blast-resistant testing for massive timber exterior wall
TRANSCRIPT
Blast-Resistant Testing for Massive Timber Exterior Wall: Expanding Timber Opportunities In North America November 2015 – Mass Timber Workshop
B-15-91.1
© 2015 Karagozian & Case, Inc.
Karagozian & Case, Inc. 700 N. Brand Blvd. Glendale, CA 91203 818-240-1919 www.kcse.com WoodWorks – Wood Products Council www.woodworks.org University of Maine Orono, ME 04469 www.umaine.edu
By: Lisa Podesto, P.E. (WW) Dr. Edwin Nagy, Ph.D., P.E., S.E. (UMaine) Mark Weaver, P.E., S.E. (K&C) Leonardo Torres, P.E., S.E. (K&C) Garry D. Myers, P.E., S.E. (K&C)
B-15-91 pg 2 Project Objectives
Expand market opportunities for wood construction in Department of Defense and growing civilian markets requiring blast resistant structures.
Work with the Army Corps of Engineers Protective Design Center to develop an acceptable mass timber blast resistant alternative to steel and masonry.
Create a basis for inclusion of mass timber solution(s) in the Unified Facilities Criteria’s conventional construction provisions.
B-15-91 pg 3 Project Deliverables
Develop analytical methodologies to analyze CLT for blast loads. Both SDOF and high-fidelity physics-based (HFPB) FE methods will be developed.
Conduct static and dynamic CLT testing that tests / improves developed analytical methodologies.
Document analytical methodologies and test data in a form that could be used in blast analysis by structural engineers and potentially incorporated into SBEDS.
Establish a foundation for characterizing material dynamic response of Nail Laminated Timber walls.
B-15-91 pg 4
Conduct literature review.
Develop preliminary SDOF analysis methodology.
Define target conventional CLT construction.
Create HFPB FE CLT model.
Perform static CLT testing.
Refine SDOF and HFPB FE analysis methodologies.
Perform dynamic CLT testing.
Document literature review, analysis methodologies, and testing results in report form.
Publicize findings of effort.
Project Overview Approach & Organizational Chart
B-15-91 pg 5
Literature Review Overview
Sources Sought Published testing results that document out-of-plane response of
CLT. Case studies that document the usage of CLT in practice. CLT standards and design aids.
Conclusion Limited published test results that documents out-of-plane
response of laminated timber exposed to high-strain rates.
B-15-91 pg 6
Preliminary Scoping Analyses Single Degree-of-Freedom
Preliminary Assumptions Ultimate resistance, ru, and equivalent stiffness, k, derived
using “shear analogy” method (Kreuzinger, 1999). Both flexural and shear stiffness were used to derive equivalent
stiffness.
Residual resistance, rr, derived assuming innermost ply(s) provides flexural strength.
Assume immediate softening stiffness is equivalent to initial stiffness.
Static increase factor (from ANSI/APA PRG 320-2012) 2.1 for out-of-plane flexure. 3.15 for out-of-plane shear.
Dynamic increase factor set equal to one and CD = 1 Response limit: Ductility, µ = 1 (i.e., elastic response only).
All of the above assumptions will be investigated via the UMaine static testing and ideally refined based on uOttawa and PDC CLT testing.
k k
ru
rr
∆e ∆r
Outermost CLT ply ruptures
Innermost CLT ply ruptures
Schematic SDOF Flexural Resistance Function for 3-Ply CLT
B-15-91 pg 8
Preliminary Scoping Analyses Supported Weight: Wood Panel (i.e., 10 psf)
EWII
EWI 32’
75’
43’
60’
81’ 104’
146’
200’
B-15-91 pg 9
Preliminary Scoping Analyses Supported Weight: Brick Veneer (i.e., 44 psf)
EWII
EWI
23’
28’
42’
53’
53’
67’
100’ 127’
B-15-91 pg 10
Preliminary Scoping Analyses Proposed Conventional Construction Options
Wall Type Sections Span
Min. Static
Material Strength
EWI Standoff Distance
EWII Standoff Distance
Reinforced Concrete ≥ 6” 12’ – 20’ 3,000 psi 66 16
CLT – Brick Veneer (44 psf) 5-ply 10’ – 14’ Grade E1 53 23
CLT – Brick Veneer (44 psf) 3-ply 10’ – 14’ Grade E1 67 28
Reinforced Masonry 8” – 12” 10’ – 14’ 1,500 psi 86 30
CLT – Wood Panel (10 psf) 5-ply 10’ – 14’ Grade E1 75 32
Wood Studs – Brick Veneer 2x4 & 2x6 8’ – 10’ 875 psi 105 36
CLT – Brick Veneer (44 psf) 5-ply 10’ – 14’ Grade V2 100 42
CLT – Wood Panel (10 psf) 3-ply 10’ – 14’ Grade E1 104 43
CLT – Brick Veneer (44 psf) 3-ply 10’ – 14’ Grade V2 127 53
CLT – Wood Panel (10 psf) 5-ply 10’ – 14’ Grade V2 146 60
Steel Studs – Brick Veneer 600S162-43; 600S162-54; 600S162-68 8’ – 12’ 50,000 psi 187 75
CLT – Wood Panel (10 psf) 3-ply 10’ – 14’ Grade V2 200 81
Wood Studs – EIFS 2x4 & 2x6 8’ – 10’ 875 psi 207 86
Steel Studs – EIFS 600S162-43; 600S162-54; 600S162-68 8’ – 12’ 50,000 psi 361 151
B-15-91 pg 11
Proposed Static CLT Testing Overview
Objective: Investigate out-of-plane behavior of CLT for different conventional connection configurations.
Tests will be used to develop resistance functions for SDOF analysis.
5 to 7 days of testing at University of Maine.
Proposed panel: 3-ply (and/or 5-ply), two different grades, 4’x8’ specimen size.
Two connection configurations to be tested (likely self-tapping screws & brackets).
Baseline (i.e., roller supports)
Brackets (weaker)
Brackets (stronger)
B-15-91 pg 12
Proposed Static CLT Testing Test Jig Concept
Panels w/o Connections water bladder
water bladder
Deflection gage
Panels w/ Connections
Reaction floor
Reaction floor
B-15-91 pg 13
Objective To demonstrate the blast resistance capability of cross-laminated timber (CLT) via a live blast
field full-scale test. To validate SDOF and HFPB FE analysis methodologies.
Peak Blast Load EWII at 30-ft
Test Configuration Options Option 1: One (or two) 1- to 2-story, 30’x15’ two bay CLT structures. Option 2: (24) 4’x10’ panels supported by previously constructed reaction structures. For
purposes of cost, assume 3 panels are tested at a time.
Proposed CLT Dynamic Testing Overview
Opening
CLT Partition
1st Shot
2nd Shot
OPTION 1 CONFIGURATION