This article describes the details of a case study on the flexural behaviour of two UHPC I-girders, which have been tested in collaboration with the precast company Ergon, Belgium. Part I, published in CPI issue 5/2013, already described the ultra-high performance concrete (UHPC) material utilised in this research, with an average compressive strength of 150 MPa and 1% fibre volume fraction. Part II focusses on the actual manufacturing and testing of two 7 m long I-girders containing 9 prestressing strands. These girders didn’t contain – besides the steel fibres – secondary steel reinforcement, thus the UHPC carried all secondary (i.e. shear, temperature, shrinkage) tensile stresses. In the experimental phase of this study, full-scale flexural experiments were conducted on the UHPC prestressed I-girders behaviour. These experimental results were then - in the analytical phase - are compared to a prediction based on the Eurocode 2 (EN 1992-1-1) equations, which were developed and validated for normal to high strength concrete, up to a strength class of C90/105. The possibility to use this (extrapolated) Eurocode 2 to predict the flexural performance of UHPC prestressed I-girders is evaluated.
Belgian Building Research Institute – BBRI
Marnixdreef 5, 2500 Lier, Belgium