**4. Finite Element Modelling**

slab has a 30MPa specified compression strength and a 2.6x104

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**Figure 4.** Structural model: composite floor (steel-concrete). Dimensions in (mm).

**Figure 5.** Cross section of the generic models. Dimensions in (mm).

**Profile Type Height**

**Table 3.** Geometric characteristics of the building composite floor (mm).

**(d)**

**Flange Width (bf)**

Main Beams (W610x140) 617 230 22.2 22.2 13.1 Secondary Beams (W460x60) 455 153 13.3 13.3 8.0 Columns (HP250x85) 254 260 14.4 14.4 14.4

**Top Flange Thickness (tf)**

**Bottom Flange Thickness (tf)**

**Web Thickness (tw)**

ble 3 depicted the geometric characteristics of the steel beams and columns.

MPa Young's Modulus. Ta‐

The proposed computational model, developed for the composite floor dynamic analysis, adopted the usual mesh refinement techniques present in finite element method simula‐ tions implemented in the ANSYS program [8]. The present investigation considered that both materials (steel and concrete) have an elastic behaviour. The finite element model is illustrated in Figure 7.

In this computational model, all "I" steel sections, related to beams and columns, were repre‐ sented by three-dimensional beam elements (BEAM44 [8]) with tension, compression, torsion and bending capabilities. These elements have six degrees of freedom at each node: transla‐ tions in the nodal x, y, and z directions and rotations about x, y, and z axes, see Figure 8.

On the other hand, the reinforced concrete slab was represented by shell finite elements (SHELL63 [8]). This finite element has both bending and membrane capabilities. Both inplane and normal loads are permitted. The element has six degrees of freedom at each node: translations in the nodal x, y, and z directions and rotations about the nodal x, y, and z axes, see Figure 8.

slab and the "I" steel profiles, to represent the partial interaction (steel-concrete) cases, the modelling strategy used non-linear spring elements (COMBIN39 [8]), see Figure 8, simulat‐ ing the shear connector actions. The adopted shear connector force versus displacement

An Analysis of the Beam-to-Beam Connections Effect and Steel-Concrete Interaction Degree Over the Composite

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curves were also based on experimental tests [11,12], see Figure 10.

**Figure 9.** Moment versus rotation curve: beam-to-beam semi-rigid connections [10].

**Figure 10.** Force versus slip curve: shear connectors.

**Figure 7.** Steel-concrete composite floor finite element model mesh and layout.

**Figure 8.** Finite elements used in the computational modelling.

The structural behaviour of the beam-to-beam connections (rigid, semi-rigid and flexible) present in the investigated composite floor was simulated by non-linear spring elements (COMBIN7 and COMBIN39 [8]), see Figure 8, which incorporates the geometric nonlineari‐ ty and the hysteretic behaviour effects. The moment versus rotation curve related to the adopted semi-rigid connections was based on experimental data [10], see Figure 9.

When the complete interaction between the concrete slab and steel beams was considered in the analysis, the numerical model coupled all the nodes between the beams and slab, to pre‐ vent the occurrence of any slip. On the other hand, to enable the slip between the concrete slab and the "I" steel profiles, to represent the partial interaction (steel-concrete) cases, the modelling strategy used non-linear spring elements (COMBIN39 [8]), see Figure 8, simulat‐ ing the shear connector actions. The adopted shear connector force versus displacement curves were also based on experimental tests [11,12], see Figure 10.

**Figure 9.** Moment versus rotation curve: beam-to-beam semi-rigid connections [10].

**Figure 7.** Steel-concrete composite floor finite element model mesh and layout.

290 Advances in Vibration Engineering and Structural Dynamics

**Figure 8.** Finite elements used in the computational modelling.

The structural behaviour of the beam-to-beam connections (rigid, semi-rigid and flexible) present in the investigated composite floor was simulated by non-linear spring elements (COMBIN7 and COMBIN39 [8]), see Figure 8, which incorporates the geometric nonlineari‐ ty and the hysteretic behaviour effects. The moment versus rotation curve related to the

When the complete interaction between the concrete slab and steel beams was considered in the analysis, the numerical model coupled all the nodes between the beams and slab, to pre‐ vent the occurrence of any slip. On the other hand, to enable the slip between the concrete

adopted semi-rigid connections was based on experimental data [10], see Figure 9.

**Figure 10.** Force versus slip curve: shear connectors.
