Overview of Factors Affecting the Behavior of Reinforced Concrete Columns with Imperfections at High Temperature

Mahmoud, Khaled Ahmed

doi:10.1007/s10694-021-01180-4

Cited by 5 publications

(2 citation statements)

References 12 publications

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“…In simulating RC slender columns, initial imperfections should be considered (Aristizabal-Ochoa, 2013;Harvey Jr. and Cain, 2020;Mahmoud, 2022;Tomski and Podgórska-Brzde ˛kiewicz, 2011). A number of trials with several initial imperfections including L/1000, L/900, L/800, L/700 L/ 600, L/500, and L/400 at the mid-height were conducted.…”

Section: Finite Element Modelingmentioning

confidence: 99%

Experimental and numerical investigations of precast circular reinforced concrete slender columns with intermediate connection

Hamoda,

Ahmed,

Abadel

et al. 2023

Advances in Structural Engineering

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This paper carries out experimental and numerical investigations on the axial performance of circular Reinforced Concrete (RC) precast slender columns with an intermediate connection. A series of tests are carried out to study the effects of longitudinal reinforcement ratio (ρ), and embedded length of steel bars (Lb) of precast columns on their axial performance under concentric loading. Test results show that increasing the reinforcement ratio and the embedded length of the precast columns significantly improves the axial performance of the precast slender columns. Nonlinear finite element models (FEM) are developed to simulate the performance of the columns experimentally observed. The accuracy of the FEM is validated against the test results and found to reasonably predict the axial performance of tested columns.

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Section: Finite Element Modelingmentioning

confidence: 99%

Experimental and numerical investigations of precast circular reinforced concrete slender columns with intermediate connection

Hamoda,

Ahmed,

Abadel

et al. 2023

Advances in Structural Engineering

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“…Due to the influence of the external environment, concrete buildings are often exposed to high-temperature conditions, such as hot areas, fires, geothermal heat, etc. The performance of concrete materials is affected by high temperatures, and many experts and scholars have carried out research in this field [1][2][3][4][5][6]. Miao et al.…”

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confidence: 99%

Experimental study on mechanical properties and breakage of high temperature carbon fiber-bar reinforced concrete under impact load

Wang,

Lv,

et al. 2024

Preprint

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To investigate the effects of high temperature and carbon fiber-bar reinforcement on the dynamic mechanical properties of concrete materials, a muffle furnace was used to treat two kinds of specimens, plain and carbon fiber-bar reinforced concrete, at high temperatures of 25, 200, 400 and 600 ℃. Impact compression tests were carried out on two specimens after high-temperature exposure using a Hopkinson pressure bar (SHPB) test setup combined with a high-speed camera device to observe the crack extension process of the specimens. The effects of high temperature and carbon fiber-bar reinforcement on the peak stress, energy dissipation density, crack propagation and fractal dimension of the concrete were analyzed. The results showed that the corresponding peak strengths of the plain concrete specimens at 25, 200, 400, and 600°C were 88.37, 93.21, 68.85, and 54.90 MPa, respectively, and the peak strengths after the high-temperature exposure first increased slightly and then decreased rapidly. The mean peak strengths corresponding to the carbon fiber-bar reinforced concrete specimens after high-temperature action at 25, 200, 400, and 600°C are 1.13, 1.13, 1.21, and 1.19 times that of plain concrete, respectively, and the mean crushing energy consumption densities are 1.27, 1.31, 1.73, and 1.59 times that of plain concrete, respectively. The addition of carbon fiber-bar reinforcement significantly enhanced the impact resistance and energy dissipation of the concrete structure, and the higher the temperature was, the more significant the increase. An increase in temperature increases the number of crack extensions and width, and the high tensile strength of the carbon fiber-bar reinforcement and the synergistic effect with the concrete material reduce the degree of crack extension in the specimen. The fractal dimension of the concrete ranged from 1.92 to 2.68, that of the carbon fiber-bar reinforced concrete specimens ranged from 1.61 to 2.42, and the mean values of the corresponding fractal dimensions of the plain concrete specimens after high-temperature effects at 25, 200, 400, and 600°C were 1.19, 1.21, 1.10, and 1.11 times those of the fiber-reinforced concrete specimens, respectively. The incorporation of carbon fiber-bar reinforcement reduces the degree of rupture and fragmentation of concrete under impact loading and improves the safety and stability of concrete structures.

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A Simplified Method for Determining Fire Resistance of RC Columns Using Fire-Resistance-Column-Curves Approach

Mahmoud

2024

Fire Technol

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Eurocode-2 (EC2) empirical equation for fire resistance of RC columns is very sensitive to the value of column capacity at normal temperature conditions $$N_{Rd}$$ N Rd . Techniques to determine $$N_{Rd}$$ N Rd accurately for eccentric slender columns are difficult and computationally demanding; thus, adopting simplifications leads to unsatisfactory results in many column cases. Another shortcoming of EC2 equation is that it does not include an explicit term regarding the effect of load eccentricity on fire resistance. In this paper, a simplified method, as an attempt to overcome EC2 method defects, is developed to determine the fire resistance of RC columns using fire-resistance-column-curves. A rational numerical model is used to analyze various series of RC columns with different geometric, material, and loading properties at elevated temperatures. The results of the numerical study are utilized to construct different fire-resistance-column-curves from which simplified design equations are developed to predict the fire resistance of fixed- and pinned-end RC columns. The validity of the method is established with the aid of experimental data and it was found that in most cases, there is good agreement between assessed and test columns. It was also found that the proposed equations provide sufficiently safe predictions when appropriate material safety factors are adopted. The applicability of the proposed method to fire resistance design of RC columns is illustrated through numerical examples.

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Overview of Factors Affecting the Behavior of Reinforced Concrete Columns with Imperfections at High Temperature

Cited by 5 publications

References 12 publications

Experimental and numerical investigations of precast circular reinforced concrete slender columns with intermediate connection

Experimental and numerical investigations of precast circular reinforced concrete slender columns with intermediate connection

Experimental study on mechanical properties and breakage of high temperature carbon fiber-bar reinforced concrete under impact load

A Simplified Method for Determining Fire Resistance of RC Columns Using Fire-Resistance-Column-Curves Approach

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