Zusammenwirken von Faser- und Betonstahlbewehrung bei biegebeanspruchten UHPC-Bauteilen

Ultra high performance concrete (UHPC) offers great potential in terms of sustainable solutions for rehabilitation and strengthening of existing structures as well as resource-saving new constructions. In this context, the combination of fibre and ordinary reinforcement can be very effective due to the synergy effects regard-ing crack width limitation and braking of load drop after deformation localisation. Bending tests with different cross-section geometries and reinforcement combinations were carried out in order to confirm this assessment. Thanks to modern measuring methods, the crack width development could be continuously recorded over the entire test sequence, even for very fine cracks. The results show that the full effect of the reinforcing steel (yield strength) and the fibre reinforcement (post-cracking tensile strength) can be added together for the determination of the load-bearing capacity; independent of the fibre content. Furthermore, a simplified approach for the calculation of crack widths in the serviceability limit state was derived on the basis of the obtained measurement data.