the impact of these factors on the bond failure mode has not been thoroughly investigated. A probabilistic bond failure mode prediction model that considers various influencing factors including loading type and corrosion is developed in this study. This study uses the bond testing results of 132 beam-end specimens subjected to monotonic and cyclic loading and adopts classification methods to develop the prediction model, which is then used to evaluate the impact of bond behavior on the reliability of a RC beam with a lap splice. 

   more » « less
2. Time Dependent Strength and Stiffness of Shear Controlled Reinforced Concrete Beams under High Sustained Stresses

   https://doi.org/10.1061/9780784482896.005  

   Clark, Russell; Shubaili, Mohammed; Elawadi, Ali; Orton, Sarah; Tian, Ying (April 2020, 2020 Structures Congress)

   Design and construction errors and material deterioration can lead to concrete elements being subjected to high levels of sustained stress well exceeding typical service levels. These high levels of sustained stress have led to structural collapses in the United States and around the world. However, the performance of shear-controlled concrete elements (beams and slab-column connections) under high sustained stress is not well understood. Under high sustained compressive stress (greater than 0.75fc’) concrete will suffer tertiary creep characterized by accelerated permanent strain, leading eventually to a failure. The bond of the reinforcing bars to the concrete is also affected leading to slip. This research presents the results of experimental tests on shear-controlled RC beams that were loaded to 81, 86, and 92 percent of their short-term capacity and observed for about four weeks. Deflection and strain measurements were recorded for each specimen throughout the sustained load test. Under high sustained stress the specimens showed continued deflection with time, with most of the deflection occurring shortly after the application of load. The failure of the specimens exhibited more flexural response than that of the control specimen. The test results show that high levels of sustained stress (up to 92% of their short-term capacity) can be sustained for a prolonged time; however, the deflections and cracking are increased and the ultimate failure mode may be changed. This information will help engineers identify elements nearing failure under high levels of sustained stress. 

   more » « less
3. Artificial intelligence-enhanced seismic response prediction of reinforced concrete frames

   https://doi.org/10.1016/j.aei.2022.101568  

   Luo, Huan; Paal, Stephanie German (April 2022, Advanced Engineering Informatics)

   Existing physics-based modeling approaches do not have a good compromise between performance and computational efficiency in predicting the seismic response of reinforced concrete (RC) frames, where high-fidelity models (e.g., fiber-based modeling method) have reasonable predictive performance but are computationally demanding, while more simplified models (e.g., shear building model) are the opposite. This paper proposes a novel artificial intelligence (AI)-enhanced computational method for seismic response prediction of RC frames which can remedy these problems. The proposed AI-enhanced method incorporates an AI technique with a shear building model, where the AI technique can directly utilize the real-world experimental data of RC columns to determine the lateral stiffness of each column in the target RC frame while the structural stiffness matrix is efficiently formulated via the shear building model. Therefore, this scheme can enhance prediction accuracy due to the use of real-world data while maintaining high computational efficiency due to the incorporation of the shear building model. Two data-driven seismic response solvers are developed to implement the proposed approach based on a database including 272 RC column specimens. Numerical results demonstrate that compared to the experimental data, the proposed method outperforms the fiber-based modeling approach in both prediction capability and computational efficiency and is a promising tool for accurate and efficient seismic response prediction of structural systems. 

   more » « less
4. Hybrid Reinforced Concrete Cross-Section Using Fiber-Reinforced Polymer and Steel Bars

   https://doi.org/10.1186/s40069-024-00753-1  

   Hussain, Zahid; Tuozzo, Federico; Magliulo, Gennaro; Nanni, Antonio (April 2025, International Journal of Concrete Structures and Materials)

   Abstract Fiber-reinforced polymer (FRP) bars offer a promising alternative to conventional steel reinforcement in reinforced concrete (RC) structures, primarily due to their corrosion resistance. However, their intrinsic linear elastic behavior may limit their applications to non-seismic zones or regions with limited seismic activity. To extend their applications in seismic zones such as Seismic Design Category D, a novel approach involving a hybrid-RC (HRC) cross-section is proposed. This approach entails placing FRP bars on the cross-section exterior for corrosion resistance, while steel bars on the inner side of the cross-section to ensure ductility and energy dissipation. This paper presents a methodology for designing HRC cross-sections and evaluates their ductility and energy dissipation capabilities. The discussion encompasses various design aspects of an HRC section including strength reduction factor, minimum reinforcement ratio, reinforcement strain, concrete shear strength, and the impact of confinement on ductility and energy dissipation. Additionally, an illustrative example of a HRC section demonstrates the practicality of the proposed design methodology in practical applications. 

   more » « less
5. Time-Dependent Behavior of Reinforced Concrete Beams under High Sustained Loads

   https://doi.org/10.3390/app12084015  

   Shubaili, Mohammed; Elawadi, Ali; Orton, Sarah; Tian, Ying (April 2022, Applied Sciences)

   High levels of sustained load can lead to time-dependent failure of reinforced concrete (RC) members. This in turn may lead to collapse of all or part of a building. Design errors, construction errors, and material deterioration may lead to concrete elements being subjected to high levels of sustained loads well exceeding typical service loads. Plain concrete can experience compressive failure when subjected to a high sustained stress (over 75% of its short-term strength). However, there is a lack of knowledge about the time-dependent strength and stiffness characteristics of RC members under high sustained loads. This paper presents the results of experimental testing of simply supported shear-controlled RC beams under high sustained loads. Two series of beams, consisting of 4 and 5 beams, were tested at concrete ages of 67 to 543 days to represent in-service concrete structures. The applied sustained loads ranged from 82% to 98% of the short-term capacity and lasted for 24 to 52 days. Test results indicated that high sustained load may eventually lead to failure (collapse); however, the level of load needs to be very close (~98%) to the short-term capacity. Under sustained load, all specimens experienced increased deflection with over half of the deflection increase occurring in the first 24 h. The sustained load increased the deflection at shear failure by 190% on average. The increase in the beam deflection may allow for load redistribution in redundant structural systems. A sharp increase in deflection due to tertiary creep occurred in a short time (~2 min) before failure, indicating little warning of the impending failure. 

   more » « less