PSI - Issue 62

A. Lupoi et al. / Procedia Structural Integrity 62 (2024) 963–971 A. Lupoi, F. Romano / Structural Integrity Procedia 00 (2024) 000–000

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3. Experimental test

The experimental test consists of a three-point bending test, where the concentrated load is applied at the girder mid-span. The test was performed by Eucentre Foundation (European Centre for Training and Research in Earthquake Engineering) at the DICAr laboratory of the University of Pavia, Italy.

3.1. Experimental test setup

Fig. 4 shows the location of the girder supports and the load application system. In particular, the girder was simply supported by a pin and a roller at the two girder ends; the supports were positioned 35 cm from the ends, hence the support distance is 31.9 m. The sample was superiorly constrained by a steel reaction system consisting of two "A" frames 4.5 m in height, composed of box sections beam elements welded together and subsequently assembled. The reaction system supports the top transverse beam for the distribution of load provided by two hydraulic actuators, in addition to contrast the eventual girder out-of-plane instability. The top transverse beam is connected to the laboratory concrete ground floor by means of two post-tensioned Dywidag type 40 WR bars, in order to contrast the force applied by the two actuators. The latter, installed at mid-span of the transverse beam by using M39 threaded bars, provide a maximum load of 1064 kN in compression and 720 kN in tension, considering a pressure of 280 bar. The steel reaction system was positioned at the girder mid-span, and the two “A” frames connected to the laboratory ground floor using four post-tensioned Dywidag type 40 WR bars.

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Fig. 4. (a-b) Location of the reaction system; (c) contrast to out-of-plane instability; (d) load application system (EUCENTRE, 2023).

Linear displacement transducers were installed on the sample, for a total of 46 instruments:

• 12 on the intrados to reconstruct the deformation;

• 24 on the web, divided into 4 square grids of 6 instruments, to obtain the local web deformations close to the load application point;