Calculation of crack width of concrete components reinforced with steel fibres and reinforcing bars

摘要

According to the current state of the DAfStb guideline "steel fibre concrete", the calculation of crack width of components made of steel fibre concrete with reinforcing bars is carried out using the residual tensile strength of performance class L2 (L2 value). The L2 value is used in the DAfStb guideline for the ultimate limit state, although the implementation of the residual tensile strength in the performance class L1 (L1 value) would be more applicable, since it is characteristic for the serviceability limit state. Due to the limited number of tests and missing evaluations, however, the use of the L2 value for the calculation of crack width was specified in the DAfStb guideline on the so-called "safe side". For a more detailed investigation of the applicable residual tensile strength value for the calculation of crack widths, the approach according to DAfStb guideline has been compared with national and international test data of steel fibre concrete with reinforcing bars at the iBMB, Division of Concrete Construction of TU Braunschweig. Furthermore, a comparison between experimental and calculated crack widths of reinforced concrete components without steel fibres was carried out using the approach of DIN EN 1992-1-1 in conjunction with DIN EN 1992-1-1/NA. The investigation results show almost the same prediction level by the crack width calculation approach according to DAfStb guideline with L1 value as by the calculation approach of DIN EN 1992-1-1 in conjunction with DIN EN 1992-1-1/NA.