Dr.-Ing. Sara Javidmehr
Effect of mechanical degradation of concrete on structural response of reinforced concrete construction
The growing load demand on existing bridges together with mechanical deterioration of materials under cyclic loading and inherent deficiencies increase the demand on structural assessments. An exact estimation of existing bearing capacities is therefore the aim of these structural assessments. One of these bearing capacities is the tensile capacity of concrete. In the case of existing bridges, consideration of effects of aging under cyclic loads on concrete tensile capacity is essential for a safe structural assessment.
Within this research project, a material model should be developed for tensile capacity of concrete considering effects of aging (mechanical degradation). Based on experiments under cyclic loading, damage ratio of the specimens would be determined and their remaining load bearing capacity would be demarcated. Due to the ongoing discussions on shear capacity of concrete members, the developed model would be used for studying the role of stress and time-dependent concrete tensile capacity on structural behaviour of RC-members under shear loads. Based on the experimental investigations, new concepts would be developed for estimation of remaining load bearing capacity of existing bridges.
Publications within the framework of the RTG:
Doctoral thesis:
S. Javidmehr. Shear Capacity of Concrete Members under Monotonic and Cyclic Diagonal Tension.
Publications in peer-reviewed scientific journals:
S. Javidmehr; M. Empelmann: Schrägrissbildung von Stahlbetonbalken unter zyklischer Querkraftbeanspruchung/Diagonal cracking of reinforced concrete beams under cyclic shear loading. Bauingenieur 96(04):132-141, 2021. DOI: 10.37544/0005-6650-2021-04-68
J. P. Lanwer; S. Javidmehr, S.; M. Empelmann: Statistische Bewertung der Druckfestigkeit von ultrahochfestem Beton (UHFB)/ Statistical evaluation of compressive strength of ultra-high strength concrete. In: Beton- und Stahlbetonbau 116 (2021), DOI: 10.1002/best.202000103
J. Cramer, S. Javidmehr and M. Empelmann. Simulation of Crack Propagation in Reinforced Concrete Elements. Applied Sciences 11, no. 2, 785, 2021. https://doi.org/10.3390/app11020785 (open access)
M. Empelmann and S. Javidmehr. Practical determination of the factor α cc. In: Beton- und Stahlbetonbau 115 (2020), Heft 8, S. 560-565.
M. Empelmann and S. Javidmehr. Sustained load behaviour of normal-strength concrete. In: Beton- und Stahl-betonbau 115 (2020), Heft 4, S. 260-269.
S. Javidmehr, V. Oettel and M. Empelmann. Schrägrissbildung von Stahlbetonbalken unter Querkraftbeanspruchung. Bauingenieur 93, Heft 6, S. 248-254, 2018.
S. Javidmehr. Zugtragwirkung von Beton bei der Querkrafttragfähigkeit von Bestandsbrücken. Beton- und Stahlbetonbau 112, Heft 7, S. 455, 2017.
Conference contribution with publication in conference proceedings:
Empelmann, M.; Javidmehr, S.: Evaluation of concrete compression failure under high sustained loads. In: Zhao, B.; Lu, X. (Ed.): Proceedings of the fib Symposium 2020, 22.-24.11.2020 in Shanghai (China), S. 827-834 (Online-Conference).
S. Javidmehr and M. Empelmann. Diagonal cracking load of concrete members without shear reinforcement. Proceedings of the 12th fib International PhD Symposium in Civil Engineering, S. 457-465, Prag, 2018.
S. Javidmehr and M. Empelmann. Zugtragwirkung von Beton bei der Querkrafttragfähigkeit von Bestandsbrücken - Bestimmung der Schrägrisslasten unter Querkraftbeanspruchung. Beiträge zur 5. DAfStb-Jahrestagung mit 58. Forschungskolloquium, Band 2, S. 1-11, Kaiserslautern, 2017.
D. Busse and S. Javidmehr. Schubtragfähigkeit bestehender Brücken - Potenziale alternativer Nachweisformate. Seminarband zum VSVI-Seminar Nr. 10 "Brücken- und Ingenieurbau", S. 21-28, Braunschweig, 2016.
Additional literature:
D. Busse, L. Eckfeld and M. Empelmann. Assessing the reliability of existing concrete bridges in terms of shear strength. Proceedings of the 5th International Conference on Structural Engineering, Mechanics and Computation (SEMC 2013), Cape Town, South Africa, 2013.
G. Heumann. Zuverlässigkeitsorientierte Bewertung bestehender Bauwerke aus Stahlbeton und Spannbeton. Dissertation, TU Braunschweig, 2014.