Multi steel girder bridges experience differential deflection between adjacent girders when subject to vertical loads resulting in a driving force in crossframe diaphragms. Distortioninduced fatigue cracks mostly occur in older bridges with members prone to fatigue. Different models have been developed to investigate the behavior of bridges. Review of field measurements for distortioninduced. Distortioninduced fatigue in steel bridges is a continuing problem for bridge engineers. Recently, a noncomposite steel girderfloorbeamstringer bridge in pennsylvania has experienced previously unanticipated fatigue cracking. Therefore, fatigue cracks usually occur at the girder web gap due to outofplane distortion.
Distortion induced fatigue cracking has been observed in many kansas department of transportation kdot welded steel bridges due to the past use of fatigue prone connection plate details. Repairing distortioninduced fatigue in steel bridges using a cfrp. Nchrp project 12286, distortioninduced fatigue cracking in steel bridges. Girder bridges, steel bridges, distortion structural, steel plates, rehabilitation, fatigue life, fatigue tests, steel frames editorially related repairing distortioninduced fatigue cracks in steel bridge girders. This paper presents the results from computer simulations of 914 mm 36 in.
This phenomenon is termed distortioninduced fatigue. Many of the struc turally deficient bridges are over 50 years old. Optimization of retrofitting distortioninduced fatigue. Aug 04, 2016 this study examines the effect of a seismic retrofit on distortion induced fatigue cracking in a steel girder bridge in the midwestern united states. The driving force developed in the crossframe legs leads to outof. Girder differential deflection and distortioninduced. N2 the prevalence of fatigue cracking in steel bridge girders due to outofplane web distortion motivates development of procedures to evaluate the effects of distortional. As mentioned previously, the softening connection detail is costefficient and technical effective for retrofitting distortioninduced fatigue cracks in steel bridges.
Fatigue cracking detection in steel bridge girders through. Structural engineering conference speaker information. Analysis of vibration induced fatigue cracking in steel. Experimental program the purpose of the experimentalogramis to investigate pr the behavior of disto rtion. Evaluation and upgrading webgap distortion retrofits in. Special thanks are due various support personnel m fritz engineering laboratory. Fatigue is the main reason for the limited service life of welded plate girders built before the mid1970s. These options are adapted from the manual for repair and retrofit of fatigue cracks in steel bridges dexter and ocel 20 and are proposed as a guide for the detailing of repairs and retrofits for fatigue cracks. Although, current bridge design specifications provide estimates of fatigue life for loadinduced cases, fatigue cracking due to outofplane distortion is not adequately addressed, despite its severity. Distortioninduced fatigue cracking in older steel bridges is a primary concern for many bridge owners, accounting for the majority of fatigue cracks found on steel bridges. Repairing distortioninduced fatigue cracks in steel. This paper presents a support vector machine svm method for the detection of distortion induced fatigue cracking in steel bridge girders based on the data provided by selfpowered wireless sensors sws.
More details on the forming mechanism of these cracks can be found in. The basically horizontal cracking has occurred in floorbeam webs at girderfloorbeam connections. Fatigue life prediction for distortioninduced cracking of. Many steel bridges built before 1985 have experienced dif due to a lack of connection between connection stiffeners and. The experimental results showed that the cfrpsteel retrofit was effective in preventing distortioninduced fatigue crack propagation. Distortioninduced cracks have occurred in girder webs and gusset plates, usually in the short gaps between the end of a gusset plate or transverse stiffener and the girder flange. Enhancement of welded steel bridge girders susceptible to. One of the main sources of fatigue cracking is outofplane distortion occurring at connections of transverse structural members and longitudinal girders.
A working knowledge of fatigue susceptible details, aashto fatigue categorization, and nde methods and limitations is essential to the proper inspection of both new and in service. Steel research 12 1989 215228 distortioninduced fatigue cracking of bridge details with web gaps john w. Although, current bridge design specifications provide estimates of fatigue life for load induced cases, fatigue cracking due to outofplane distortion is not adequately addressed, despite its severity. In this study, an svmbased procedure has been proposed for the detection of fatigue cracking in steel girders based on the data of the sws. These occurances of cracking are often found at unstiffened gaps at the ends of connection plates of transverse and. Sensing distortioninduced fatigue cracks in steel bridges.
Identification and rehabilitation of fatigue details. Distortioninduced fatigue is a serious problem in bridges and is thought to be the cause of the majority of fatigue cracking observed in steel bridges. Inspecting steel bridges for fatigue pdf when cracks are discovered on bridges in service, fatigue is usually the cause. Distortioninduced fatigue is a serious national problem that is. Connor, rj, fisher, jw 2006 identifying effectives and ineffective retrofits for distortion induced fatigue cracking in steel bridges using field instrumentation. Consequently, the types of civil engineering applications that are susceptible to fatigue cracking include structures such as bridges, crane support structures, stacks and masts, and offshore structures. Distortioninduced fatigue cracking has been observed in many kansas department of transportation kdot welded steel bridges due to the past use of fatigue prone connection plate details. Results of the testing were compared to findings from finite element analyses, as well as findings from structural tests performed on 2.
Fatigue cracking detection in steel bridge girders through a. Distortion induced fatigue analysis of steel bridges. Distortion induced fatigue cracking in steel bridges. Although distortioninduced fatigue is a problem more frequent in steel girder bridges, it also has developed in many other types of bridges, such as trusses, suspension bridges, tied arch bridges and box girder bridges and have been known to crack frequently and relatively early in the service life of many bridges. The distortioninduced fatigue cracks may occur as horizontal or horseshoe cracks at the top or bottom of the girder to stiffener connections fig. Graduated students from fatigue and fracture research group. Currently, bridge owners, such as the state departments of transportation, rely on human inspection to detect, monitor, and quantify these cracks so that appropriate repairs can be applied before cracks reach critical sizes. Multigirder steel bridges designed prior to the mid1980s, have developed cracks due to distortioninduced fatigue. Distortioninduced fatigue cracking has been observed in many kansas department of transportation kdot welded steel bridges due to the past use of fatigueprone.
This paper presents a threedimensional 3d finite element. Pdf evaluation of a digital image correlation bridge. The ongoing research 1s sponsored through the national cooperative highway research program, as project 12286. This paper presents a threedimensional 3d finite element analysis fea of two. Development of fatigue cracking is affecting the structural performance of many of welded steel bridges in the united states. Four repair options were recommended to reduce stresses in the webgap region so that both crack initiation and crack growth could be prevented. Distor tioninduced fatigue cracking in steel bridges, few data exist on the fatigue strength and performance of attachments used to repair distortioninduced cracking. Distortion induced fatigue damage is a common problem in steel girder bridges built prior to the mid1980s. The university of kansas has studied and developed several retrofit techniques with an aim to determine the efficacy of different retrofit measures to mitigate the effects of distortion induced fatigue and stop fatigue crack growth or slow the rate of crack propagation. T1 girder differential deflection and distortion induced fatigue in skewed steel bridges. Distor tion induced fatigue cracking in steel bridges, few data exist on the fatigue strength and performance of attachments used to repair distortion induced cracking. Aug 29, 2019 distortion induced fatigue cracking in the unstiffened webgap of crossframe diaphragms is the most prevalent type of cracking in steel girder bridges.
Distortioninduced fatigue cracking in the unstiffened webgap of crossframe diaphragms is the most prevalent type of cracking in steel girder bridges. Despite various level of success of crack monitoring methods over the past decades, monitoring distortioninduced fatigue. The usual condition that produces fatigue cracking is the application of a large number of load cycles. Distortion induced cracks have occurred in girder webs and gusset plates, usually in the short gaps between the end of a gusset plate or transverse stiffener and the girder flange. T1 girder differential deflection and distortioninduced fatigue in skewed steel bridges. This type of fatigue damage occurs in crossframetogirder connections in an area called the web gap. Distortion induced fatigue cracking in aging steel bridges is a primary concern for many bridge owners and stakeholders, accounting for the majority of fatigue cracks in bridges in the united states.
Sensing distortioninduced fatigue cracks in steel bridges with. This specification is widely used in the united states, and the governing canadian specification is nearly identical to it. Consequently, the types of civil engineering applications that are susceptible to fatigue cracking include structures such as bridges. Distortioninduced fatigue cracking in steel bridges. Distortioninduced fatigue cracking from outofplane deformation in web gaps. These tests simulate the outofplane distortion at transverse connection plates. Distortioninduced fatigue dif cracking in steel bridges accounts for one of the most common types of fatigue damage in steel bridges in the united states. The tests verified that no fatigue crack growth had occurred in these bridge details after. When distortioninduced cracking develops in a bridge, usually large numbers of cracks form before correction action is taken because the cyclic stresses are usually high. Fatigue evaluation of steel bridges provides proposed revisions to section 7 fatigue evaluation of steel bridges of the american association of state highway and transportation officials manual for bridge evaluation with detailed examples of the application of the proposed revisions.
A new method for detection of fatigue cracking in steel. Kim roddis and yuan zhao, finite element analysis of retrofitting distortion induced fatigue cracking in welded steel bridges, journal of bridge engineering, american society of civil engineers, vol. Many of these aging bridges now require regular inspection and repair to address. Fatigue strength of steel bridge girders with distortion. Fatigue life prediction for distortioninduced cracking of steel bridges.
While a number of retrofit techniques exist for repairing distortioninduced fatigue cracking, many of them require partial or full bridge closure to perform the repair. Distortion induced fatigue cracking has become very prevalent in steel plate girder bridge members. When distortioninduced fatigue cracks do occur in skewed. A largescale computational study on distortioninduced fatigue in steel bridges, comprising more than 1,000 highresolution simulations of bridge. Distortioninduced fatigue cracking in a seismically. Such cracking is most likely to occur if the distortion must be accommodated in a short length of the web, such as in the gap between the end of transverse stiffeners and girder flanges, thats because the web gap is. In order to analyze the reason that cause web gap fatigue cracks and the type and location of cracks, a finite element model of one span of a steel. National steel bridge alliance american institute of steel.
Various available options for re pairing observed cracking in steel bridges are also presented. Outplane distortion induced fatigue analysis of steel bridges. Department of transportationinstability of composite steel plate girder bridges. Thus, the connection details of steel bridges subjected to outofplane.
A common form of crack remediation is the drilling of crack arrest holes, increasing the crack tip radius and. Fatigue evaluation of steel bridges the national academies. Trbs national cooperative highway research program nchrp report 721. Distortioninduced fatigue cracking in steel bridges book. Finite element analysis of outplane distortion induced. The fe studies were carried out on a doubledeck multigirder steel bridge experienced distortion induced fatigue cracking after the completion of a seismic retrofit. Distortioninduced fatigue cracking of a noncomposite. In the united states, many existing steel highway bridges were built from the late 1950s through the 1970s. Distortioninduced fatigue is a serious problem faced by many aging steel bridges, and the problem is often exacerbated in skewed bridges. The evaluation followed fhwanhi16016 document, design and evaluation of steel bridges for fatigue and fracture. A successful retrofitting may depend on the size of the cutoff, when a rectangular shape is adopted see fig.
Measures for distortion induced fatigue using finite element analysis was presented at the joint conference of the national steel bridge alliance and the world steel bridge symposium in april 2012. Finite element analysis of outplane distortion induced fatigue of welded steel bridge web. Inspecting steel bridges for fatigue cai purdue university. Many steel bridges in the united states designed before the mid1980s are highly susceptible to distortion induced fatigue cracking. Detection of fatigue cracking in steel bridge girders. Fatigue can cause steel members to crack and fracture. The results from this experie useful to mental study ar prevent cracks in ibeams of steel bridges, which could extend the fatigue life of steel bridges. Distortioninduced fatigue cracking in aging steel bridges is a primary concern for many bridge owners and stakeholders, a ccounting for the majority of fatigue cracks in. Many steel bridges built before 1985 have experienced dif due to a lack of connection between connection stiffeners and girder flanges. One of the main reasons of fatigue cracks on welded steel bridges is caused by outplane distortion. Many steel bridges in the united states designed before the mid1980s are highly susceptible to distortioninduced fatigue cracking. Girder differential deflection and distortioninduced fatigue. Such cracking is most likely to occur if the distortion must be accommodated in a short length of the web, such as in the gap between the end of transverse stiffeners and girder.
Modern steel construction april 2012 distortion induced fatigue is a serious problem in bridges and is thought to be the cause of the majority of fatigue cracking observed in steel bridges. Steel frames, fatigue life, fatigue tests, steel bridges, rehabilitation, distortion structural, girder bridges, steel plates editorially related repairing distortioninduced fatigue cracks in steel bridge girders using angleswithplate retrofit technique. Repairing distortioninduced fatigue cracks in steel bridge girders. Chapter 4 conclusions fatigue evaluation of steel bridges. Due to the lack of indepth research on the fatigue performance of connection details, a considerable number of these bridges have developed fatigue cracks caused by outofplane distortion.
The university of kansas has studied and developed several retrofit techniques with an aim to determine the efficacy of different retrofit measures to mitigate the effects of distortion induced fatigue and stop fatigue crack growth or slow. Transportation research board, national research council, 1990. Nchrp project 12286 was initiated with 3 primary objectives. Fatigue cracking is a major concern for many aging steel bridges in the united states. Review of field measurements for distortion induced fatigue cracking in steel bridges john w. The second part, finite element modeling techniques for crack prediction and. Pdf mechanical treatment of crackarrest holes subjected. The system was loaded to produce distortion induced fatigue cracking, and then the bridge was retrofitted with the newlydeveloped stiffenertoweb repair technique. Induced forces in secondary steel bridge members such as diaphragms and crossbracing can cause outofplane distortion in webs that may lead to fatigue cracking.
A fairly large number of welded steel bridge girders have developed fatigue cracking due to outofplane distortion. An analytical study on the outofplane distortion of a simple span four. Monitoring these fatigue cracks is essential to ensure bridge structural integrity. This stress, caused by stringer end rotation is not easily calculable therefore more detailed analysis techniques are needed to quantify connection behavior. Distortioninduced fatigue cracking has become very prevalent in steel plate girder bridge members. Jun 30, 2017 fatigue is the main reason for the limited service life of welded plate girders built before the mid1970s. Fatigue damage in steel bridges and extending their life 254 amplitude spectrum that the bridge was subjected to for over 20 years of service after treatment. This vulnerability is substantially increased if the outofplane driving force caused by differential girder displacement is increased for any reason. The cracking was believed to be associated with distortion induced fatigue, so a highly finemeshed 3d model of the structure was created to evaluate fatigue. Xiangxiong kong1, jian li1, william collins1, caroline bennett1. Distortioninduced fatigue cracking of bridge details with. Innovative retrofit technique for distortioninduced fatigue.
Graduated, 2015 a finiteelementbased approach to modeling cracking and repairs for distortion induced fatigue in steel bridges eric bonet, m. Graduated, 2014 utilizing fiberreinforced polymers to retrofit steel bridge girders damaged by fatigue loading say hak. Early detection of this condition would permit other potential crack locations to be. Consequently, fatigue cracking in these early structures was infrequent. Repairing distortioninduced fatigue cracks in steel bridge girders using angleswithplate retrofit technique. This type of fatigue cracking results from the threedimensional interaction this research was partially funded by the nsf engineering research center, advanced technology for large structural systems atlss at lehigh university. While a number of retrofit techniques exist for repairing distortion induced fatigue cracking, many of them require partial or full bridge closure to perform the repair. Sensing distortioninduced fatigue cracks in steel bridges with capacitive skin sensor arrays. The retrofits developed under tpf5189 are intended to be able to be installed with minimal disturbance to traffic. Experimental program the purpose of the experimentalogramis to. In this context, a major challenge is to predict the secondary stresses caused by outofplane distortion and consequently to analyze the resulting fatigue damage. Currently departments of transportation primarily use visual inspections to locate and characterize fatigue cracks. Distortioninduced fatigue is that due to secondary stresses in the steel plates that comprise bridge member crosssections diaphragms or lateral.
Repairs for this type of failure can be very costly. Many older steel girder bridges are affected by the distortion induced fatigue cracking. Fatigue stands for more than 90% of all damage cases reported in steel bridges. Fatigue evaluation of steel bridges provides proposed revisions to section 7fatigue evaluation of steel bridges of the american association of state highway and transportation officials manual for bridge evaluation with detailed examples of the application of the proposed revisions. Distortioninduced fatigue cracks caused by differential deflections between adjacent girders are common issues for steel girder bridges built prior to the mid1980s in the united states. Distortioninduced fatigue cracking at lateral gusset plate. Distortion induced fatigue dif cracking in steel bridges accounts for one of the most common types of fatigue damage in steel bridges in the united states. Steel frames, fatigue life, fatigue tests, steel bridges, rehabilitation, distortion structural, girder bridges, steel plates editorially related repairing distortioninduced fatigue cracks in steel bridge girders. Repair measures for a seismically retrofitted steel bridge. During the past 17 years, extensive fatigue cracking has devel oped in a wide variety of steel bridges because of unanticipated outofplane distortions. Review of field measurements for distortioninduced fatigue. Distortioninduced fatigue cracking of bridge details with web gaps. Cracking in details can take place in small unstiffened web gaps at which the deformation is concentrated. Distortion induced fatigue cracks represent the majority of fatigue cracks in steel bridges in the united states.
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