Educational Materials for Designing and Testing of Timber

Educational Materials for Designing and Testing of Timber Structures – TEMTIS Seminar Horsens / Denmark, 11 th September 2008 CROSS LAMINATED TIMBER (CLT) AND THE AUSTRIAN PRACTICE M. AUGUSTIN Institute for Timber Engineering and Wood Technology Graz University of Technology

Cross Laminated Timber – Basic idea and Product Distribution of mechanical properties in the log Utilisation of side-boards 5 -layered CLT-element 3

CLT – Production volume Arguments PRO CLT: → Massive construction, less layers in the construction, buffer for heat and moisture → High degree of prefabrication possible → Easy assembling and short duration for erection → Flexibility of utilisation Arguments CONTRA CLT: → High price Production volume: 2008 About 400. 000 m³ (+52 %) → To high amount for the market → Price will decrease (about 20 % in the next three years) Source: Timber Online / 2007 4

CLT – Examples of erected buildings “Austria-House” (2006) Turin / Italy Building Research Centre Step 2 (2007) Graz / Austria 5

CLT – Examples of erected buildings Multi-storey building (2001) Vienna / Austria “Wandritsch-Bridge” (1998) St. Lorenzen / Austria 6

R&D-Activities concern. CLT – Institute for Timber Engineering and Wood Technology / holz. bau forschungs gmb. H // TUG AREA 1_SSTC Shell and Spatial Timber Constructions (SSTC) TMC using CLT MODULE 1 MODULE 3 Mechanical Aspects Structural Analysis Verification Procedure Guidelines Building Physics Leading Details MODULE 2 MODULE 4 Connection Technique Development of Systems Architectural Potential Case Studies 7

R&D-Activities concern. CLT – Institute for Timber Engineering and Wood Technology / holz. bau forschungs gmb. H // TUG Limit states Ultimate Limit State Serviceability Limit State Topic: Creep behaviour Topics: “System effects“ “Laminating effects“ Subproject “Creep“ Subproject “Load carrying capacity“ (for elements loaded as plates and panels) Load carrying model CLT Objective Deformation factor CLT Further tests: Properties perpendicular to grain Vibration properties of CLT-floors 8

CLT in standards Eurocode 1995 -1 -1 Currently no proposals for the verification of CLT-elements → The development of an European standard is initiated by the Austrian Standardisation Organisation (ON). DIN 1052 -2004. 08 A verification procedere is given in this standard Verification of stresses on each single layer: in accord. with EN 338 D → This procedere leads to conservative results because no “homogenisation effects“ are considered ! 9

Applied to layered products: e. g. Glulam -35% æ 5 2 t ö ç ÷ × s m 23 × s m sm è 3 3 hø 15 = @ £ 1 fm, d 0, 65 × fm, d 10

Subproject “Load carrying capacity of CLT in bending“ Objective of the research work Method Results of tension tests: ft, 0, l, 05 = 12, 5 N/mm² COVt = 39, 4 % 11

Test results Mean value and COV of edge normal strength fm, c 18, 0% 45, 00 16, 0% 37, 2 35, 00 fm, c, mean [N/mm²] 39, 4 39, 0 37, 3 14, 4% 12, 5% 14, 0% 30, 00 12, 0% 25, 00 10, 0% 20, 00 7, 6% 5 # series ‚ 4 u‘ fm, g, mean = 42, 4 N/mm² COV = 9, 5 % 15, 00 10, 00 19 # series ‚ 1 u‘ 5, 00 8, 0% COV [%] 16, 1% 40, 00 6, 0% 4, 0% fm, g, mean = 44, 2 N/mm² COV = 20, 1 % 2, 0% 0, 00 1 2 3 4 5 6 Number of lamellas in the outer layers 7 8 mean value COV 12

5 % - quantile values and system factor for CLT 5% fractile and ksys of edge normal strength fm, c 34, 00 1, 30 33, 00 19 # series ‚ 1 u‘ fm, g, 05 = 29, 0 N/mm² 32, 00 32, 6 1, 25 31, 3 fm, c, 05 [N/mm²] 1, 19 29, 8 30, 00 1, 14 1, 15 29, 00 28, 00 27, 3 27, 00 1, 1 1, 09 ksys, CLT 1, 20 31, 00 1, 05 26, 00 1, 00 25, 00 1 1, 00 2 3 4 5 6 Number of lamellas in the outer layers 7 8 5% fractile system effect proposal ksys 13

Load carrying model for CLT loaded in bending Beam Model for GLT according to EN 1194: 1999 including the variation of the base material e. g. : 14

Load carrying model for CLT loaded in bending Beam Model for GLT including the variation of the base material 15

Load carrying model for CLT loaded in bending Model for CLT 16

Load carrying model for CLT loaded in bending Model for CLT 17

Load carrying model for CLT loaded in bending Load carrying model for CLT in bending - based on test results kh a ksys k. CLT/GLT (h = 110 mm, b = 110 mm) (COVt = 39, 4 %) Factor 1, 1 0, 94 1, 20 3, 15 Analy. results 29, 6 26, 9 28, 6 23, 8 12, 5 Test results 31, 3 27, 3 29, 0 - 12, 5 ft, 0, l, 05 18

Load carrying model for CLT loaded in bending Proposal of a Beam Model for CLT – Comparison with older data ft, 0, l, 05 COVt fm, c, 05, =4 test results fm, c, 05, ≥ 4 calculated [N/mm²] [%] [N/mm²] presented 12, 5 39, 4 % 31, 3 28, 1 New results 1) 26, 8 (n = 50) 30, 4 % 47, 8 45, 5 ~ 35 % 39, 1 2) 42, 9 2) 39, 4 3) 37, 5 old results (1998) 19, 3 (n = 80) 1) 5 layer CLT made of solid edge glued panels (spruce); 2) Single result of one 7 layer CLT element (width 2000 mm); 3) Single result of one 9 layer CLT element (width 2000 mm); 20

Verification in technical approvals Specifications in technical approvals 21

Comparison of verification approvals Proposal TUG DIN 1052 Comparison of verification proposals C 24 C 40 ft, 0, l, k = 14, 0 COV = 35 % ft, 0, l, k = 24, 0 COV = 25 % 15, 6 0, 65∙fm, k 26, 0 0, 65∙fm, k 29, 0 1, 21∙fm, k 38, 3 0, 96∙fm, k 22

Determination of stresses in CLT-elements loaded in bending Determination of stresses for CLT Normal stresses Shear stresses Ieff Seff 23

Determination of deformations of CLT-elements loaded in bending Determination of deformations for CLT Ratio of shear-deformation on the total deflection (single-span beam with uniformly distributed load) 50% Area of utilisation in practice beam 40% 35% Ratio w. V / wges Area of utilisation in practice plate 45% 30% 25% 20% 15% 10% isotrop spruce CLT 5 -layered 5% 0% 10 15 Ieff 20 25 Ratio S l/h eff 30 AG, eff 35 k 24

Determination of stresses in CLT-elements loaded in bending Effective second moment of area of the cross section Number of layers 3 5 7 Ieff Seff AG, eff k 25

Determination of stresses in CLT-elements loaded in bending Effective statical moment of the cross section Number of layers 3 5 7 Ieff Seff AG, eff k 26

Determination of stresses in CLT-elements loaded in bending Effective area of the cross section Number of layers 3 5 7 Ieff Seff AG, eff k 27

Determination of stresses in CLT-elements loaded in bending Shear correction factor κ for CLT cross sections with consideration of the material values in accord. to DIN 1052 6 4, 87 4, 8 4, 11 3, 88 3, 6 3, 78 3, 73 3, 70 2, 4 1, 20 1, 2 0 1 3 5 7 9 11 13 Number of layers n Ieff Seff AG, eff k 28

Determination of stresses in CLT-elements loaded in bending Shear correction factor with values from standards Material properties EN 338 (all strengthclasses) 1) C 24 C 30 (in accord. with the approvals) 2) G 9090 = G 090/10 G 9090 = 50 [N/mm 2] 3 -layered 4, 9 6, 5 7, 0 5 -layered 4, 1 5, 4 5, 9 7 -layered 3, 9 5, 1 5, 5 1) E 0/E 90 = 30; E 0/G 090 = 16; G 090/G 9090 = 10 2) Für C 24: E 0/E 90 = 30; E 0/G 090 = 16 Für C 30: E 0/E 90 = 30; E 0/G 090 = 16 Ieff Seff AG, eff k 32

Determination of stresses in CLT-elements loaded as panel CLT wall elements under homogeneous shear (shear stiffness) experimental and theoretical solution (doctoral thesis in process: Th. Moosbrugger) - without openings u/a=0. 067 ≈ 0. 29 u a board spacing: u = 5 mm u/a= 0. 067 board width: a = 75 mm Gplate, mean= 229 N/mm² (5 tests, COV = 0. 16) practical range 60 mm 229 / 750 0. 3 0. 8 - with openings 33

Creep behaviour of CLT-elements Specimens with two cross sections: GLT and CLT Results Climate Test setup: 4 – point – bending test according to EN 408 Climate 2 Climate 1 Stress GLT CLT level Sl. 2 high + 38, 5 % Sl. 1 - low + 46, 5 % Sl. 2 high + 19, 3 % Sl. 1 - low +41, 9 % Proposals for standardisation kdef, CLT, 5 -layer Futher details tests: Tests with two climates (55%/20°C; 78%/20°C) and two stress levels (about 3 N/mm² and 8 N/mm²) SC 1 0, 85 SC 2 1, 10 Approximatly values for Plywood 34

Compression perpendicular to grain of CLT-cubic specimens Stiffness Ec, 90, mean = 500 N/mm² Strength fc, 90, k = 3, 0 N/mm² Test setup: Tests on specimens with different number of layers, position of the board in the log, built-up factor and loading situations 35

Contact DI Manfred AUGUSTIN Scientific Assistent +43 (0) 316 873 -4604 manfred. augustin@lignum. tugraz. at Inffeldgasse 24, A-8010 Graz / Austria THANKS FOR YOUR ATTENTION !