CLT Adhesive Tests in Support of Mass Timber Buildings

Transcription

1 CLT Adhesive Tests in Support of Mass Timber Buildings DES604 Jason Smart, P.E. Manager, Engineering Technology American Wood Council Sam Francis, C.B.O. Senior Director, National Programs American Wood Council

2 The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider # Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. Participants may download the presentation here: resources This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation. 2

3 COURSE DESCRIPTION Adhesive bonding of wood laminations allows for the manufacture of large wood members. Adhesives used for this purpose must meet specified levels of resistance to heat at elevated temperatures. This performance is determined through testing. Code-referenced standards currently require such adhesives to pass a bond line shear test at elevated temperatures as a demonstration of this performance. The presentation will include an overview of the manufacturing of glued engineered wood products and the applicable code-referenced standards. During the work of the ICC Tall Wood Building Ad Hoc Committee (TWB), special test programs were developed and performed with the input of the fire service. New test protocols were developed to ensure the adhesive used in crosslaminated timber (CLT) will not result in the re-kindling of uncharred wood at the bond line. Background and the resulting test protocol for CLT will be presented. 3

4 LEARNING OBJECTIVES Upon completion, participants will be: What is CLT? 1 3 Recognize how cross-laminated timber and other glued engineered wood products are manufactured. 2 Compartment Tests 4 Describe the compartment fire test results and circumstances that led to the development of a full-scale room fire protocol for qualifying adhesives used to manufacture cross-laminated timber. Adhesive Qualification Tests Summarize the test protocols and associated pass/fail criteria established in PRG 320 for qualifying adhesives and evaluate their impact on mass timber construction. Applicable Code Requirements Understand the proposed code change that addresses the performance requirements for cross laminated timber, and state its impact on mass timber construction. 4

5 POLLING QUESTION 1. What is your profession? a) Architect b) Engineer c) Building Code Official d) Fire Code Official e) Other 5

6 Outline What is CLT? Compartment Tests Adhesive Qualification Tests Applicable Code Requirements 6

7 CONCEPT OF CROSS -LAMINATED TIMBER Photos provided by FPInnovations 7

8 CONCEPT OF CROSS -LAMINATED TIMBER CROSS LAMINATED TIMBER PANELS Photo provided by FPInnovations 8

9 MASS TIMBER CONCEPT - HISTORY OF CLT st CLT patent - France st CLT projects - Switzerland and Germany Improved press technology st multi-story res building - Austria Early 2000 s CLT use (Europe) increased significantly Green building movement driven Better efficiencies, product approvals, improved marketing and distribution channels Over 500 CLT buildings in England Recent - US and Canadian use of CLT 9

10 CLT VS GLT Cross Laminated Timber Glued Laminated Timber Thick Orthotropic Plate Beam-like member Graphics provided by WoodWorks Graphics provided by APA 10

11 CROSS-LAMINATED TIMBER Components of CLT A lamination consists of a piece of sawn lumber or SCL Layer: An arrangement of laminations of the same thickness, grade, and species combination laid out essentially parallel to each other in one plane CLT consists of at least 3 orthogonal layers, laminated with structural adhesives Graphics provided by WoodWorks 11

12 POLLING QUESTION 2. Which of the following is true regarding CLT? a.all laminations within a single layer are parallel b.alternating layers are perpendicular c. There is a major and minor axis d. All of the above 12

13 Outline What is CLT? Compartment Tests Adhesive Qualification Tests Applicable Code Requirements 13

14 COMPARTMENT TESTS What is a Compartment Fire Test? A fire test within a compartment having at least one opening Simulates a flashover fire in an actual room or apartment Fuel type: Either real furnishings, gas or other combustible fuels 14

15 FIRE TESTING: COMPARTMENT TEST VS. ASTM E119 Compartment Fires: Temperatures typically peak more quickly and remain higher than E119 standard fire test during fully-developed phase Temps start to decrease once fuel is mostly consumed (decay phase) E119 Standard Fire: Temperatures gradually increase throughout exposure It takes >4 hours for the temperature to reach the same level as the typical peak temp in a compartment fire 15

16 NFPA FPRF COMPARTMENT TESTS NFPA Fire Protection Research Foundation (FPRF) Tests done for NFPA s Property Insurance Research Group (PIRG) Purpose: Evaluate the contribution of CLT elements to compartment fires to collect data for insurance modeling Tests performed by NRC Canada Tests performed at NIST facilities 6 Compartment tests: 2 with all CLT protected 4 with various surfaces exposed Report available at FPRF website: 16

17 NFPA FPRF COMPARTMENT TESTS No significant contribution of CLT when all surfaces were protected with Type X gypsum wallboard Where surfaces were exposed, CLT contribution increased with increasing exposed CLT surface area Modeling performed by Research Institute of Sweden (RISE) was close to measured results 17

18 NFPA FPRF COMPARTMENT TESTS Fire re-growth observed in multiple FPRF tests Fire re-growth caused by failure of bond lines before being reached by char front (i.e., heat-delamination) Images courtesy of Joseph Su, NRC Canada 18

19 NFPA FPRF COMPARTMENT TESTS Test 1-4: Exposed CLT ceiling 1 st heat-delamination occurred around 50 minutes, extending fullydeveloped phase 2 nd heat-delamination occurred around 150 minutes, resulting in fire re-growth Graphs courtesy of Joseph Su, NRC Canada 19

20 NFPA FPRF COMPARTMENT TESTS 20

21 NFPA FPRF COMPARTMENT TESTS Similar fire re-growth behavior observed in other compartment tests with exposed areas of CLT All instances of fire re-growth were caused by adhesive heat delamination Result of this behavior Fire may not necessarily burn out after compartment contents are consumed 21

22 POLLING QUESTION 3. In the FPRF compartment tests, all instances of fire regrowth were caused by adhesive heat delamination. True False 22

23 Outline What is CLT? Compartment Tests Adhesive Qualification Tests Applicable Code Requirements 23

24 ADHESIVE QUALIFICATION TESTS Position of ICC-TWB Ad-Hoc Committee Heat delamination leading to fire re-growth deemed unacceptable for Tall Mass Timber buildings Members should perform more like solid wood Steady, predictable char development Unheated core insulated by char layer No fire re-growth 24

25 ADHESIVE QUALIFICATION TESTS Direction provided by ICC-TWB Ad-Hoc Committee Need test protocol capable of identifying heat-delaminating adhesives Code-referenced standards governing CLT should require adhesive qualification using this protocol 25

26 ADHESIVE QUALIFICATION TESTS Test protocol developed by Southwest Research Institute (SwRI) Large-scale compartment test (9 x 19 compartment) Exposed CLT ceiling (as was tested in FPRF Test 1-4) Same CLT span as in FPRF tests (~15 ) Same loading as in FPRF tests (20 psf) Same ventilation ratio as in FPRF tests (~0.03 m 0.5 ) 26

27 ADHESIVE QUALIFICATION TESTS Large-scale Compartment Test Protocol Calibration of adhesive qualification test protocol Exposure replicates conditions of FPRF baseline test (FPRF Test 1-1) Exposure based on heat flux to the ceiling to replicate fire curve of FPRF Test 1-1 (no exposed CLT) FPRF Test 1-1 Adhesive qualification calibration test 27

28 ADHESIVE QUALIFICATION TESTS Large-scale Compartment Test Protocol Validation of adhesive qualification test protocol Validation test performed on same CLT used in FPRF tests to verify similar performance Prior to flashover (11 minutes) Flashover (~14 minutes) 28

29 ADHESIVE QUALIFICATION TESTS Large-scale Compartment Test Protocol Validation of adhesive qualification test protocol Validation test performed on same CLT used in FPRF tests to verify similar performance Fully-developed phase (15 minutes) Fully-developed phase (40 minutes) 29

30 ADHESIVE QUALIFICATION TESTS Large-scale Compartment Test Protocol Validation of adhesive qualification test protocol Validation test performed on same CLT used in FPRF tests to verify similar performance Just prior to fire re-growth (2:59) 2 nd Flashover caused by fire re-growth (3:10) 30

31 ADHESIVE QUALIFICATION TESTS 31

32 ADHESIVE QUALIFICATION TESTS FPRF Test 1-1 Adhesive qualification calibration test FPRF Test 1-4 Adhesive qualification validation test 32

33 ADHESIVE QUALIFICATION TESTS Validation of adhesive qualification test protocol Comparison of temperatures at ceiling ~450 C during decay phase, before fire re-growth 800 C at end of test, due to fire re-growth FPRF Test 1-4 Adhesive qualification validation test 33

34 ADHESIVE QUALIFICATION TESTS Qualification tests performed on other adhesives Fire re-growth observed with PUR No fire re-growth observed with Melamine formaldehyde resin Improved PUR Test identifies acceptable performance Heat-delaminating PUR Melamine formaldehyde resin Improved PUR 34

35 ADHESIVE QUALIFICATION TESTS Small-scale Adhesive Qualification Test Protocol (CSA O177 Sect. A.2) As modified by PRG-320: Crosssection of CLT exposed to flame Flame temperature: F ( C) Exposure duration: 10 minutes (5 minutes on each side) Image courtesy of FPInnovations 35

36 ADHESIVE QUALIFICATION TESTS Small-scale Adhesive Qualification Test Protocol (CSA O177 Section A.2) CLT samples cut and inspected for delamination following test Distinguishes between adhesives that undergo heat-delamination vs. those that do not Images courtesy of FPInnovations 36

37 POLLING QUESTION 4. Large-scale compartment tests performed at SwRI revealed: a. Fire re-growth was observed with tested heat-delaminating PUR b. No fire re-growth was observed with tested melamine formaldehyde resin c. No fire re-growth was observed with tested improved PUR d. All of the above 37

38 Outline What is CLT? Compartment Tests Adhesive Qualification Tests Applicable Code Requirements 38

39 APPLICABLE CODE REQUIREMENTS International Building Code (IBC) IBC Chapter 23 requires CLT to be manufactured and identified in accordance with ANSI/APA PRG

40 APPLICABLE CODE REQUIREMENTS PRG 320 Standard for Performance-Rated CLT Contains a wide range of requirements for CLT, including Dimensions and tolerances Component requirements (laminations, adhesive, etc.) Performance criteria Qualification and marking Quality assurance 40

41 APPLICABLE CODE REQUIREMENTS PRG Standard for Performance-Rated CLT Adhesives must meet the requirements of ANSI 405 (which references CSA O177 Section A.2) - AND - Adhesives must comply with the requirements for elevated temperature performance per Annex B (large-scale compartment test) 41

42 APPLICABLE CODE REQUIREMENTS Annex B of PRG Large-scale Compartment Test 42

43 APPLICABLE CODE REQUIREMENTS Annex B of PRG Calibration performed on protected CLT (same as FPRF Test 1-1) 43

44 APPLICABLE CODE REQUIREMENTS Annex B of PRG Qualification Test Method 8 x 16 CLT specimen exposed CLT ceiling Specimen subjected to prescribed exposure Test performed for a period of 240 minutes (4 hours) 44

45 APPLICABLE CODE REQUIREMENTS Annex B of PRG Acceptance Criteria CLT assembly must sustain applied load throughout entire 240-minute test Temperatures shall not exceed 950 F (510 C) during decay phase This identifies and excludes adhesives that allow delamination leading to fire re-growth 45

46 POLLING QUESTION 5. Which of the following standards addresses appropriate CLT adhesive performance for tall mass timber buildings? a.apa PRG b.apa PRG c. APA PRG d.any of the above standards are suitable 46

47 This concludes the American Institute of Architects Continuing Education Systems Course T h i s p r e s e n t a t i o n i s p r o t e c t e d b y U S a n d I n t e r n a t i o n a l C o p y r i g h t l a w s. R e p r o d u c t i o n, d i s t r i b u t i o n, d i s p l a y a n d u s e o f t h e p r e s e n t a t i o n w i t h o u t w r i t t e n p e r m i s s i o n o f A m e r i c a n W o o d C o u n c i l ( A W C ) i s p r o h i b i t e d. A m e r i c a n W o o d C o u n c i l