PSI - Issue 78

Adriano Andrés Del Fiol et al. / Procedia Structural Integrity 78 (2026) 1713–1720

1716

tangential penalty friction (μ = 0.4) was defined along the panel-to-frame interface. A finite sliding formulation with node-to-surface discretization was used, and the contact was slightly smoothed (0,2). The contacts were adjusted to eliminate overclosures, and no initial gaps or bonding effects were introduced. Frictional behaviour may be refined in further analyses. The panel dimensions were 4200 × 2750 × 135 mm. The mesh size of the infill panel was approximately 50 mm. Material properties for the masonry were defined using the CDP model (Table 1), calibrated from the experimental data reported by Calvi and Bolognini (2001). The material response considered the masonry properties for horizontal holes positioning.

Table 1. concrete and masonry CDP parameters.

Characteristics

Concrete

Masonry 1432 MPa

Young’s Modulus Poisson’s ratio Dilatation angle

E n ψ

31146.9 MPa

0.2 35° 0.1

0.2 30° 0.1

Eccentricity

ϵ

f bo /f co

1.16

1.16

Ratio

K parameter

K

0.667

0.667 0.001

Viscosity parameter Compressive strength

μ

0.007985 25 MPa 0.00320 2.49 MPa 0.00076

fc

1.10 MPa

0.0012

Ultimate compressive inelastic strain

ε cu

Tensile strength

ft

0.15 MPa

0.0006

Ultimate tensile crackin strain

ε cku

3.1.3. CLT Infill Panel The CLT infill panel was modeled as a continuous, five-layer cross-laminated timber wall with a total thickness of 85 mm. A lateral gap of 50 mm was introduced on each vertical side to replicate realistic construction tolerances, allowing the panel to deform independently from the surrounding RC frame and to activate both frictional and mechanical interaction through its connections ( Fig. 3 b). The panel was characterized by orthotropic elastic properties, defined according to the predominant in-plane orientation of the laminar layers. The material orientation was assigned to reflect the anisotropic nature of CLT, ensuring appropriate stiffness distribution along the strong and weak axes. The panel-to-frame connection was represented using steel T-shaped plates anchored to both the concrete frame and the timber panel ( Fig. 3 c). In the numerical model, the interaction between the steel plates and both substrates (RC and timber) were initially idealized via tie constraints. In detail, the connection was modeled as a double-shear system, in which the steel plate was centrally embedded within the timber panel. This operation required a two-step interaction definition: (a) the CLT panel was connected to the steel plate through distributed coupling constraints on both sides; (b) the steel plate was in turn connected to the RC frame using tie constraints at the top and bottom. This approach ensured full bonding, representing the effect of bolted joints. It is worth noting that a plastic or damaged model was not implemented for the CLT panel because it was assumed that the panel always behaved elastically. To model the connections, steel plates of S275J steel type were employed, by using an isotropic elastoplastic material, which was assumed to remain ductile under cyclic loading conditions, without damage or fracture modelling in the present study. In order to simulate the load transfer across the panel-plate assembly, an elastic connector was inserted between the two coupled regions of the CLT and the steel plate. This connector was defined using the Cartesian elastic behavior option, with stiffness values of !! =103,95 × 10 6 N/m and "" = ## =10,43 × 10 6 N/m. These values reflect the directional stiffness of the mechanical connections and account for possible local flexibility. The connector was