Rehabilitation and Strengthening Techniques for Reinforced Concrete

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Buildings buildings	3.1	4.4	2011	15.1 Days	CHF 2600	Submit
CivilEng civileng	2.0	4.0	2020	21.7 Days	CHF 1400	Submit
Construction Materials constrmater	-	3.1	2021	20.9 Days	CHF 1200	Submit
Crystals crystals	2.4	5.0	2011	12.7 Days	CHF 2100	Submit
Infrastructures infrastructures	2.9	6.0	2016	18.3 Days	CHF 1800	Submit
Materials materials	3.2	6.4	2008	15.5 Days	CHF 2600	Submit
Solids solids	2.4	4.5	2020	18.3 Days	CHF 1200	Submit

17 pages, 8604 KB

Open AccessArticle

Structural Behavior of Pre-Loaded Fire-Damaged RC Columns Rehabilitated with UHPC

by Mohanad Wisam Mousa, Sarmad Shafeeq Abdulqader and Ahlam Sader Mohammed

Infrastructures 2026, 11(3), 92; https://doi.org/10.3390/infrastructures11030092 - 11 Mar 2026

Cited by 1 | Viewed by 382

This study presents an experimental investigation into the rehabilitation of fire-damaged reinforced concrete (RC) columns using Ultra-High-Performance Concrete (UHPC) under an eccentric load of (e = 45 mm). The experimental program comprised nine small-scale RC column specimens, which were divided into two groups [...] Read more.

This study presents an experimental investigation into the rehabilitation of fire-damaged reinforced concrete (RC) columns using Ultra-High-Performance Concrete (UHPC) under an eccentric load of (e = 45 mm). The experimental program comprised nine small-scale RC column specimens, which were divided into two groups based on exposure temperatures of 500 °C and 700 °C, applied using a specially designed furnace. A control column that was not exposed to fire was also tested for comparison. The study included two fire exposure durations: 60 and 120 min. During the heating phase, the columns were subjected to a pre-applied axial load equal to 50% of their ultimate capacity (Pu). After sustaining fire-induced damage, the columns were rehabilitated using UHPC jacketing. The experimental results revealed a reduction in the ultimate load-carrying capacity of the RC columns with increasing fire temperature and exposure duration. Specifically, the load capacity decreased by 22.68% and 33.89% when exposed to 500 °C for 60 and 120 min, respectively, and by 42.02% and 49.02% when exposed to 700 °C for 60 and 120 min, respectively, compared with the control column. However, strengthening the fire-damaged columns with UHPC significantly enhanced their structural performance, resulting in an increase in ultimate load capacity ranging from 81.88% to 157.14% compared with their corresponding fire-damaged unstrengthened specimens. Based on the experimental findings, the load lateral displacement response at mid-height, load–axial deformation curves, failure modes, ductility, and stiffness characteristics of the columns were analysed. The study concludes that the use of UHPC in rehabilitating fire-exposed columns substantially improves most of these structural properties. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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20 pages, 4202 KB

Open AccessArticle

Analytical and Experimental Assessment of RC Beams Strengthened Using Galvanised Steel Sheets

by Gilmer Challco, Dennis Apaza, Daniel Rodriguez, Erika Rodriguez, Blanca Bautista and Daniel Quiun

Infrastructures 2026, 11(3), 80; https://doi.org/10.3390/infrastructures11030080 - 3 Mar 2026

Viewed by 504

Abstract

While steel sheets are an effective strengthening technique for existing structures, experimental evidence on galvanised steel sheets is limited, necessitating their evaluation as a durable and cost-effective solution for the flexural strengthening of reinforced concrete (RC) beams. This study analyses the influence of [...] Read more.

While steel sheets are an effective strengthening technique for existing structures, experimental evidence on galvanised steel sheets is limited, necessitating their evaluation as a durable and cost-effective solution for the flexural strengthening of reinforced concrete (RC) beams. This study analyses the influence of external reinforcement using galvanised steel sheets applied to RC beams. The structural behaviour of the specimens was assessed through flexural tests, with monotonic loading applied at one-third and two-thirds of the effective span, in accordance with ASTM C78 guidelines. In addition, an analytical model was formulated to capture the non-linear behaviour of concrete, reinforcing steel, and galvanised steel sheets. The results indicate that beams strengthened with external reinforcement exhibit an increase in load-bearing capacity of up to 69% in the elastic range, together with significant improvements in ductility of up to 22%. Moreover, the use of vertical U-wrap sheets and anchor bolts enhances the bond between the sheets and the concrete, thereby reducing the risk of premature debonding. Overall, the findings confirm that the use of galvanised steel sheets is an effective and practical strengthening technique for improving the flexural performance of RC beams. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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26 pages, 5896 KB

Open AccessArticle

Experimental Study on Axially Loaded Reinforced Concrete Columns Strengthened with Steel Cage

by Aleksandar Landović, Anka Starčev-Ćurčin, Miloš Šešlija and Danijel Kukaras

Buildings 2026, 16(4), 882; https://doi.org/10.3390/buildings16040882 - 23 Feb 2026

Viewed by 536

Abstract

The presented study investigates the structural behavior of reinforced concrete (RC) columns strengthened using an external steel cage and an additional concrete infill layer. An experimental program was conducted on short RC columns subjected to axial compressive force. A total of eleven columns [...] Read more.

The presented study investigates the structural behavior of reinforced concrete (RC) columns strengthened using an external steel cage and an additional concrete infill layer. An experimental program was conducted on short RC columns subjected to axial compressive force. A total of eleven columns were tested, including five plain RC and six strengthened specimens. The objective of the research was to evaluate the load-bearing capacity, failure mechanisms, and composite interaction between the steel cage, the infill concrete, and the original RC column. Two different distances between battens were considered in order to evaluate whether the number of batten plates significantly influences the efficiency of strengthening. The experimental results show that the proposed strengthening technique leads to an increase in axial capacity compared to unstrengthened specimens. Also, the variation in batten spacing within the investigated range has a negligible effect on the ultimate load. Failure was governed by cracking and bond deterioration in the infill layer, followed by progressive loss of composite action. The results indicate that the strengthening performance is primarily controlled by the properties of the infill concrete and the confinement mechanism, rather than by the spacing of the steel battens. The application of EN 1994-1-1 and EN 1998-3 in predicting the axial capacity of strengthened columns showed a good relation between experimental results and code calculations. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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24 pages, 3275 KB

Open AccessArticle

Multiple Regression and Neural Network-Based Models for the Prediction of the Ultimate Strength of CFRP-Confined Columns

by Baylasan Mohamad, Muna Hamadeh, Firas Al Mahmoud and George Wardeh

Infrastructures 2025, 10(12), 326; https://doi.org/10.3390/infrastructures10120326 - 1 Dec 2025

Viewed by 560

Abstract

Carbon Fiber-Reinforced Polymers (CFRPs) are gaining popularity as a reliable strengthening technique for reinforced concrete (RC) columns. Several efficient models were developed to predict the stress–strain (σ-ε) curve of CFRP-confined concrete based on experiment findings. The ultimate strength is a crucial parameter for [...] Read more.

Carbon Fiber-Reinforced Polymers (CFRPs) are gaining popularity as a reliable strengthening technique for reinforced concrete (RC) columns. Several efficient models were developed to predict the stress–strain (σ-ε) curve of CFRP-confined concrete based on experiment findings. The ultimate strength is a crucial parameter for accurate (σ-ε) behavior prediction, since it constitutes an initial step in estimating the corresponding axial strain, as it provides a direct indication of the desired increase in strength. Literature analytical models often produce inconsistent results due to errors in estimating the confinement pressure or effectively confined area or the lack of a strong and stable correlation between ultimate strength and confinement parameters. This study looked at a large collection of experimental results from existing research. It used a statistical method (Pearson’s coefficient) to see how well ultimate strength correlated with various confinement factors. For normal-strength concrete columns with circular sections, there was a strong linear correlation between ultimate strength and the thickness of the CFRP jacket. This correlation weakened for high-strength concrete (HSC) and for rectangular columns. A sensitivity analysis was performed to identify the most influential confinement parameters, showing that the number of CFRP layers (n

\times

t) is the most dominant factor, particularly with normal-strength concrete (NSC) in circular columns, accounting for the vast majority of the variance in ultimate strength. Using multiple linear regression equations to predict ultimate strength was also explored; this method demonstrated the best performance with HSC in circular sections, but the results were less promising with NSC. Artificial Neural Networks (ANNs) were developed and trained on the built database, and four statistical metrics were computed for evaluation (R², RMSE, MAE, MRAE), proving highly accurate and superior to linear regression equations, with mean relative absolute errors MRAEs between 2.4–7.2% for ultimate strength prediction, opening new avenues for optimizing CFRP-strengthened element designs. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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28 pages, 5092 KB

Open AccessArticle

Hybrid Flexural Strengthening Technique of Reinforced Concrete Beams Using Fe-SMA and CFRP Materials

by Mohammadsina Sharifi Ghalehnoei, Ahad Javanmardi, Maria Rashidi and Andreas Lampropoulos

Buildings 2025, 15(22), 4039; https://doi.org/10.3390/buildings15224039 - 10 Nov 2025

Cited by 2 | Viewed by 1360

Abstract

This study proposes a hybrid flexural strengthening technique for reinforced concrete (RC) beams by combining the near-surface mounted (NSM) and externally bonded reinforcement (EBR) methods. In this technique, iron-based shape memory alloy (Fe-SMA) strips are used for the NSM component, while either a [...] Read more.

This study proposes a hybrid flexural strengthening technique for reinforced concrete (RC) beams by combining the near-surface mounted (NSM) and externally bonded reinforcement (EBR) methods. In this technique, iron-based shape memory alloy (Fe-SMA) strips are used for the NSM component, while either a carbon fiber reinforced polymer (CFRP) sheet or an Fe-SMA sheet is applied as the EBR component. The proposed hybrid-strengthening method aims to enhance the flexural load capacity and ductility of existing RC beams. To evaluate the effectiveness of the proposed method, numerical models were developed using ABAQUS software and validated against experimental results. A comprehensive numerical investigation was carried out on 52 RC beams, categorized into six groups with various hybrid-strengthening configurations. In addition, the effect of the prestressing of NSM Fe-SMA strips and the prestressing of EBR CFRP or EBR Fe-SMA sheet on the flexural performance of the beams was also examined. The results indicated that the hybrid-strengthening method significantly improved the cracking, yielding, and ultimate load capacities of the beams; however, in most cases, it reduced their deflection. Notably, prestressing the EBR Fe-SMA sheet in beams with higher reinforcement ratios produced a pronounced improvement in ductility. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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20 pages, 8594 KB

Open AccessArticle

Strength and Ductility Improvement of Low Confinement Spun Pile with Steel Jacket Strengthening

by Yuskar Lase, Mulia Orientilize, Widjojo Adi Prakoso, Jansen Reagen and Stevany Lydia Jedidjah Hugen

Infrastructures 2025, 10(10), 262; https://doi.org/10.3390/infrastructures10100262 - 3 Oct 2025

Viewed by 1326

Abstract

Spun piles adjacent to the pile cap need sufficient confinement to ensure the formation of plastic hinges during severe earthquakes. However, the high confinement ratio required for precast piles according to ACI 318-19 results in tightly spaced spirals, which are difficult to implement. [...] Read more.

Spun piles adjacent to the pile cap need sufficient confinement to ensure the formation of plastic hinges during severe earthquakes. However, the high confinement ratio required for precast piles according to ACI 318-19 results in tightly spaced spirals, which are difficult to implement. Since higher confinement is only needed at specific regions of the pile, external transverse reinforcement using steel jacketing has been proposed as an alternative solution. An experimental and numerical study was conducted to evaluate the effectiveness. The experimental results showed that the jacket enhanced both the strength and energy dissipation of the connection, but had only a minor effect on its ductility. A parametric study using finite element analysis was performed to investigate the parameters influencing connection behavior. The results indicated that variations in jacket thickness did not significantly impact the connection’s performance. A jacket height equal to 1.53 times the pile diameter was found to be the maximum effective height. It was also observed that higher axial loads led to a sudden loss of connection strength, thereby reducing ductility. Partial bonding between the jacket, grout, and pile was found to be acceptable within a certain range. The numerical analysis found that the steel jacket increases the ductility. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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20 pages, 4716 KB

Open AccessArticle

Experimental Study of the Effectiveness of Strengthening Reinforced Concrete Slabs with Thermally Prestressed Reinforcement

by Yannik Schwarz, David Sanio and Peter Mark

CivilEng 2025, 6(3), 49; https://doi.org/10.3390/civileng6030049 - 13 Sep 2025

Cited by 1 | Viewed by 2051

Abstract

Conventional strengthening measures for existing structures are usually not effective for the self-weight, which accounts for around 70% of the total load in reinforced concrete structures. Therefore, their effect on the overall load-bearing capacity is low. A self-weight-effective alternative for flexural strengthening is [...] Read more.

Conventional strengthening measures for existing structures are usually not effective for the self-weight, which accounts for around 70% of the total load in reinforced concrete structures. Therefore, their effect on the overall load-bearing capacity is low. A self-weight-effective alternative for flexural strengthening is the thermal prestressing of additional reinforcement installed on the structure. In this method, reinforcing bars are slotted into the tensile zone, embedded in filler material, and tempered from the outside. They are thermally stretched, and once cooling starts, the bond with the hardened filler prevents re-deformation. The induced prestressing force counteracts dead loads and relieves the tensile zone, making the additional bars effective for the self-weight. In this paper, the effectiveness of the strengthening method is experimentally investigated in the serviceability and the ultimate limit states. Experiments involve strengthening a reinforced concrete beam under load by a thermally prestressed additional bar. Moreover, two reference tests are made to evaluate the method. An unstrengthened beam characterizes the lower capacity limit. Another beam with the same reinforcement amount as the strengthened one, but completely installed at casting, serves as the upper benchmark. All beams are loaded until bending failure. The strengthening method is assessed by means of the load-bearing behavior, deflection, crack development, and the strains in the initial as well as the added reinforcement. The results demonstrate the effectiveness of the strengthening method. The thermally prestressed bar achieves an effective pre-strain of approximately. 0.4‰ by heating at about 70 °C. The induced prestressing force and associated compression reduce tensile cracks by approx. 45% and increase stiffness. The strengthened beam reaches the maximum load of the upper benchmark, but with about 33% less deflection. The filler, which also expands thermally, generates an additional prestressing force that is effective up to about 20% of the load capacity. Beyond this, the filler begins to crack and its effect decreases, but the pre-strain in the reinforcing bar remains until maximum load. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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12 pages, 1843 KB

Open AccessArticle

Case Study of PLC Synchronous Lifting Technology in Concrete Column Reinforcement: Design, Construction, and Monitoring

by Baozhong Wang, Sijia Qian, Sabiu Muhammad, Mengqi Xu, Zhengke Shao, Na Li and Erlu Wu

Buildings 2025, 15(17), 3003; https://doi.org/10.3390/buildings15173003 - 24 Aug 2025

Viewed by 1223

Abstract

Traditional support methods, such as full-frame scaffolding, often pose significant safety risks during the replacement of defective concrete. In contrast, the application of programmable logic controller (PLC) synchronous jacking technology combined with an encircling beam is an innovative approach to concrete replacement. However, [...] Read more.

Traditional support methods, such as full-frame scaffolding, often pose significant safety risks during the replacement of defective concrete. In contrast, the application of programmable logic controller (PLC) synchronous jacking technology combined with an encircling beam is an innovative approach to concrete replacement. However, there is currently a lack of effective theoretical guidance for determining its design parameters, and there are also few measured data available to verify its effectiveness. To address this issue, this study investigates a concrete structure in which it was discovered, during the topping-out phase, that the compressive strength of several load-bearing columns did not meet the design specifications. Through structural analysis and load calculations, a reinforcement scheme utilizing the synchronous jacking system in conjunction with an encircling beam was proposed to replace the defective concrete. The monitoring of the settlement and deformation during the replacement process revealed a minimal settlement of 0.45 mm, which is approximately 23% of the predefined warning threshold. The results demonstrate that the integration of the synchronous jacking system with an encircling beam offers a safe and reliable solution, thus providing an effective approach to addressing similar challenges in concrete structural reinforcement. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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22 pages, 8767 KB

Open AccessArticle

Experimental and Numerical Investigation of Shear Performance of RC Deep Beams Strengthened with Engineered Cementitious Composites

by Hamsavathi Kannan, Sathish Kumar Veerappan and Madappa V. R. Sivasubramanian

Constr. Mater. 2025, 5(3), 51; https://doi.org/10.3390/constrmater5030051 - 31 Jul 2025

Cited by 2 | Viewed by 1377

Abstract

Reinforced concrete (RC) deep beams constructed with low-strength concrete are susceptible to sudden splitting failures in the strut region due to shear–compression stresses. To mitigate this vulnerability, various strengthening techniques, including steel plates, fiber-reinforced polymer sheets, and cementitious composites, have been explored to [...] Read more.

Reinforced concrete (RC) deep beams constructed with low-strength concrete are susceptible to sudden splitting failures in the strut region due to shear–compression stresses. To mitigate this vulnerability, various strengthening techniques, including steel plates, fiber-reinforced polymer sheets, and cementitious composites, have been explored to confine the strut area. This study investigates the structural performance of RC deep beams with low-strength concrete, strengthened externally using an Engineered Cementitious Composite (ECC) layer. To ensure effective confinement and uniform shear distribution, shear reinforcement was provided at equal intervals with configurations of zero, one, and two vertical shear reinforcements. Four-point bending tests revealed that the ECC layer significantly enhanced the shear capacity, increasing load-carrying capacity by 51.6%, 54.7%, and 46.7% for beams with zero, one, and two shear reinforcements, respectively. Failure analysis through non-linear finite element modeling corroborated experimental observations, confirming shear–compression failure characterized by damage in the concrete struts. The strut-and-tie method, modified to incorporate the tensile strength of ECC and shear reinforcement actual stress values taken from the FE analysis, was used to predict the shear capacity. The predicted values were within 10% of the experimental results, underscoring the reliability of the analytical approach. Overall, this study demonstrates the effectiveness of ECC in improving shear performance and mitigating strut failure in RC deep beams made with low-strength concrete. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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