Analysis of RC columns strengthened with ultra-high performance fiber reinforced concrete jackets under eccentric loading

Sakr, Mohammed A.; Korany, Tamer M. El; Osama, Bothaina

doi:10.1016/j.engstruct.2020.111016

Cited by 28 publications

(10 citation statements)

References 53 publications

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“…where t is the nominal voltage vector, K is the elastic stiffness matrix, and ε is the nominal strain vector. According to Nguyen and Kim 41 and Sakr et al 27 the rigidity K nn was considered as 0:1E c ; K ss and K tt are defined as 0:1G c , being E c and G c the elasticity and shear modulus of concrete, respectively. The shear modulus was expressed by Equation 20.…”

Section: Modeling the Interaction Between Materialsmentioning

confidence: 99%

Effect of ultra‐high performance concrete repair layer thickness on the behavior of concrete columns

Tolentino,

dos Santos,

Poncetti

et al. 2023

Structural Concrete

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The use of ultra‐high‐performance fiber reinforced concrete (UHPFRC) to repair or rehabilitate old concrete structures has been shown to be appropriate due to its properties, such as higher compressive strength, ductility, and durability than conventional concretes. One of the studied strengthening techniques is the reinforced concrete columns jacketing by UHPFRC. Some recent research evaluated some parameters, such as the repair thickness and the volumetric ratio of stirrups. However, other important parameters, such as UHPFRC jacketing thickness in different column cross‐sections and the concrete core compressive strength, need to be addressed. In addition, the analytical models presented in the literature are restricted to only one concrete grade. The present study aims to evaluate the behavior of short reinforced concrete columns strengthened with UHPFRC subjected to centered compression. Numerical analyses of three‐dimensional models were performed using the finite element method, validated, and calibrated using experimental results. The influence of the concrete core compressive strength, the UHPFRC jacketing thickness, and the shape of the cross‐section were evaluated. Numerical simulations concluded that the lower concrete core compressive strength columns showed the best relative increase performance. Moreover, the concrete core strength was inversely proportional to the resistance capacity of the repair system. In addition, the increase in repair thickness contributes to the axial strength of the column. Furthermore, the cross‐section influences the distribution of stresses and strains, showing the best performance for circular sections. Finally, regardless of cross‐section type, the proposed equations accurately predicted the numerical results.

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Section: Modeling the Interaction Between Materialsmentioning

confidence: 99%

Effect of ultra‐high performance concrete repair layer thickness on the behavior of concrete columns

Tolentino,

dos Santos,

Poncetti

et al. 2023

Structural Concrete

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“…Furthermore, the failure of the specimens occurs in two directions (X and Y) only. Consequently, the FE procedures presented hereinafter are for the 2D model as it has much less computational time compared with the 3D model (Sakr et al, 2019(Sakr et al, , 2020(Sakr et al, , 2021. The proposed 2D FE model can mimic the performance of exterior beam-column joints under cyclic loading considering non-linear material, post-peak behavior (negative tangent stiffness), and damage.…”

Section: Finite Element Modelmentioning

confidence: 99%

Analysis of exterior beam-column joints under varying column axial load and code comparisons

Sakr

Saad

Elkorany

2022

Advances in Structural Engineering

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This paper presents a finite element (FE) study of beam-column joints subjected to cyclic loading. This study is primarily dependent on investigating the shear behavior of joints under the influence of different column axial load ratios. Wherefore, a total range of the column axial load ratios, whether in tension or compression has been considered. This paper proposes a two-dimensional (2D) FE model that considers material non-linearity. The proposed FE model was verified with experimental results from literature that tested varying column axial load ratios and different failure modes. The examination among experiential and numerical outcomes demonstrated that the FE model can reenact the conduct of beam-column joints and can catch the different failure modes with acceptable accuracy. A parametric study was established using the proposed FE model and strut-and-tie (ST) model of Pauletta to assess the Eurocode joint shear strength equations. For this purpose, four specimens were designed according to Eurocode recommendations while two other specimens were designed to satisfy all of the Eurocode recommendations except for the required joint confinement. An interaction diagram was introduced for each specimen to express the behavior under varying column axial load ratios. The results of the comparison between Eurocode, FE model, and ST model showed some differences in calculating the joint shear strength capacity, especially under column tension loads. Furthermore, this paper proposed new design equations based on Eurocode equations taking into account the column axial load effect. These proposed equations worked to increase the accuracy in calculating the joint shear strength capacity. Proposed equations were compared to the FE model results and other experimental results available in the literature. The comparison showed that the differences with the FE model decreased and that the proposed equations had better accuracy at different tension and compression loads than the Eurocode.

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“…Therefore, recent studies have been conducted on seismic hooks and steel wire mesh (SWM) to improve the shear performance of the jacketing section and on the use of dowels to constrain the jacketing section and the old section [ 1 , 2 , 3 ]. Many studies focused on improving the strength of the jacketing section using ultra-high-performance fiber-reinforced concrete (UHPFRC) have been conducted [ 4 , 5 , 6 , 7 ]. UHPFRC can show excellent strength, ductility and durability by lowering the water-binder ratio (W/B) by 20% and mixing high-powder admixtures and high-strength steel fibers.…”

Section: Introductionmentioning

confidence: 99%

“…Slip occurs at the interface between the core and the jacket concrete if the bonding is not properly secured when a load is applied to the reinforced concrete columns, so the seismic performance of the jacketing section is expected to be unacceptable. There are limited published studies on the contact surfaces of reinforced concrete members and jacketing [ 6 ]. Furthermore, when dealing with members having connections, it is important to conduct investigations to identify potential factors that could impact the monolithic behavior, such as slippage [ 10 , 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Improved Shear Strength Equation for Reinforced Concrete Columns Retrofitted with Hybrid Concrete Jackets

Kim

Lee

2023

Materials

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The adequacy of retrofitting with concrete jacketing is influenced by the bonding between the old section and jacketing section. In this study, five specimens were fabricated, and cyclic loading tests were performed to investigate the integration behavior of the hybrid concrete jacketing method under combined loads. The experimental results showed that the strength of the proposed retrofitting method increased approximately three times compared to the old column, and bonding capacity was also improved. This paper proposed a shear strength equation that considers the slip between the jacketed section and the old section. Moreover, a factor was proposed for considering the reduction in the shear capacity of the stirrup resulting from the slippage between the mortar and stirrup utilized on the jacketing section. The accuracy and validity of the proposed equations were examined through a comparison with the ACI 318-19 design criteria and test results.

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Analysis of RC columns strengthened with ultra-high performance fiber reinforced concrete jackets under eccentric loading

Cited by 28 publications

References 53 publications

Effect of ultra‐high performance concrete repair layer thickness on the behavior of concrete columns

Effect of ultra‐high performance concrete repair layer thickness on the behavior of concrete columns

Analysis of exterior beam-column joints under varying column axial load and code comparisons

Improved Shear Strength Equation for Reinforced Concrete Columns Retrofitted with Hybrid Concrete Jackets

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