Toe-Screwed Cross-Laminated Timber Connection Design and Nonlinear Modeling
Publication: Journal of Structural Engineering
Volume 146, Issue 6
Abstract
This research investigated the mechanical characteristics of cross-laminated timber (CLT) connections fastened with structural wood screws, also known as self-tapping screws (STS). The CLT connection assemblies were toe-screwed (TS) at 45° and cyclically tested in tension and in-plane shear to evaluate the failure modes and applicability as seismic connections in CLT shear walls. The connection assemblies were representative of full-scale CLT shear walls connected to CLT floors as often seen in platform construction. Toe-screwed CLT connections exhibited screw fracture, head pull-through, and pinched hysteresis loops. Mechanical connection properties and backbone curves were extracted for comparison with design estimates. A head pull-through design method was developed, which predicted peak strength within 5% of test results. Connection parameters for ASCE/SEI 41 idealized-component curves were presented for use in performance-based design nonlinear-static pushover analysis. Combining the presented ASCE/SEI 41 parameters with the proposed design method and test results provides a simple and reasonably accurate nonlinear toe-screwed connection response curve. Partially threaded washer-headed screws were found to be superior to fully threaded screws in seismic applications due to their 15 times greater ultimate deformation capacity, substantially greater energy dissipation, similar peak strength, and similar elastic stiffness. However, the yield strength of partially threaded STS was found to be 48% of the yield strength of fully threaded STS.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. These include, raw data, graphs, spreadsheets, Codes for models, and digital images.
Acknowledgments
The authors thank the undergraduates, especially Cody Knight, for their work during fabrication and testing, and Milo Clauson for his continuous guidance from the beginning to the end of the project. This project was funded by the US Department of Agriculture’s Agricultural Research Service (USDA ARS Agreement No. 58-0202-5-001).
References
Amini, M. O., J. W. van de Lindt, D. Rammer, S. Pei, P. Line, and M. Popovski. 2018. “Systematic experimental investigation to support the development of seismic performance factors for cross laminated timber shear wall systems.” Eng. Struct. 172 (Oct): 392–404. https://doi.org/10.1016/j.engstruct.2018.06.021.
ANSI/APA. 2017. Standard for performance-rated cross-laminated timber. ANSI/APA PRG 320. Tacoma, WA: APA–The Engineered Wood Association.
APA–The Engineered Wood Association. 2011. Wood and other materials used to construct nonresidential buildings. Tacoma, WA: APA–The Engineered Wood Association.
ASCE/SEI. 2017a. Minimum design loads and associated criteria for buildings and other structures. ASCE/SEI 7. Reston, VA: ASCE/SEI.
ASCE/SEI. 2017b. Seismic evaluation and retrofit of existing buildings. ASCE/SEI 41. Reston, VA: ASCE/SEI.
ASTM. 2011. Standard practice for establishing structural grades and related allowable properties for visually graded lumber. ASTM D245. West Conshohocken, PA: ASTM.
ASTM. 2017. Standard practice for establishing clear wood strength values. ASTM D2555. West Conshohocken, PA: ASTM.
ASTM. 2018. Standard test methods for cyclic (reversed) load test for shear resistance of walls. ASTM E2126. West Conshohocken, PA: ASTM.
AWC (American Wood Council). 2014. National design specification (NDS) for wood construction: With commentary. Leesburg, VA: AWC.
AWC (American Wood Council). 2018. “Tall mass timber code changes get final approval.” Accessed December 27, 2018. https://www.awc.org/news/2018/12/19/awc-tall-mass-timber-code-changes-get-final-approval.
Ceccotti, A., C. Sandhaas, M. Okabe, M. Yasumura, C. Minowa, and N. Kawai. 2013. “SOFIE project: 3D shaking table test on a seven-storey full-scale cross-laminated timber building.” Earthquake Eng. Struct. Dyn. 42 (13): 2003–2021. https://doi.org/10.1002/eqe.2309.
Dietsch, P., and R. Brandner. 2015. “Self-tapping screws and threaded rods as reinforcement for structural timber elements—A state-of-the-art report.” Constr. Build. Mater. 97 (Oct): 78–89. https://doi.org/10.1016/j.conbuildmat.2015.04.028.
Fitzgerald, D. 2019. Cross-laminated timber shear walls with toe-screwed and slip-friction connections. Corvallis, OR: Oregon State Univ.
Forest Products Laboratory. 2010. Wood handbook: Wood as an engineering material. Madison, WI: US Dept. of Agriculture.
Forest Products Laboratory. 2018. “2nd mass timber research workshop.” In Proc., Mass Timber Research Workshop. Madison, WI: USDA Forest Products Laboratory.
FPInnovations. 2013. CLT handbook, edited by E. Karacabeyli and B. Douglas. Pointe-Claire, QC: FPInnovations.
Fragiacomo, M., B. Dujic, and I. Sustersic. 2011. “Elastic and ductile design of multi-storey crosslam massive wooden buildings under seismic actions.” Eng. Struct. 33 (11): 3043–3053. https://doi.org/10.1016/j.engstruct.2011.05.020.
Gavric, I., M. Fragiacomo, and A. Ceccotti. 2014. “Cyclic behaviour of typical metal connectors for cross-laminated (CLT) structures.” Mater. Struct. 48 (6): 1–17. https://doi.org/10.1617/s11527-014-0278-7.
Gavric, I., M. Fragiacomo, and A. Ceccotti. 2015. “Cyclic behavior of typical screwed connections for cross-laminated (CLT) structures.” Eur. J. Wood Wood Prod. 73 (2): 179–191. https://doi.org/10.1007/s00107-014-0877-6.
Hossain, A., I. Danzig, and T. Tannert. 2016. “Cross-laminated timber shear connections with double-angled self-tapping screw assemblies.” J. Struct. Eng. 142 (11): 04016099. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001572.
Krawinkler, H., F. Parisi, L. Ibarra, A. Ayoub, and R. Medina. 2001. Development of a testing protocol for woodframe structures. Richmond, CA: Consortium of Univ. for Research in Earthquake Engineering.
Levy, E. G. 2013. Acceptance criteria for alternate dowel-type threaded fasteners-proposed revisions. ICC AC233. Country Club Hills, IL: International Code Council—Evaluation Services.
Loss, C., A. Hossain, and T. Tannert. 2018. “Simple cross-laminated timber shear connections with spatially arranged screws.” Eng. Struct. 173 (Oct): 340–356. https://doi.org/10.1016/j.engstruct.2018.07.004.
Mallo, L., and O. Espinoza. 2014. “Outlook for CLT.” BioResources 9 (4): 7427–7443.
Pei, S., J. W. Van De Lindt, M. Popovski, J. W. Berman, J. D. Dolan, J. M. Ricles, R. Sause, H.-E. Blomgren, and D. R. Rammer. 2016. “Cross-laminated timber for seismic regions: Progress and challenges for research and implementation.” J. Struct. Eng. 142 (4): E2514001. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001192.
Piazza, M., A. Polastri, and R. Tomasi. 2011. “Ductility of timber joints under static and cyclic loads.” Proc. Inst. Civ. Eng. Struct. Build. 164 (2): 79–90. https://doi.org/10.1680/stbu.10.00017.
Popovski, M., and I. Gavric. 2015. “Performance of a 2-story CLT house subjected to lateral loads.” J. Struct. Eng. 142 (4): E4015006. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001315.
Popovski, M., and E. Karacabeyli. 2012. “Seismic behaviour of cross-laminated timber structures.” In Proc., 15th World Conf. on Timber Engineering, 335–344. Tokyo: World Conference on Earthquake Engineering.
Ringhofer, A., R. Brandner, and G. Schickhofer. 2015. “Withdrawal resistance of self-tapping screws in unidirectional and orthogonal layered timber products.” Mater. Struct. 48 (5): 1435–1447. https://doi.org/10.1617/s11527-013-0244-9.
Shen, Y. L., J. Schneider, S. Tesfamariam, S. F. Stiemer, and Z. G. Mu. 2013. “Hysteresis behavior of bracket connection in cross-laminated-timber shear walls.” Constr. Build. Mater. 48 (Nov): 980–991. https://doi.org/10.1016/j.conbuildmat.2013.07.050.
Sullivan, K., T. H. Miller, and R. Gupta. 2018. “Behavior of cross-laminated timber diaphragm connections with self-tapping screws.” Eng. Struct. 168: 505–524. https://doi.org/10.1016/j.engstruct.2018.04.094.
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Published In
Journal of Structural Engineering
Volume 146 • Issue 6 • June 2020
Copyright
©2020 American Society of Civil Engineers.
History
Received: Feb 21, 2019
Accepted: Nov 20, 2019
Published online: Mar 26, 2020
Published in print: Jun 1, 2020
Discussion open until: Aug 26, 2020
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