Issue 43

E. Maiorana et alii, Frattura ed Integrità Strutturale, 43 (2018) 205-217; DOI: 10.3221/IGF-ESIS.43.16 216 Figure 14 : F Si [kN] vs.  Comparison between RCSC [3] ( ) and EN [2] ( ). Results of series from CNR [20] are not included in the diagram. The trend of the curve shows an increase of  with F Si and considering the slip coefficient from tests by EN [2], if the results of µ m are multiplied by 1.5, the obtained valued are in line with the coefficient by RCSC [3]. Fig. 15 shows all the single results with the test method as in EN [2]. The higher values were found maximizing the roughness of the surfaces and the tightening torque. Figure 15 : F Si [kN] vs.  i for the EN [2] method. C ONCLUSION he results of comparison and experimental tests on coating products regarding the evaluation of the slip factor for only sandblasted and sandblasted-coated surfaces are reported. Considering test for the determination of the slip factor, EN [2], contrary to RCSC [3] which assume a value  =  m , adopts the characteristic value  k taking into account the standard deviation within the tests and in conclusion the mean value  m is reduced by about 10% also considering that the partial safety factor applied to the design slip resistance is 1.25; 1.5 for RCSC [3]. The improvement regards the following aspects: - An increase in the  i value was observed with the percentage of zinc in the coating component. Also an increase was obtained applying a greater tightening torque that is, on the other hand, considering in the calculation a greater k -factor. Alternatively, using grease between the screw and the nut, to consider a tightening force 1.1 M s is suggested. - Making a comparison between RCSC [3] and EN [2] in terms of experimental applied force F Si vs.  , for both American and European standards,  increases with F Si , but with RCSC [3] a greater value of  is observed than that of EN, of about 10%, because test setup and the method to calculate  are different. In term of  m the ratio is 1.5. - The trend of F Si respect  i shows an increase in the slip factor with the applied force, thus to obtain a greater slip factor it is necessary to increase the roughness of the surfaces and the tightening torque. T