PSI - Issue 64

Carmine Lima et al. / Procedia Structural Integrity 64 (2024) 849–856 Lima et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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- Medium/High concrete strength: concrete strength class C60/75 (EN 1992-1-1, 2004) produced with a specific binder commercialized with the label of Structure Flow SCC (General Admixtures, 2022) mixed with water, gravel and natural sand (nominal diameter ranging between 0 mm and 8 mm) and characterized by an average cubic compressive strength (EN 12390-3, 2019) equal to 77.88 MPa and average flexural strength (EN 12390-5, 2019) equal to 3.86 MPa; - UHP-FRC concrete: made of Composite M130 (General Admixtures, 2021), a premixed UHP-FRC mixture produced by mixing binder (component A), liquid activator (component B) and fibers (component C) an average cubic compressive strength (EN 12390-3, 2019) equal to 101.06 MPa and average flexural strength (EN 12390 5, 2019) equal to 6.95 MPa; 2.2. Push-out samples preparation The push-out test protocol was inspired by the “standard push - out test” defined by EN 1994-1-1 (2004) and schematized in the following Fig. 1.

Fig. 1 Standard push-out test setup

The experimental campaign was conceived for obtaining three nominally identical samples for three different steel concrete assemblies characterized by the following properties of the concrete slabs: - 3 samples of C25/30, with slab thickness s = 150 mm made of “ ordinary ” structural class C25/30 concrete; - 3 samples of C60/75 with slab thickness s = 120 mm made of “medium /high ” structural class C60/75 concrete; - 3 samples of UHP-FRC with slab thickness s = 75 mm made of UHP-FRC concrete mixtures. Steel profiles HEB260 type S275JR and Nelson connectors steel type S235JR+C450, characterized by a nominal diameter equal 16 mm and nominal length of 64 mm (in order to guarantee a length-to-diameter ratio equal to 4), were used for the nine produced samples. Steel reinforcement according to EN 1991-1-1 (2004) (10 mm steel bars type B450C) was adopted for both C25/30 and C60/75 samples meanwhile, due to the reduced section and high tensile strength of the UHP-FRC samples were produced without the steel reinforcement (see also Fig. 2).

C25/30 samples

C60/75 samples

UHP-FRC samples

Reinforcement: 10 mm steel bars Reinforcement: 10 mm steel bars

without reinforcement Fig. 2 Representative cross-section of the produced push-out steel-concrete samples

For each sample the following procedure was adopted for realizing the steel-concrete elements (Fig. 3): (i) four connectors were welded on each flange of the steel beam (Fig. 3a) and (ii) steel reinforcement defined in Fig. 2 was