Jan-Paul Lanwer

Jan-Paul Lanwer, M.Sc.

Institute of Building Materials, Concrete Construction and Fire Safety

Division of Concrete Construction

Beethovenstraße 52

38106 Braunschweig

Telephone: 0531/391-5412

Research project:

Damage processes in ultra-high performance fibre-reinforced concrete under cyclic tensile loading – experimental und theoretical investigations

The main goal of this research project is to capture, to describe and to model the degradation behavior of ultra-high performance fiber-reinforced concrete under cyclic tensile loading considering the damage evolutions and mechanisms on the micro- and mesoscale.

Currently ultra-high performance fiber-reinforced concrete (UHPFRC) usually comprise a high content of fibers to avoid brittle failure. The high content of fibers leads to an overcritical tensile load-bearing behavior and a high post-cracking tensile strength. The post cracking tensile strength has a great influence on the load-bearing capacity and the deformation behavior of UHPFRC-structures under bending, shear and torsion. Because of the higher compressive and tensile strength, compared to normal strength concrete, UHPFRC is usually used for slim and thin-walled as well as weight- and performance-optimized structures. Due to this weight reduction and higher slenderness, UHPFRC-structures are vulnerable to cyclic loading. The effect of fibers in ultra-high performance concrete exposed to cyclic loading is not quite clarified. Additionally, the degradation behavior of UHPFRC under cyclic loading has not been sufficiently investigated and understood yet.

For this reason, the degradation processes and mechanisms will be investigated experimentally and numerically under cyclic tensile loading within this research project. On the one hand, experimental investigation on small-sized specimens, e.g. fiber tensile tests, fiber pull-out tests and UHPFRC-tensile tests will be carried out. The experiments should be analyzed and documented by imaging techniques like digital microscopy, x-ray scans, scanning electron microscopy and photogrammetric measurement system. On the other hand, the stress-strain behavior will be analyzed mathematically and numerically on the mesoscale. Continuum mechanical models including inelastic deformation behavior and damage will be extended to describe the material behavior of the single components under cyclic tensile loading. The bond behavior between fiber and concrete matrix will be integrated discretely into an advanced bond model in finite element analysis.

Publications within the framework of the RTG:

Publications in peer-reviewed scientific journals/book chapter:

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

Lanwer, J.-P.; Oettel, V.; Empelmann, M.; Höper, S.; Kowalsky, U.; Dinkler, D.: Bond behavior of micro steel fibers embedded in ultra-high performance concrete subjected to monotonic and cyclic loading. In: Structural Concrete 20 (2019), Heft 4, S. 1243-1253.