Issue 39

S. Seitl et alii, Frattura ed Integrità Strutturale, 39 (2017) 118-128; DOI: 10.3221/IGF-ESIS.39.13 122 The B 1 curves are practically the same values for all five various materials. It only changes for values of relative crack length longer than α =0.5 (see Fig. 4). The functions of calibration curves for selected Young’s modulus of concrete E = 5, 20 and 100 GPa can be introduced as follows: B 1 ( E =5)= 5.5881 - 34.181α + 239.39α 2 - 594.79α 3 + 688.58α 4 - 251.61α 5 (6) B 1 ( E =20)= -2.3617 + 117.22α - 736.11α 2 + 2191.5α 3 - 2926.8α 4 + 1503.9α 5 (7) B 1 ( E =100)= -16.91 + 389.22α - 2465.6α 2 + 7030.8α 3 - 9049.3α 4 + 4371.4α 5 (8) Figure 4 : Values of dimensionless B 1 factor (stress intensity factor) versus a/W , the effect of elasticity modulus ratio (steel E =210 GPa). Figure 5 : Values of dimensionless B 2 factor ( T -stress) versus a/W , the effect of elasticity modulus ratio (steel E =210 GPa). Fig. 5 shows that the B 2 parameter changes practically negligibly, only for very low values of Young’s modulus E =5 GPa, there is relatively small deviation from another curves. 0 20 40 60 80 100 120 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 B 1 [‐] a/W [‐] E=5 GPa E=20 GPa E=60 GPa E=100 GPa ‐0,4 ‐0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 B 2  [‐] a/W [‐] E=5 GPa E=20 GPa E=60 GPa E=100 GPa