Abstract
Steel moment frames develop large drift capacity and dissipate seismic energy through inelastic deformation in the plastic hinge region near the beam-to-column connection. To discourage fracture in this region, known as the protected zone, attachments are limited to arc spot welds and power-actuated fasteners for decking attachment. Other attachments or defects like shear studs, bolts, holes, gouges, and notches must be removed and repaired by grinding or by a combination of grinding and welding. These requirements are given in the AWS D1.8/D1.8M seismic welding code, but there have been no full-scale connection tests with these repairs in the plastic hinge region. For that reason, this research evaluated the performance of moment connections with repairs by testing six full-scale reduced beam section moment connections with and beams. The following defects and repairs were included in the beam protected zone: 3.17-mm ()-deep notches repaired by grinding, 6.35-mm ()-deep notches repaired by welding, and sharp 6.35-mm and 9.53-mm ( and ) semicircular notches. The specimens were tested in an exterior column configuration and subjected to the cyclic special moment frame qualification displacement protocol given in ANSI/AISC 341. All four specimens with repairs maintained substantial flexural strength through cycles of 5% story drift ratio and satisfied special moment frame qualification criteria. It is concluded that the AWS D1.8/D1.8M repairs resulted in sufficient ductility for use in special moment frames within the range of parameters tested. The two specimens with unrepaired sharp notches experienced fractures propagating from the notches, causing substantial loss of flexural strength during cycles of 3% or 4% story drift ratio.
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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.
Acknowledgments
This research was supported by the American Institute of Steel Construction, with in-kind funding provided by Nucor-Yamato Steel and Cives Steel Company.
References
Abbas, E., and M. R. Eatherton. 2014. A low cycle fatigue testing framework for evaluating the effect of artifacts on the seismic behavior of moment frames. Blacksburg, VA: Virginia Tech.
AISC. 2016a. Prequalified connections for special and intermediate steel moment frames for seismic applications. ANSI/AISC 358-16. Chicago: AISC.
AISC. 2016b. Seismic provisions for structural steel buildings. ANSI/AISC 341-16. Chicago: AISC.
ASTM. 2016a. Standard practice for magnetic particle testing. ASTM E3024/E3024M-16. West Conshohocken, PA: ASTM.
ASTM. 2016b. Standard test methods for tension testing of metallic materials. ASTM E8/E8M-16ae1. West Conshohocken, PA: ASTM.
ASTM. 2018. Standard test methods for notched bar impact testing of metallic materials. ASTM E23-18. West Conshohocken, PA: ASTM.
AWS (American Welding Society). 2016. Structural welding code-seismic supplement. AWS D1.8/D1.8M:2016. Miami: AWS.
Civjan, S. A., M. D. Engelhardt, and J. L. Gross. 2000. “Retrofit of pre-Northridge moment-resisting connections.” J. Struct. Eng. 126 (4): 445–452. https://doi.org/10.1061/(ASCE)0733-9445(2000)126:4(445).
Eatherton, M. R., R. T. Stevens, and T. M. Murray. 2022. Eight bolt extended stiffened end-plate moment connection tests with built-up and rolled beams. Blacksburg, VA: Virginia Tech.
Engelhardt, M. D., M. J. Venti, G. T. Fry, S. L. Jones, and S. D. Holliday. 2000. Behavior and design of radius cut reduced beam section connections. Sacramento, CA: SAC Joint Venture.
Florig, S. H., and M. R. Eatherton. 2015. Evaluation of the effect of boat-shaped welds and pneumatic power actuated fasteners on the seismic behavior of moment frames. Blacksburg, VA: Virginia Tech.
Hajjar, J. F., R. T. Leon, M. A. Gustafson, and C. K. Shield. 1998. “Seismic response of composite moment-resisting connections II: Behavior.” J. Struct. Eng. 124 (8): 877–885. https://doi.org/10.1061/(ASCE)0733-9445(1998)124:8(877).
Leon, R. T., J. F. Hajjar, and M. A. Gustafson. 1998. “Seismic response of composite moment-resisting connections II: Performance.” J. Struct. Eng. 124 (8): 868–876. https://doi.org/10.1061/(ASCE)0733-9445(1998)124:8(868).
Popov, E. P., T.-S. Yang, and S.-P. Chang. 1998. “Design of steel MRF connections before and after 1994 Northridge earthquake.” Eng. Struct. 20 (12): 1030–1038. https://doi.org/10.1016/S0141-0296(97)00200-9.
Ricles, J. M., C. Mao, L-W. Lu, and J. W. Fisher. 2000. Development and evaluation of improved ductile welded unreinforced flange connections. Sacramento, CA: SAC Joint Venture.
Stevens, R. T., M. H. Hebdon, and M. R. Eatherton. 2021. Evaluating the fracture potential of steel moment connections with defects and repairs. Blacksburg, VA: Virginia Tech.
Toellner, B. W., C. E. Watkins, E. K. Abbas, and M. R. Eatherton. 2015. “Experimental investigation on the seismic behavior of steel moment connections with decking attachments.” J. Constr. Steel Res. 105 (Mar): 174–185. https://doi.org/10.1016/j.jcsr.2014.11.006.
Tremblay, R., and A. Filiatrault. 1997. “Seismic performance of steel moment resisting frames retrofitted with a locally reduced beam section connection.” Can. J. Civ. Eng. 24 (1): 78–89. https://doi.org/10.1139/l96-084.
Tremblay, R., N. Tchebotarev, and A. Filiatrault. 1997. “Seismic performance of RBS connections for steel moment resisting frames: Influence of loading rate and floor slab.” In Proc., Behaviour of Steel Structures in Seismic Areas (STESSA ‘97) Conf. Milan, Italy: Edizioni.
Uang, C.-M., and D. Bondad. 1996. Static cyclic testing of pre-Northridge and haunch repaired steel moment connections. Rep. No. SSRP-96/02. La Jolla, CA: Univ. of California, San Diego.
Wulpi, D. J. 1985. Understanding how components fail. Novelty, OH: ASM International.
Youssef, N. F. G., D. Bonowitz, and J. L. Gross. 1995. A survey of steel moment-resisting frame buildings affected by the 1994 Northridge earthquake. Gaithersburg, MD: Building and Fire Research Laboratory, NIST.
Zapffe, C. A., and C. E. Sims. 1940. “Defects in weld metal and hydrogen in steel.” Am. Welding Soc. Welding 19 (Feb): 377–395.
Zapffe, C. A., and C. E. Sims. 1941. “Hydrogen embrittlement, internal stress and defects in steel.” Trans. Aime 145 (Feb): 1–37.
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© 2024 American Society of Civil Engineers.
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Received: Jul 7, 2023
Accepted: Dec 20, 2023
Published online: Mar 13, 2024
Published in print: May 1, 2024
Discussion open until: Aug 13, 2024
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