Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections

Steel structure flange connections are extensively employed in structural nodes due to their superior mechanical properties. This study combines fatigue testing and theoretical methods to investigate the fatigue performance of high-strength bolts in flange connections under actual gradient descent l...

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Main Authors: Huaguang Ni, Shujia Zhang, Honggang Lei
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Buildings
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Online Access:https://www.mdpi.com/2075-5309/14/12/3736
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author Huaguang Ni
Shujia Zhang
Honggang Lei
author_facet Huaguang Ni
Shujia Zhang
Honggang Lei
author_sort Huaguang Ni
collection DOAJ
description Steel structure flange connections are extensively employed in structural nodes due to their superior mechanical properties. This study combines fatigue testing and theoretical methods to investigate the fatigue performance of high-strength bolts in flange connections under actual gradient descent loads and provide fatigue design methods. Initially, fatigue tests were conducted on two sets of high-strength bolts under a gradient descent loading mode, yielding a total of 11 sets of fatigue data. Subsequently, the stress–life (S-N) curve was plotted using a cumulative damage model combined with an equivalent constant amplitude stress method, and the results were compared with existing fatigue design specifications. Additionally, digital cameras and electron microscopes were utilized to capture fatigue fracture images of the high-strength bolts, allowing a detailed investigation into the mechanisms underlying bolt fatigue fractures. The results indicate that the allowable stress amplitudes for the two sets of high-strength bolts, corresponding to a fatigue life threshold of 2 million cycles, were 144.211 MPa and 130.316 MPa, respectively—both of which exceed the values specified in current fatigue design codes. Moreover, finite element simulations revealed that the most pronounced stress concentration occurs at the first thread where the bolt and nut interface, which is identified as the critical location for fatigue fracture in bolts. The allowable stress and fatigue calculation method of bolts obtained in this study will provide a reference for flange node design
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spelling doaj-art-8654f93aa1124c66be2de2ced6b7e4642025-08-20T02:50:56ZengMDPI AGBuildings2075-53092024-11-011412373610.3390/buildings14123736Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange ConnectionsHuaguang Ni0Shujia Zhang1Honggang Lei2College of Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaCollege of Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaCollege of Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaSteel structure flange connections are extensively employed in structural nodes due to their superior mechanical properties. This study combines fatigue testing and theoretical methods to investigate the fatigue performance of high-strength bolts in flange connections under actual gradient descent loads and provide fatigue design methods. Initially, fatigue tests were conducted on two sets of high-strength bolts under a gradient descent loading mode, yielding a total of 11 sets of fatigue data. Subsequently, the stress–life (S-N) curve was plotted using a cumulative damage model combined with an equivalent constant amplitude stress method, and the results were compared with existing fatigue design specifications. Additionally, digital cameras and electron microscopes were utilized to capture fatigue fracture images of the high-strength bolts, allowing a detailed investigation into the mechanisms underlying bolt fatigue fractures. The results indicate that the allowable stress amplitudes for the two sets of high-strength bolts, corresponding to a fatigue life threshold of 2 million cycles, were 144.211 MPa and 130.316 MPa, respectively—both of which exceed the values specified in current fatigue design codes. Moreover, finite element simulations revealed that the most pronounced stress concentration occurs at the first thread where the bolt and nut interface, which is identified as the critical location for fatigue fracture in bolts. The allowable stress and fatigue calculation method of bolts obtained in this study will provide a reference for flange node designhttps://www.mdpi.com/2075-5309/14/12/3736steel structurehigh-strength boltfatigue testvariable amplitude fatigueflange connectionsS-N curve
spellingShingle Huaguang Ni
Shujia Zhang
Honggang Lei
Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
Buildings
steel structure
high-strength bolt
fatigue test
variable amplitude fatigue
flange connections
S-N curve
title Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
title_full Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
title_fullStr Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
title_full_unstemmed Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
title_short Experimental Study on Variable Amplitude Fatigue Performance of High-Strength Bolts in Steel Structure Flange Connections
title_sort experimental study on variable amplitude fatigue performance of high strength bolts in steel structure flange connections
topic steel structure
high-strength bolt
fatigue test
variable amplitude fatigue
flange connections
S-N curve
url https://www.mdpi.com/2075-5309/14/12/3736
work_keys_str_mv AT huaguangni experimentalstudyonvariableamplitudefatigueperformanceofhighstrengthboltsinsteelstructureflangeconnections
AT shujiazhang experimentalstudyonvariableamplitudefatigueperformanceofhighstrengthboltsinsteelstructureflangeconnections
AT hongganglei experimentalstudyonvariableamplitudefatigueperformanceofhighstrengthboltsinsteelstructureflangeconnections