Characteristics of Elastic Wave in Fire damaged High Strength Concrete using Impact-echo Method

Lee, Jun Cheol; Lee, Chang Joon; Kim, Wha Jung; Lee, Ji Hee

doi:10.7731/kifse.2015.29.1.001

Cited by 2 publications

(4 citation statements)

References 12 publications

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“…Figure 10 shows typical time signals measured by IE testing on the surface of reinforced concrete slab specimens before and after the 3-h standard fire testing. Consistent with the observations made by previous researchers [15,16,19,22,25], the time signals measured on the concrete surface exposed to fire (Figure 10b) were dominated by waves with longer wavelengths than those measured on the sound concrete (Figure 10a). Furthermore, some differences were also observed in the time signal measured on the surface opposite the fire exposure side, compared to that measured on the sound concrete.…”

Section: Typical Signals From Impact-echo Testingsupporting

confidence: 91%

“…Therefore, the data scans represent a total of 100 test points on the surface of the damaged concrete slab specimen. In addition, the IE testing was performed at five locations, (x, y) = ((4, 3), (8,3), (12,3), (16,3), (20,3)), at the top (or the opposite surface to the fire-exposed surface) of the firedamaged concrete slab specimen, to compare the spectral responses from the exposed and the opposite surfaces of the concrete slab. Figure 7a and b show pictures from the IE testing on the solid concrete and fire-damaged concrete slab specimens, respectively.…”

Section: Test Setup and Procedures For Impact-echo Testingmentioning

confidence: 99%

“…It has been shown that the P-wave velocity of concrete is a good indicator for evaluating the chemical and mechanical changes in fire-damaged concrete [ 9 , 10 , 11 ]. Some researchers investigated the variations in the resonance frequencies of regularly shaped concrete specimens (cylinders or prisms) with various maximum exposure temperatures [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. Recently, the authors investigated the variations in the dynamic mechanical properties of concrete (elastic modulus and Poisson’s ratio) for nuclear power plants in Korea using ultrasonic pulse velocity measurements and resonance frequency tests [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

“…Figure16. Several possible wave paths of non-propagating waves in solid and fire-damaged concrete slabs: (a,b,d) are the multiple reflections of P-waves between the two free surfaces on solid concrete slabs and the fire-damaged concrete slabs, caused by an impact source on either surface of the concrete slab specimen (the bottom surface for (a,b), and the top surface for (d)); (c,e) show the multiple reflections of P-waves between a free surface and an internal acoustic reflector at a high impedance mismatch, generated by an impact source on the bottom surface and top surface, respectively.The peak frequency of the thickness stretch mode in the fire-damaged concrete slab was approximated as follows:,…”

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confidence: 99%

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Interpretation of Impact-Echo Testing Data from a Fire-Damaged Reinforced Concrete Slab Using a Discrete Layered Concrete Damage Model

Lee

Kee

Kang

et al. 2020

Sensors

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The main objectives of this study are to investigate the spectral responses of a fire-damaged concrete slab using Impact-echo (IE) testing, and to develop a simplified model for interpreting the frequency shift due to heat-induced concrete damage after the fire. For these purposes, a reinforced concrete slab specimen (1000 mm (width) by 5000 mm (length) by 210 mm (thickness)) was fabricated in the laboratory. Heat damage in the concrete slab specimen was induced by exposing the bottom of the specimen to the temperatures corresponding to the standard fire curve described in the ASTM E 119 for 3 h. Impact-echo testing was performed on the bottom surface of the concrete slab specimen before and after inducing the fire damage. It was observed that the spectral responses of the fire-damaged concrete were dominated by several non-propagating waves, which resulted in main peak frequencies around 4500 Hz and 5100 Hz. A discrete layered concrete damage model developed in this study was used to reconstruct the variation of the P-wave velocity with the depth of the fire-damaged concrete. It was demonstrated that the predicted P-wave velocity profile using the simplified model showed a good agreement with the measured values from the five core samples, which measured 100 mm (diameter) by 200 mm (height) cylinders, using ultrasonic pulse velocity (UPV) measurements at eight different depths. In addition, the peak frequencies predicted by the simplified model were consistent with the measured peak frequencies. The experimental results in this study demonstrated that IE testing is effective for evaluating the post-fire damage of reinforced concrete slabs. Particularly, the simplified model in this study can be effective for better interpreting the spectral responses of fire-damaged concrete slabs by IE testing.

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Section: Typical Signals From Impact-echo Testingsupporting

confidence: 91%

Section: Test Setup and Procedures For Impact-echo Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Interpretation of Impact-Echo Testing Data from a Fire-Damaged Reinforced Concrete Slab Using a Discrete Layered Concrete Damage Model

Lee

Kee

Kang

et al. 2020

Sensors

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Factors Influencing Measurement of Dynamic Elastic Modulus from Disk-Shaped Concrete Specimen

Kim,

Son,

Chung

et al. 2024

Int J Concr Struct Mater

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The decrease in dynamic elastic modulus is a primary indicator of quantitative damage in concrete. To quantitatively assess depth-by-depth damage within a concrete structure, cylindrical specimens obtained through coring can be cut into disk specimens to measure the dynamic elastic modulus of concrete at each depth. To minimize external damage during coring, it is essential to extract cylinders with the smallest possible diameter. In addition, for higher resolution in depth-based damage assessment, creating disk specimens with the smallest possible thickness is necessary. However, there is no information available in the literature on experimental limitation of smallest possible diameter and thickness for dynamic elastic modulus of disk-shaped specimens. This study evaluated whether the dynamic modulus measured from various sizes of concrete disk specimens provided sufficient reliability compared to reference values obtained from cylinders. Moreover, the study examined how the presence of coarse aggregate and variation in the water–cement ratio significantly influenced the dynamic modulus measurement. In addition, test results from impulse excitation technique (IET) and impact resonance (IR) were compared to find a more reliable test method for dynamic elastic modulus of disk specimen. The experimental findings revealed that as the thickness-to-radius ratio of the disk specimens decreased, measured data variation increased. Mortar specimens without coarse aggregates showed less variability compared to concrete specimens, and the variation in dynamic modulus measured by IR was lower than that measured by IET.

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Characteristics of Elastic Wave in Fire damaged High Strength Concrete using Impact-echo Method

Cited by 2 publications

References 12 publications

Interpretation of Impact-Echo Testing Data from a Fire-Damaged Reinforced Concrete Slab Using a Discrete Layered Concrete Damage Model

Interpretation of Impact-Echo Testing Data from a Fire-Damaged Reinforced Concrete Slab Using a Discrete Layered Concrete Damage Model

Factors Influencing Measurement of Dynamic Elastic Modulus from Disk-Shaped Concrete Specimen

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