scholarly journals 4.1.4 Ultrasonic characterisation of steel fibre orientation in ultra-high performance concrete

2019 ◽  
Author(s):  
B. Ankay ◽  
K. Metje ◽  
T. Mönig ◽  
C. Zhang ◽  
T. Leutbecher
Keyword(s):  
High Performance ◽  
Steel Fibre ◽  
High Performance Concrete ◽  
Fibre Orientation ◽  
Ultra High Performance Concrete

scholarly journals Fundamental Investigations of Bond Behaviour of High-Strength Micro Steel Fibres in Ultra-High Performance Concrete under Cyclic Tensile Loading

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 120
Author(s):  
Jan-Paul Lanwer ◽  
Svenja Höper ◽  
Lena Gietz ◽  
Ursula Kowalsky ◽  
Martin Empelmann ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Fibre Orientation ◽  
High Strength ◽  
Tensile Loading ◽  
Ultra High Performance Concrete ◽  
Bond Behaviour ◽  
Pullout Tests ◽  
Transverse Pressure ◽  
Bond Zone

The objective of the contribution is to understand the fatigue bond behaviour of brass-coated high-strength micro steel fibres embedded in ultra-high performance concrete (UHPC). The study contains experimental pullout tests with variating parameters like load amplitude, fibre orientation, and fibre-embedded length. The test results show that fibres are generally pulled out of the concrete under monotonic loading and rupture partly under cyclic tensile loading. The maximum tensile stress per fibre is approximately 1176 N/mm2, which is approximately one third of the fibre tensile strength (3576 N/mm2). The load-displacement curves under monotonic loading were transformed into a bond stress-slip relationship, which includes the effect of fibre orientation. The highest bond stress occurs for an orientation of 30° by approximately 10 N/mm2. Under cyclic loading, no rupture occurs for fibres with an orientation of 90° within 100,000 load changes. Established S/N-curves of 30°- and 45°-inclined fibres do not show fatigue resistance of more than 1,000,000 load cycles for each tested load amplitude. For the simulation of fibre pullout tests with three-dimensional FEM, a model was developed that describes the local debonding between micro steel fibre and the UHPC-matrix and captures the elastic and inelastic stress-deformation behaviour of the interface using plasticity theory and a damage formulation. The model for the bond zone includes transverse pressure-independent composite mechanisms, such as adhesion and micro-interlocking and transverse pressure-induced static and sliding friction. This allows one to represent the interaction of the coupled structures with the bond zone. The progressive cracking in the contact zone and associated effects on the fibre load-bearing capacity are the decisive factors concerning the failure of the bond zone. With the developed model, it is possible to make detailed statements regarding the stress-deformation state along the fibre length. The fatigue process of the fibre-matrix bond with respect to cyclic loading is presented and analysed in the paper.

Gradient-based fibre detection method on 3D micro-CT tomographic image for defining fibre orientation bias in ultra-high-performance concrete

2020 ◽  
Vol 129 ◽  
pp. 105962 ◽  
Author(s):  
Marta Miletić ◽  
Lakshminarayanan Mohana Kumar ◽  
Ji-Youn Arns ◽  
Ankit Agarwal ◽  
Stephen J. Foster ◽  
...  
Keyword(s):  
High Performance ◽  
Detection Method ◽  
High Performance Concrete ◽  
Fibre Orientation ◽  
Tomographic Image ◽  
Micro Ct ◽  
Ultra High Performance Concrete ◽  
Gradient Based ◽  
Orientation Bias

Mesoscale study of steel fibre-reinforced ultra-high performance concrete under static and dynamic loads

2017 ◽  
Vol 116 ◽  
pp. 340-351 ◽  
Author(s):  
Yu Su ◽  
Jun Li ◽  
Chengqing Wu ◽  
Pengtao Wu ◽  
Ming Tao ◽  
...  
Keyword(s):  
High Performance ◽  
Steel Fibre ◽  
High Performance Concrete ◽  
Dynamic Loads ◽  
Ultra High Performance Concrete ◽  
Static And Dynamic Loads
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