Looking Forward: Leading Edge Solutions through Applied Research in Wood Building Systems

Transcription

1 Looking Forward: Leading Edge Solutions through Applied Research in Wood Building Systems Weichiang Pang, Ph.D. Associate Professor Glenn Department of Civil Engineering Dustin Albright, Assistant Professor School of Architecture Clemson University, Clemson, South Carolina Disclaimer: This presentation was developed by a third party and is not funded by WoodWorks or the Softwood Lumber Board. [Wood Solutions Fair 2017, Nov-2 Charlotte, NC]

2 The Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider #G516. 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. 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.

3 Course Description The recent renaissance in wood construction demands applied research and creative collaborations between the wood products industry, engineers and designers to devise new solutions. This is a two-part presentation that covers two different engineered solutions, one for mass timber and the other for light-frame construction. Part I discusses the development of a preassembled crosslaminated timber and glulam composite floor system for mass timber construction and discusses relevant vibration and serviceability issues. Part II focuses on a new flat-packed light-framing system that promotes rapid assembly and easy disassembly, while maintaining the highest level of energy performance.

4 Learning Objectives 1. Learn about serviceability and vibration characteristics of CLT floor systems 2. Learn about hybrid, long-span massive timber flooring systems, punctuated by a detailed case-study involving a 40ft long x 5ft wide CLT-glulam composite system 3. Learn about current building code challenges and solutions on the horizon 4. Learn about energy efficient wall and roof assemblies using a unique prefabricated light framing system

5 Part I : CLT-Glulam Composite Deck - An Alternative to Pre-cast Concrete Deck Weichiang Pang, Associate Professor Mengzhe (Eric) Gu, Post-doctoral Research Associate Pre-assembled composite timber deck system an alternative to pre-case concrete deck Evaluate the vibration and serviceability performances Determine the moment and shear capacities

6 What is Cross-Laminated Timber (CLT) CLT is a prefabricated solid engineered wood panel Three or more orthogonally bonded layers of solid sawn lumber or structural composite lumber (SCL) Laminated by gluing the longitudinal and transverse layers with structural adhesive 2015 IBC / NDS

7 Advantages of CLT Prefabrication allows fast construction on site Dimensional stability and controlled panel tolerance Light weight and high strength-to-weight ratio (1/3 of concrete weight) A sustainable and renewable material (carbon negative) Carbon storage of wood (Kolb 2008) 0.9 metric ton=2200 lbm

8 Carbon Footprint of a 20-story Building North America forests can grow a 20-story wood building every ~15 min. CO 2 Emissions A 20-Story wood building sequesters ~3000 tons CO cars removed from the road for one year [Green 2013]

9 CLT-Glulam Composite Deck Target Design Parameters: Span 40 Loads: 20 psf dead load and 100 psf live load Width: 5 ft Depth: 20 inches Flanges: V3 3-ply Southern Pine CLT Webs: 24F-V4-1.7E Glulam

10 Timber-to-Timber Joint w/ Inclined Screws Tension Joint Compression Joint Crossed Joint

11 Connection Tests Inclined Screws Different screw types Different angles 45 o 30 o 90 o Different sizes Acoustic membrane Combination of Screw and Glue

12 Inclined Screw Joints Strength vs. Ductility 30⁰ installation angle was selected in the final design [Montgomery 2014]

13 Connection Test (ASSY VG 3/8 at 30⁰)

14 Vertical Shear and Bending Strengths Capacities were calculated assuming full composite using 2015 NDS Tests were later conducted to examine the level of composite action [Gu 2017]

15 Deflections Capacities were calculated assuming full composite using 2015 NDS Tests were later conducted to examine the level of composite action [Gu 2017]

16 Interface / Horizontal Shear Design Tested ultimate strength of screw was used in the design Interface Shear Demand Capacity Max. Spacing Allowed 4 o.c. 6 o.c. 10 o.c.

17 Final Details

18 Assembling of CLT-Glulam Composite Beam

19 Assembling of CLT-Glulam Composite Beam

20 Assembling of CLT-Glulam Composite Beam

21 Assembling of CLT-Glulam Composite Beam

22 Vibration Test Timber floors may be prone to vibration issue Source: walking, dancing, machinery Consequence: Headache, nausea, loss of rent

23 Vibration Performance Guide [GD111997]

24 Instrumented Heel Drop Test Excitation measurement: Force Plate Response measurement: Accelerometers

25 Experimental Modal Analysis

26 Instrumented Heel Drop Test DOF 61 Stationary input, roving response Excitation is fixed at DOF 61 array of 4 accelerometers swept through the test floor Row3 Row2 Row1 DOF 61

27 Instrumented Heel Drop Test Record length= 40s Bandwidth=30 Hz Resolution=0.025Hz Repeat times=5/dof

28 Consistency of the Heel Drop Impacts

29 Two Boundary Conditions Pinned Clamped

30 Instrumented Heel Drop Test Raw Data 156 Response Measurements

31 Spectrogram (inverted waterfall plot) BC: Clamped

32 Extraction of Natural Frequencies and Damping Composite FRFs Peak picking for natural frequencies Half-power bandwidth for damping BC: Clamped

33 Mode2: Torsion Mode2: Torsion Mode1: 1 st Bending 7.2Hz Mode4: 2 nd Torsion 24.0Hz Mode2: Torsion Mode2: Torsion Mode2: Torsion 15.8Hz Mode3: Bending 20.5Hz BC: Clamped

34 Natural Frequencies and Damping Ratios

35 Finite Element Model Red: layer shell elements Blue: frame elements Green: link elements

36 FE Model v.s. Test Results

37 Composite Action 9.5Hz 4Hz

38 Vibration Test Results Outdoor Footbridge Shopping Malls Office and Residential

39 Bending Test

40 Bending Test Video

41 Bending Test Result Bending Over-strength Ω= x Service Load Service Load 3.80 x service load 2.54 x design factored load Screws performed well

42 Interface Slip (Load-Slip of Screws) Interface Slips Ultimate Screw Connection Test Force-Displ Curve Ultimate Service Load Service Load

43 Mid-span CLT Failure Failures at: Finger joint failure Lumber knot failure

44 Bending Failure Modes

45 Mid-span Glulam Rolling Shear

46 Shear Test Video

47 Shear Test Sufficient Shear Capacity Shear Over-strength Ω= 6.15 Delamination and rolling shear failures Zone II (6 o.c.) screw failure

48 Shear Failure CLT Delamination at 79.1 kip

49 Summary and Concluding Remarks Pre-assembled CLT-Glulam Composite Deck An alternative to pre-cast concrete deck system Design span = 40 ft Dead load = 20 psf Live Load = 100 psf Bending over-strength = 2.54 Shear over-strength = 6.15 Need to consider vibration and serviceability

50 Potential Applications Multi-story apartments Multi-story offices Hotels / motels Parking garages Podium for supporting lightframe construction Short-span bridges

51 More Information, Free Download at

52 LOOKING FORWARD Digital Fabrication and Light Frame Technologies

53 DAN HARDING DAVID PASTRE DUSTIN ALBRIGHT ULRIKE HEINE VINCENT BLOUIN

54 The challenge for the next generation is to pursue a deeper engagement with the techniques of fabrication and an expansion of the range of issues that the experimental impulse is poised to tackle. Barry Bergdoll, Home Delivery

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57 AVG. WEIGHT OF HOUSE = 48,590 lbs (single story, 970 ft 2 ) 2300 miles BY TRUCK: 2, 300 miles ( 3, 701km) = tonnes of CO 2 emitted BY TRAIN: 2, 300 miles ( 3, 701km)= 2. 6 tonnes of CO 2 emitted

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61 CONCERNS REGARDING EXECUTION accurate measuring and cutting is difficult for unskilled laborers conventional tools (saws and nail guns) are dangerous and loud nails make the construction irreversible (cannot be easily disassembled) wall and roof panels are still heavy to move and difficult to set without heavy external equipment

62 CONCERNS REGARDING THERMAL PERFORMANCE limited cavity depth thermal bridging LARSEN TRUSS

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64 AVG. WEIGHT OF HOUSE = 48,590 lbs (single story, 970 ft 2 ) BY TRUCK: 2, 300 miles ( 3, 701km) = tonnes of CO 2 emitted BY TRAIN: 2, 300 miles ( 3, 701km)= 2. 6 tonnes of CO 2 emitted BY TRUCK: miles ( km) = tonnes of CO 2 emitted (from Riverside, CA)

65 DIGITALLY FABRICATED HOUSE FOR NEW ORLEANS Lawrence Sass MIT

66 DIGITALLY FABRICATED HOUSE FOR NEW ORLEANS Lawrence Sass MIT

67 WIKIHOUSE Alastair Parvin + Nick Ierodiaconou London

68 WIKIHOUSE Alastair Parvin + Nick Ierodiaconou London

69 FACIT HOMES London / present

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72 Sim[PLY] FRAMING SYSTEM Clemson University

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76 Sim[PLY] JOINT FAMILY

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81 SHEAR CAPACITY: TAB + SLOT ASTM D Standard Test Methods for Mechanical Fasteners in Wood Avg. Ultimate Force = 1,021 lbs Avg. Displacement = 0.4 inches Factored Shear Capacity = 613 pounds Required Frequency = tabs per ft 2 (at E and W walls)

82 TENSILE CAPACITY: CABLE TIE ASTM D Standard Test Methods for Mechanical Fasteners in Wood Avg. Ultimate Tensile Capacity = 268 lbs Avg. Flange Displacement = 0.35 inches Frequency of Cable Ties Provided = 0.25/ft 2

83 SHEAR CAPACITY: SHEATHING SCREW ASTM D Standard Test Methods for Mechanical Fasteners in Wood Avg. Shear Force Resistance = 332 lbs Avg. Displacement = 0.50 inches Nominal Shear Capacity per Screw = 266 lbs

84 WITHDRAWAL CAPACITY: SHEATHING SCREW ASTM D Standard Test Methods for Mechanical Fasteners in Wood Avg. Ultimate Tensile Load = 397 lbs Avg. Displacement = 0.09 inches

85 RAFTER BENDING CAPACITY ASTM D Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Structural Material

86 RAFTER BENDING CAPACITY ASTM D Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Structural Material Avg. Ultimate Moment Capacity = 6,431 lbs-ft

87 SHEAR WALL RACKING ASTM E Standard Practice for Standard Load Test for Shear Resistance of Framed Walls for Buildings

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89 Avg. Ultimate Force= 1,230 plf At Δ = 0.2 inches, Avg. Load = 188 plf

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97 THE CHARLESTON FAB LAB, LLC North Charleston. SC July 2015

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120 Sim[PLY]: CURRENT + FUTURE intellectual property Sim[PLY] optimization Sim[PLY] parameterization Sim[PLY] hybridization looking for new opportunities for application and dissemination (including commercial and multifamily)

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123 Questions? This concludes The American Institute of Architects Continuing Education Systems Course Weichiang Pang Glenn Department of Civil Engineering Clemson University Dustin Albright School of Architecture Clemson University