PSI - Issue 59

Olena Romashko-Maistruk et al. / Procedia Structural Integrity 59 (2024) 352–359 O. Romashko-Maistruk and V. Romashko/ Structural Integrity Procedia 00 (2023) 000 – 000

357

6

2 / )) /9) ((1 log( s     

6 1 10    s   ,

(7)

for

u DIF DIF 

where   is the strain rate of compressed concrete under the action of dynamic loads; s   - the maximum strain rate of compressed concrete under the action of quasi-static loads, 5 1 10    s s   . The effectiveness of the developed methodology for determining the dynamic increase factor of compressed concrete was evaluated by comparing the results of theoretical calculations according to expression (7) with individual researcher’s experimental data (Cowell (1966), Kono et al. (2001)). It is displayed on the graphs of Fig. 4-7. At the same time, similar comparisons were made with the results of calculations performed according to the methods of the CEB-FIP (1991) and fib (2012). All of them show that the priority in the accuracy of determining the DIF belongs to the proposed method, which is based on the concrete and reinforced concrete energy model (Romashko and Romashko (2019), Romashko and Romashko-Maistruk (2022)).

2

1.5

1

Dynamic increase factor (DIF)

0.5

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01

Strain rate of concrete ( έ )

Fig. 4. Dependence of DIF on the strain rate of compressed concrete with strength

: - according to experiments Cowell (1966);

f c 26.89 

MPa

–– - according to formula (7); – – - according to CEB-FIP (1991).

2

1.5

1

Dynamic increase factor (DIF)

0.5

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01

Strain rate of concrete ( έ )

Fig. 5. Dependence of DIF on the strain rate of compressed concrete with strength

: - according to experiments Cowell (1966);

f c 60.32 

MPa

–– - according to formula (7); – – - according to CEB-FIP (1991).