PSI - Issue 78

Vittoria Borghese et al. / Procedia Structural Integrity 78 (2026) 1229–1236

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adhesive was used for edge-, and face-gluing. Eight of the hybrid CLT panels were tested non-destructively, while two panels were tested destructively in four-point bending and planar shear (published in a separate future publication).

Table 1. Width ( w b ), thickness ( t ), density ( ρ ), average longitudinal sti ff ness ( E x ), coe ffi cient of variation ( CoV ), and number ( n ) of tested lamellae. Layer [-] Material [-] w b [mm] t [mm] ρ [kg / m 3 ] E x [MPa] CoV [%] n [-] 1 Ash (1) 95 39 680 13312 9.6 133 2 Spruce (reclaimed) 75 16 440 10646 13.0 35 (2) 3 Douglas-Fir 167 21 510 10623 11.8 47 4 Spruce (reclaimed) 70 23 440 12986 4.0 35 (3) 5 Ash (1) 95 39 680 13312 9.6 133 (1) Lamellae in layers 1 and 5 were evaluated together (2) Number tested out of a total number of 92 lamellae (3) Number tested out of a total number of 114 lamellae

Fig. 1. (a) Schematic layup of the hybrid CLT, including layer thicknesses, the total length ( L ),width ( W ), and thickness ( H ), andCLT( X , Y , Z ) and lamella coordinate systems ( x , y , z ). (b) Modal testing setup, including accelerometers locations and grid spacing. Dimensions are in millimetres.

2.3. Hybrid CLT Modal Testing

Eigenmode analysis was employed to determine the dynamic out-of-plane bending moduli in the major and minor panel directions, and the shear modulus, E X , E Y and G XY , respectively. E X , E Y , and G XY are obtained by,

48 π 2 ρ L 4 (1 − ν 500 . 6 H 2

48 π 2 ρ W 4 (1 − ν 500 . 6 H 2

π 2 ρ L 2 W 2 12 H 2

XY ν YX )

XY ν YX )

f 2

f 2

f 2

E X =

E Y =

G XY =

(1)

(2 , 0) ,

(0 , 2) ,

(1 , 1) ,

where ρ is the average density and L , W , and H are the dimensions of the CLT panel, ν XY and ν YX are the Pois son’s ratios which are 0.013 and 0.008, respectively, following Gu¨lzow (2008), and f (2 , 0) , f (0 , 2) , and f (1 , 1) are the eigenfrequencies associated to the respective mode shapes, obtained using modal analysis. Figure 1 (b) displays the experimental setup for the modal analysis. A total of 15 accelerometers ( 4514-B001 , Bru¨el & Kjær , Germany) were mounted to the hybrid CLT panels using double-sided tape. Accelerometers 1 to 6 were vertically spaced at 220 mm with an o ff set of 50 mm from the edge of the panel. Similarly, accelerometers 6 to 14 are horizontally spaced at 360 mm with an o ff set of 50 mm. This grid of accelerometers o ff ers su ffi cient detail to visualize the required eigen modes. The top-right corner of the panel was mechanically exited using an impulse hammer with a hard polymer head