Effect of construction features on the dynamic performance of mid-rise CLT platform-type buildings

Figures & data

Figure 1. Reference building at NMBU.

Figure 2. Typical layout of shear walls in reference building.

Table 1. Specifications of shear walls and connectors.

Shear-wall type	Floor	*AB-type	**HD-type	Shear-wall type	Floor	AB-type	HD-type
1	1–4	AB-7	HD-3	4	1–3	AB-5	HD-1
	5–6	AB-6	HD-2		4–7	AB-1	HD-1
	7–8	AB-6	HD-1		8	AB-1	–
	9	AB-2	HD-1		9	–	–
2	1–8	–	HD-1
	9	–	–	5 and 6	1–2	AB-5	HD-2
3	1–5	AB-9	HD-3		3–4	AB-4	HD-2
	6	AB-9	HD-2		5–6	AB-4	HD-1
	7–8	AB-8	HD-1		7–8	AB-1	HD-1
	9	AB-3	HD-1		9	–	–

*AB symbolizes angle bracket.

**HD symbolizes hold-down.

Table 2. Description of Python scripts.

Script #	Description
1	A script for sensitivity analysis and model updating. The script works for predefined element groups and materials named in the script. The algorithm steps are sensitivity analyses for defined parameters, exclusion of the insensitive parameters, model updating, and plotting results
2	A script making original models ready for the implementation of link elements. The algorithm applies updated materials and pre-created link elements
3	A script for creating Geo-1, Geo-2 and Geo-3 then runs various eccentricities. The algorithm creates and saves new models for each eccentricity variation, and creates new models using updated material, and stores results for each variation

Figure 3. Baseline FE superstructure model.

Figure 4. Normalized sensitivity values of material properties.

Table 3. Reference (seed) properties for CLT elements*.

CLT-Panel layup (mm)	E1 (GPa)	E2 (GPa)	E3 (GPa)	G1 (GPa)	G2 (GPa)	G3 (GPa)
CLT 90 3S (30–30–30)	7.46	3.91	0.30	0.37	0.04	0.04
CLT 100 5S (20–20–20–20–20)	6.75	4.62	0.30	0.34	0.03	0.03
CLT 120 5S (30–20–20–20–30)	7.46	3.91	0.30	0.37	0.04	0.04
CLT 130 5S (30–20–30–20–30)	7.73	3.64	0.30	0.39	0.04	0.04
CLT 140 5S (40–20–20–20–40)	7.96	3.41	0.30	0.40	0.04	0.04
CLT 160 5S (40–20–40–20–40)	8.34	3.03	0.30	0.42	0.04	0.04
CLT 180 5S (40–30–40–30–40)	7.46	3.91	0.30	0.37	0.04	0.04
CLT 200 5S (40–40–40–40–40)	6.75	4.62	0.30	0.34	0.03	0.03

*Parallel to face laminations (direction-1); perpendicular to face laminations (direction-2); direction-3 is perpendicular to plate.

Table 4. Seed values for loads and material density.

Parameter	Symbol	Units	Value
Superimposed dead load on internal floors	SDLi	kN/m^2	2.10
*Live load on internal floors	LLi	kN/m^2	0.48
*Live load on roof	LLr	kN/m^2	0.17
Density of CLT	ρ	kg/m^3	450

*Recommended by European Committee for Standardization (2004a).

Table 5. Initial and updated parameter values with an absolute change greater than 1.0% during sensitivity analyses.

Parameter	Units	Initial value	Updated value	% Change
*CLT-100 G1,d	GPa	0.261	0.051	80.5
CLT-130 G1,d	GPa	0.300	0.058	80.7
CLT-160 G1,d	GPa	0.320	0.063	80.3
CLT-160 G1	GPa	0.420	0.209	50.2
CLT-100 G1	GPa	0.340	0.503	47.9
**CLT-100 G1,v	GPa	0.255	0.181	29.0
CLT-140 G1	GPa	0.400	0.494	23.5
CLT-180 G1	GPa	0.370	0.455	23.0
CLT-90 G1	GPa	0.370	0.342	7.60
CLT-120 G1	GPa	0.370	0.400	8.10
CLT-120 G1,v	GPa	0.280	0.308	10.0
CLT-200 G1	GPa	0.340	0.354	4.10

*CLT wall with door opening.

**CLT wall with window opening.

Figure 5. Convergence of the cost function during model updating.

Figure 6. FE model versus experimental mode shapes.

Table 6. FE models versus experimental natural frequencies.

Mode	Natural frequencies (Hz)			% Var	Initial MAC	Updated MAC
	Initial FE (fa,i)	Updated FE (fa,u)	Experimental (fe,i)	${\displaystyle \frac{f_{a,u}-f_e}{f_e}}$
1	1.988	1.917	1.913	0.209	1.000	1.000
2	3.139	2.455	2.414	1.698	0.999	0.998
3	2.744	2.697	2.693	0.149	1.000	1.000

Figure 7. Schematic of wall-to-floor link objects.

Table 7. Stiffness of angle bracket and hold-down anchors in FE analyses.

Type of hold-down	Number of brackets	Tensile stiffness (kN/mm)
HD-1	1	2.65
HD-2	2	5.30
HD-3	3	7.95
HD-4	4	10.6
HD-5	5	13.3

Table 8. Overview of the types of angle brackets employed in the FE analyses.

Connector type	Number of nails	Tensile stiffness (KN/mm)	Shear stiffness (KN/mm)	Illustration
AB-1	5	1.86	0.69
AB-2	8	2.98	1.10
AB-3	12	4.47	1.65
AB-4	13	4.85	1.79
AB-5	18	6.71	2.48
AB-6	25	9.31	3.44
AB-7	35	13.04	4.81
AB-8	36	13.41	4.95
AB-9	36×2	26.82	9.90

Figure 8. Normalised sensitivity values for connector parameters.

Figure 9. Variations in building footprint.

Table 9. Effects of variations of plan geometry on natural frequencies and mode types.

Mode order	Natural frequencies (Hz)				Mode shape
	*Geo-0	Geo-1	Geo-2	Geo-3	**UX	UY	RZ
1	1.92	2.40	2.26	2.35		✓
2	2.45	2.45	2.54	2.40	✓
3	2.70	3.04	2.93	3.09			✓
4	6.25	7.02	6.81	6.94		✓
5	6.94	7.27	7.31	7.07	✓
Eccentricity (m)	ex = ey = 0	ex = ey = 4.4	ex = ey = 4.2	ex = ey = 2.9

*Geo-0 is the reference (updated FE model) building model, Geo-1, -2 and -3 represents building models with footprint variations.

**UX-sway mode along X-axis, UY-sway mode along Y-axis and RZ – torsional about Z-axis.

Table 10. Number of modes contributing to 90% mass participation.

	Geo-0		Geo-1		Geo-2		Geo-3
	x-dir	y-dir	x-dir	y-dir	x-dir	y-dir	x-dir	y-dir
Number of modes	53	55	39	38	39	38	36	33

Figure 10. Variations in eccentricity versus corresponding masses and natural frequencies, respectively.

European Committee for Standardization (2004a) (2004) EN 1991-1-1 (English): Eurocode 1: Actions on Structures – Part 1-1: General Actions – Densities, Self-Weight, Imposed Loads for Buildings (The European Union).

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