# Large-Scale Experimental Static Testing on 50-Year-Old Prestressed Concrete Bridge Girders
## 6 Conclusions  
In this paper, the first results of the large-scale experimental tests of the BRIDGE 150 research project were reported. This research project proposes an extensive experimental study for the assessment of the performance of existing PC bridges. A detailed description of the design and execution of the experimental program was reported, including load test scheme and sensor devices' layout. The results of the first group of four PC girders are presented and discussed. Based on the results of the flexural tests conducted with a three-point bending test scheme on a large facility for real-scale mechanical experiments, the influence of the material and structural characteristics of the girders was highlighted. In particular, a brittle behavior was detected, with the failure firstly located at the most compressed zone subjected to bending, highlighting the cast in situ slab as a weak structural component. An overestimation of the concrete strength assumptions was found within the design documentation for both the PC beam and cast in situ slab. Comparing these values with the outcomes provided by the destructive laboratory tests, a reduction of about 46% and 33% was recorded for the cast in situ slab and PC beam, respectively. Additional activities will be conducted to increase data on the mechanical properties of concrete and steel with destructive tests in addition to specific research aimed at estimating the effective prestress force with concrete relief test and strand cutting procedures on the tested girders. Given the healthy structural condition of this first group of PC beams, a uniform ultimate capacity was found among them, without any dependence on particular deterioration mechanisms.  
The results collected from this experimental study could be of extreme interest to evaluate the specimen characteristics and calibrate numerical models for the safety assessment of existing structures. Moreover, a proper numerical model fitting the results, according to the outcome of the dynamic tests, will be representative of the in-service health condition of the C.so Grosseto viaduct. The next large-scale tests will analyze different shear span lengths to study the bending moment interaction resistance mechanism in addition to the shear failure mechanism for undamaged and damaged girders. Furthermore, specific mechanical tests for pier caps available for the BRIDGE 150 research project will be also planned and performed.  
Conceptualization, F.T., D.S., A.Q., F.B., G.R. and B.C.; methodology, F.T., D.S., A.Q. and F.B.; investigation, P.S., F.T., D.S., A.Q. and M.A.; resources, P.S., F.T., D.S., A.Q. and F.B.; data curation, P.S. and A.Q.; writing--original draft preparation, P.S., D.S. and A.Q.; writing--review and editing, F.T., F.B., M.A. and B.C.; supervision, F.T.; project administration, F.T. and F.B.; funding acquisition, F.T., D.S. and B.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. This research received no external funding. Not applicable. Not applicable.  
Data Availability Statement: Not applicable.  
**Acknowledgments: BRIDGE I 50 is a research project based on a research agreement among universities, public authorities and private companies. Members of the Management Committee: S.C.R. Piemonte (President), Politecnico di Milano (Scientific Coordinator), Politecnico di Torino (Scientific Responsible of the Experimental Activities), Lombardi Engineering (Secretary), Piedmont Region, City of Turin, Metropolitan City of Turin, TNE Torino Nuova Economia, ATI Itinera & C.M.B., ATI Despe & Perino Piero, Quaranta Group. BRIDGE I50 website: [[http://www.bridge50.org](http://www.bridge50.org)]([http://www.bridge50.org](http://www.bridge50.org)).  
**Conflicts of Interest:** The authors declare no conflict of interest.