THE EUROPEAN PROJECT SUREBRIDGE
ANALYSIS OF LABORATORY TEST BEAMS

Paolo S. Valvo(1), Erika Davini(1), Fabio Ricci(2)
(1) Department of Civil and Industrial Engineering, University of Pisa
Largo Lucio Lazzarino, 56122 Pisa, Italy
e-mail: p.valvo@ing.unipi.it

(2) A.I.C.E. Consulting S.r.l.
Via G. Boccaccio, 20, 56017 San Giuliano Terme (Pisa), Italy
e-mail: f.ricci@aiceconsulting.it

Abstract

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).

The effectiveness of the proposed technique has been evaluated through laboratory tests on 6-m long beams subjected to four-point bending at Chalmers University of Technology, Gothenburg, Sweden (Figure 1): for comparison, a reference un-strengthened concrete beam (Figure 2a) and a concrete beam strengthened with the SUREBridge technique (Figure 2b) have been tested.



Figure 1: Laboratory test on a beam strengthened with the SUREBridge technique

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 4: Non-linear stress-strain curves for (a) concrete and (b) steel


 

Figure 5: Non-linear analysis of the un-strengthened beam


 

Figure 6: Non-linear analysis of the strengthened beam




Figure 7: Theoretical load-deflection curve for the un-strengthened beam




Figure 8: Theoretical load-deflection curve for the strengthened beam




Figure 9: Theoretical vs experimental load-deflection curves for the un-strengthened beam




Figure 10: Theoretical vs experimental load-deflection curves for the strengthened beam




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