• International Journal of Highway Engineering
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• v.20 no.3
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• pp.39-46
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• 2018

PURPOSES: This study is to estimate nondestructive strength equation based on probability for bridges using field test data. METHODS : In this study, a series of the field inspection and the test have been performed on 297 existing bridges, in order to evaluate the bridges, based on the test results of the in-depth inspection, and the estimated strengths by means of the nondestructive strength equations are analyzed and compared with results of the core specimen strengths. RESULTS : According to results of analyses, In case of standard design compressive strength of concrete is 18MPa, 21MPa, similar reliability of RILEM equation were 0.89~0.90, but in case of standard design compressive strength of concrete is 35MPa, 40MPa were 0.4~0.56. According to standard design compressive strength of concrete is 40MPa, similar reliability of ultrasonic pulse velocity method equation were 0.56. CONCLUSIONS :RILEM equation had high similar reliability than other equation in case of standard design compressive strength of concrete is 18MPa, 21MPa, but had low similar reliability than other equation in case of standard design compressive strength of concrete is 35MPa, 40MPa. and ultrasonic pulse velocity method equation had low similar reliability than other equation in case of standard design compressive strength of concrete is 40MPa.

• Journal of the Korea Institute of Building Construction
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• v.2 no.3
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• pp.123-130
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• 2002

Recently, it is being studied on the high strength concrete in many laboratories and being applied to the construction field actually. But non-destruction testing equation that to be proposed about normal strength concrete in Japan has been using because the systematic study results for the estimation of compressive strength of high strength concrete do nit exist. So it is essential to suggest the non-destruction testing equation for the estimation of compressive strength of high strength concrete. This is an experimental study to analyze and investigate the non-destruction testing equation for the estimation of compressive strength of high strength concrete. The results are as follows; The relation between rebound number, pulse velocity and compressive strength of high strength concrete have lower coefficient than combined method of rebound number and pulse velocity. Also new non-destructive testing equation for the estimation on the compressive strength of high strength concrete was suggested in this study, and it is considered that these equations have possibility to be applied in domestic construction field.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.139-140
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• 2015

The purpose of this study was to evaluate existing compressive strength equation with concrete exposed to high temperature by ultrasonic pulse velocity. As the result, original compressive strength equation is proper only for compressive strength of normal concrete. Therefore, an accumulation of experimental database of concrete exposed to high temperature is necessary for proposal of new compressive strength equation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.5-6
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• 2014

For estimating compressive strength of concrete, non-destructive test has conducted generally. It used experimental equation to calculate compressive strength from construction. This study investigated experiment to apply non-destructive test, based on fresh property, compressive strength and ultrasonic pulse velocity of high performance concrete. And it conducted to compare various proposed equation.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.63-71
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• 1999

In evaluating the ultimate strength of a section for a reinforced concrete flexural member, the effect of member length is not usually considered, even though the strength tends to decrease with increase of member length. In this paper the influence of specimen length on flexural compressive strength of concrete was evaluated. For this purpose, a series of C-shaped specimens subjected to axial compression and bending moment were tested using four different length-to-depth ratios (from 1,2,3 and 4) of specimens with compressive strength of 590 kgf/$\textrm{cm}^2$. Results indicate that for the region of h/c <3.0 the reduction in flexural compressive strength with increase of length-to-depth ratios was apparent. A model equation was depth of an equivalent rectangular stress block was larger than that by ACI. It was also founded that the effect of specimen length on ultimate strain was negligible. Finally more general model equation is also suggested.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.155-161
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• 2003

This paper presents experimental and analytical results of glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PERC) to investigate the relationship between tensile strength and compressive strength based on the split cylinder test (ASTM C496) and compressive strength test (ASTM C39). Experimental studies were performed on cylinder specimens having 150 mm in diameter an 300 mm in height with two different fiber contents (1.0 and 1.5％ by volume fraction) at ages of 7, 28 and 90 days. A total of 90 cylinder specimens were tested including specimens made of the plain concrete. The experimental data have been used to obtain the relationship between tensile strength and compressive strength. A representative equation is proposed for the relationship between tensile strength and compressive strength of fiber-reinforced concrete (FRC) including glass and polypropylene fibers. There is a good agreement between the average experimental results and those calculated values from the proposed equation.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.121-130
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• 2000

Currently, in evaluating a flexural strength of a concrete member, the effect of specimen depth has not been systematically studied, even though its effect on ultimate strength of a section is very important. For all types of loading conditions, the trend is that the strength of a member tends to decrease when the member depth increases. In this study, the influence of specimen depth on flexural compressive strength of concrete member was examined experimentally. A series of C-shaped specimens subjected to axial compressive force and bending moment were tested using three geometrically similar specimens with different length-to depth ratios (h/c = 1, 2 and 4) which have compressive strength of 55 MPa. The results indicate that the flexural compressive strength decreased as the specimen depth increased. A model equation was derived based on regression analyses of the experimental data. Also, the results show that ultimate strain decreases as the specimen depth increases. Finally, a general model equation for the depth effect is proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.115-120
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• 2000

Currently, in evaluating a flexural strength of a concrete member, the effect of specimen depth has not been systematically studied, even though its effect on ultimate strength of a section is very important. For all types of loading conditions, the trend is that the strength of a member tends to decrease when the member depth increases. In this study, the influence of specimen depth on flexural compressive strength of concrete member was examined experimentally. A series of C-shaped specimens subjected to axial compressive force and bending moment were tested using three geometrically similar specimens with different length-to-depth ratios(h/c=1, 2 and 4) which have compressive strength of 55MPa. The results indicate that the flexural compressive strength decreased as the specimen depth increased. A model equation was derived based on regression analyses of the experimental data. Also the results show that ultimate strain decreases as the specimen depth increases. Finally, a general model equation for the depth effect is proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.123-130
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• 2001

The purpose of this study is to suggest the non-destructive equation for the estimation of concrete strength by ultrasonic pulse velocity at the Age of 28day compressive strength of $600{\sim}1000kg/cm^2$. For this purpose, selected test variables were water-hinder ratio, replacement ratio of silica fume, binder content, maximum size of coarse aggregate and sand-aggregate ratio. From the results, the average increase or decrease of ultrasonic pulse velocity is 61m/sec for each 1% of moisture content. And the correlation equation between the ultrasonic pulse velocity and the compressive strength of concrete is as follows. $F_c=896.3V_p-3514$ ($R^2$ = 0.81) where, $F_c$ : compressive strength($kgf/cm^2$), $V_p$ : ultrasonic velocity(km/sec).

• Journal of the Korean Institute of Gas
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• v.21 no.3
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• pp.26-32
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• 2017

Outer tank concretes of LNG storage tank are composed of prestressed concrete structures that act as a protective wall. The danger such as the collapse of structures will exist if concrete structures is not secured due to the deterioration. Concrete compressive strength directly related to the safety of structures can be predicted by using estimation equation of compressive strength through rebound hardness test and ultrasonic wave velocity method. But, there is no the estimation equation of LNG storage tank for a relation between NDT data and real strength. In this study, to obtain more accurate real strengths for LNG storage tank, core specimens were sampled from walls of pilot LNG storage tank. The rebound hardness test of general NDT for concrete structures was carried out at each 3 positions for the four areas. The compressive strength estimation equation of LNG storage tank was developed by using the data for rebound hardness test of pilot LNG storage tank and compressive strength test of sampled concrete cores.