Mr. S. English
David Keir Building,
Queen’s University Belfast
Shear performance of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) for bridge applications
Supervisors: Prof. Jian- Fei Chen, Dr. Desmond Robinson & Prof. Marios Soutsos
UHPFRC as the name suggests is a mix of ultra high performance concrete with a percentage, by volume, of steel or synthetic fibres, normally between 2-3%. The curing process consists of heating the material to a high temperature (90oC) at a humidity close to saturation for approximately 48 hours. The resulting material is extremely compact with remarkable mechanical and durability performances.
High strength concrete can easily achieve compressive strengths greater than 150 MPa but the failure mechanism is very brittle. In fact the failure in compression can be explosive with no evidence of a plastic domain. UHPFRC can achieve tensile strengths in the range of 8-11 MPa and above. The addition of fibres help to provide a non-brittle mechanism in bending and significantly increase the fracture toughness. UHPFRC is characterised by its psuedo-strain hardening and strain softening.
UHPFRC appears to be a promising new material not only because of its enhanced ductility but also because the mixing and casting procedures are no different to existing procedures for normal and high strength concretes. UHPFRC is, however, substantially more expensive than conventional and even High Performance Concrete. It is therefore appropriate to identify applications which fully utilize UHPFRC's mechanical properties and performance characteristics. The precast manufacturing process seems to be a promising area to develop more economical UHPFRC sections mainly due to the fact that it can have a quick turnaround period and can produce varied sections. The other aspect of precast manufacturing is the quality control and heat treatment available which is inevitably needed in the manufacturing of UHPFRC.
The aim of this research is to understand the shear performance of UHPFRC and use numerical modeling to develop applications that fully utilize the superior properties of this concrete.
Masters of Structural Engineering with Architecture (Hons) Queen’s University Belfast.
Ultra high performance concrete, shear, punching shear, fracture mechanics, FE modeling, composite materials
School of Planning Architecture and Civil Engineering
MEng in structural Engineering-Wuhan University of Technology, China
BEng in Civil Engineering-Hubei University of Technology, China
Multi-scale modelling of FRP-to-concrete bonded interfaces
This project will develop a multi-scale modelling approach to predict the interfacial bond behaviour between fiber reinforced polymer (FRP) composites and concrete. A mesomechanical model includes the explicit description of the heterogeneous material geometry close to the FRP-concrete interfacial zone will be proposed.
Damage and failure processes taking place at the mesoscale to the macroscale will be linked using a transition procedure by establishing a connection between formulations at the macroscale and mesoscale levels. This can be achieved through constructing base functions of macroscopic element numerically and then transferring mesoscale heterogeneous properties on the sub-grid to macroscale levels. This work will be chiefly numerical, using the commercial software ABAQUS.
A small number of small scale FRP-to-concrete tests will be conducted to validate the numerical models. The test will include load and strain measurements.
Prof Jian-Fei Chen, Prof Wei Sha, Prof Marios Soutsos
multi-scale modelling; fracture mechanics; finite element analysis, Abaqus