The European research project SUREBridge (Sustainable Refurbishment of Existing Bridges) is developing a new concept for the structural strengthening of road bridges. According to the proposed technique, glass fibre-reinforced polymer (GFRP) sandwich panels are installed on top of the existing concrete slab and pre-stressed carbon fibre-reinforced polymer (CFRP) laminates are adhesively bonded to the bottom surfaces of the longitudinal girders (www.surebridge.eu).
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Finite element models of the laboratory test beams were developed by using the commercial software Straus7®. A fibre-element modelling approach – frequently used in push-over seismic analyses – was adopted since it represents a good compromise between ease of implementation and accuracy of results in material non-linear analyses. Figure 3 shows the cross sections of the un-strengthened and strengthened beams. Specific non-linear stress-strain curves were used for the different parts of the cross sections: unconfined concrete, confined concrete and steel rebars (Figure 4). The GFRP sandwich panels were modelled as LAMINATE elements; CONNECTION elements were used to model the epoxy bonding between the CFRP laminate and the concrete beam. In addition, the plane-section constraint was enforced through RIGID LINKS. Non-linear static analyses were carried out (Figure 5 and Figure 6) and the theoretical load-deflection curves were obtained (Figure 7 and Figure 8) and compared to the experimental results (Figure 9 and Figure 10). |
Figure 2: Cross sections of the (a) un-strengthened and (b) strengthened beam
Figure 3: Finite element model of the (a) un-strengthened and (b) strengthened beams
Figure 5: Non-linear analysis of the un-strengthened beam
Figure 6: Non-linear analysis of the strengthened beam
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