PSI - Issue 17

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect v il l li t .sci c ir ct.c

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ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia .elsevier.co /locate/procedia

Procedia Structural Integrity 17 (2019) 674–681

ICSI 2019 The 3rd International Conference on Structural Integrity Mechanical Treatment of Crack-Arrest Holes Subjected to Distortion-Induced Fatigue Luke Bridwell a , William Collins a* , Caroline Bennett a , Jian Li a a University of Kansas Department of Civil, Enviromenal, and Architectural Engineering, 2150 Learned Hall 1530 W. 15 th St. Lawrence, KS 66045, United States Abstract Fatigue cracking is a major concern for many aging steel bridges in the United States. A common form of crack remediation is the drilling of crack-arrest holes, increasing the crack tip radius and thus reducing the applied stress intensity. However, the majority of cracking that occurs in bridge structures is caused by distortion-induced fatigue. Cross-frame forces generated by differential girder displacement produce multiaxial, mixed mode fatigue loading at the intersection of the girder web, flange, and connection plate, producing cracking along web-to-stiffener welds and flange to-web welds. Crack-arrest holes are often used as a first line of defense at these cracks. However, crack-arrest holes deform out-of-plane under distortion-induced fatigue loading, and have been found to be of limited utility in this application. Previous research has shown that mechanical treatment of crack-arrest holes has the potential to improve the efficacy of crack-arrest holes for halting crack propagation for in-plane fatigue, but the performance of such treatments is unknown for distortion-induced fatigue cracks. A research program sponsored by the Kansas Department of Transportation is investigating the effectiveness of one such technology for controlling crack propagation in steel bridge girders susceptible to distortion-induced fatigue. This technology produces a cold-worked region around the crack-arrest hole, introducing a field of compressive residual stresses aimed at retarding crack propagation. Evaluation of the mechanically treated crack-arrest holes is evaluated analytically for both in-plane and out-of-plane fatigue loading. This paper presents background on the problem and preliminary findings of the study. I I r I t r ti l f r tr t r l I t rit i l t t t l j t t i t ti ti Bri w ll a , illi lli a* , r li ett a , i i a a niversity of ansas epart ent of ivil, nviro enal, and rchitectural ngineering, 2150 Learned all 1530 . 15 th St. La rence, S 66045, nited States stract atigue cracking is a ajor concern for any aging steel bridges in the nited tates. co on for of crack re ediation is the drilling of crack-arrest holes, increasing the crack tip radius and thus reducing the applied stress intensity. o ever, the ajority of cracking that occurs in bridge structures is caused by distortion-induced fatigue. ross-fra e forces generated by differential girder displace ent produce ultiaxial, ixed ode fatigue loading at the intersection of the girder eb, flange, and connection plate, producing cracking along eb-to-stiffener elds and flange to- eb elds. rack-arrest holes are often used as a first line of defense at these cracks. o ever, crack-arrest holes defor out-of-plane under distortion-induced fatigue loading, and have been found to be of li ited utility in this application. revious research has sho n that echanical treat ent of crack-arrest holes has the potential to i prove the efficacy of crack-arrest holes for halting crack propagation for in-plane fatigue, but the perfor ance of such treat ents is unkno n for distortion-induced fatigue cracks. research progra sponsored by the ansas epart ent of ransportation is investigating the effectiveness of one such technology for controlling crack propagation in steel bridge girders susceptible to distortion-induced fatigue. his technology produces a cold- orked region around the crack-arrest hole, introducing a field of co pressive residual stresses ai ed at retarding crack propagation. valuation of the echanically treated crack-arrest holes is evaluated analytically for both in-plane and out-of-plane fatigue loading. his paper presents background on the proble and preli inary findings of the study.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2019 he uthors. ublished by lsevier . . eer-revie under responsibility of the I I 2019 organizers. 019 The Authors. Published by Elsevier B.V. eer-review under responsibility of the ICSI 2019 organizers.

Keywords: fatigue; distortion-induced fatigue; steel; bridge; girder ey ords: fatigue; distortion-induced fatigue; steel; bridge; girder

* Corresponding author. Tel.: 1-785-864-0672. E-mail address: william.collins@ku.edu * orresponding author. el.: 1-785-864-0672. - ail address: illia .collins ku.edu

1. Introduction . I tr cti

Fatigue cracking is a major concern for aging steel highway bridges. Primarily controlled by differential girder displacement through a mechanism known as distortion-induced fatigue, the majority of cracks are driven by out-of-plane loading. Although many crack remediation methods exist for in-plane cracking, the effectiveness of these methods on out-of-plane cracking is unknown. One such methodology uses a mechanical process to apply plastic deformations to a crack-arrest hole, resulting in a compressive residual stress field around the hole. This paper presents a brief background into fatigue cracking of steel highway bridges, common fatigue crack ati e crac i is a aj r c cer f r a i steel i a ri es. ri aril c tr lle iffere tial ir er is lace e t t r a ec a is as ist rti -i ce fati e, t e aj rit f crac s are ri e t- f- la e l a i . lt a crac re e iati et s e ist f r i - la e crac i , t e effecti e ess f t ese et s t- f- la e crac i is . e s c et l ses a ec a ical r cess t a l lastic ef r ati s t a crac -arrest le, res lti i a c ressi e resi al stress fiel ar t e le. is a er rese ts a rief ac r i t fati e crac i f steel i a ri es, c fati e crac

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 2019 he uthors. Published by lsevier . . Peer-revie under responsibility of the I SI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.090