Repairing cracked steel structures with carbon fiber patches. They were repaired by patching, and old steel bearings were replaced with rubber ones. Detection of fatigue cracking in steel bridge girders. Full girder depth fatigue crack of lafayette street bridge in st. Pdf rewelding repair effects on fatigue cracks in steel. Repair of fatigued steel bridge girders with carbon fiber strips. Although welding can be used to repair cracks effectively, there are other methods available. Therefore, fatigue cracks usually occur at the girder web gap due to out of plane distortion. Parameters of the experimental study included the retrofit configuration and length of the fatigue cracks. As a simple and easy method for repairing fatigue cracks, the repair method using externallybonded cfrp strips attracts attention, and we have developed a repair. Pdf fatigueprone details in steel bridges researchgate.
Cracks originating at weld beads on the sole plate. Heatstraightening repair of damaged steel bridge girders. In urban highway steel bridges, fatigue damage has occurred with an increase in traffic and the passage of overloaded vehicles. Finally, tests were conducted on fullscale cracked girders. There is a need to predict the fatigue life of the typical weld repairs. Fatigue sensitive details in aging steel girders is one of the common problems that structural engineers are facing today. Structural investigation and fullscale girder testing. Cracks in steel girders decreases the load bearing capacity of the superstructure and may lead to failure of the structure. The welds for these attachments are comparable to those used for transverse stiffeners and partial length cover plates. Therefore, fatigue cracks were expected to grow in. Manual for repair and retrofit of fatigue cracks in steel. Fatigue performance of repair welds barbara ann kelly lehigh university.
Pdf repairing distortioninduced fatigue cracks in steel. The plates will provide a load path around the crack. These cracks resulted from the high volume of truck traffic and the unanticipated low fatigue resistance of the large coverplated beams 5. Repair measures for a seismically retrofitted steel bridge. The 65foot welded span in the twospan steel bridge at the facility for accelerated service testing has developed two major web and tension flange cracks, as well as numerous cracks in secondary members, during 15 years of service under heavy axle load traffic. After the rewelding, other treatments were considered, including polishing, heat treatment. All cracks in the welded span appear to have initiated at weld details.
Repair of bridge structural steel elements manual page 1 1. May 05, 2014 repairing distortioninduced fatigue cracks in steel bridge girders using angleswithplate retrofit technique. The emphasis was placed on the distortioninduced fatigue cracks occurred at girder to stiffener connections. Guide 5 1 introduction throughout this guide, commentary and reference to the supporting nchrp 2007 task 307 final report referred to as the report are made by section number in square brackets. Sncurve comparing the two types of steel for the repair welds 102. This report presents results from a laboratory study and field implementation of acoustic emission monitoring of fatigue cracks in coverplated steel bridge girders.
Task 387, maintenance actions to address fatigue cracking in steel bridge. Many steel bridges in the united states designed before the mid1980s are highly susceptible to distortioninduced fatigue cracking. The fatigue cracks were found in girders g1 and g7 at the end support p1871 of the threespan continuous steel deck plate girder bridge which was located on the westend side of this section. This guide serves to update the 1985 nchrp report 280. Fatigue crack repairs for structural steel general notes repair fatigue cracks. Specimens of ribtodeck welds and diaphragmtorib welds in steel bridge decks were tested to crack under cyclic load. Early in 1987, bridge inspection crews from the florida department of transportation discovered over 100 cracks in the steel box girders carrying the ramps of interstate highway 110 at its southern terminus in downtown pensacola, florida. The cause of the crack must be eliminated or mitigated for this to be successful. With cracks, ensure the weld penetrates the full depth of the crack. Air arc gouged flange of a beam for vee and weld repair, which was.
Stopping cracks in bridgesstructures many cracks are repaired by cutting out the crack and welding a repair patch in place or adding doublers can change the stiffness and dynamic response of the member most common method of preventing cracks from growing is by drill stop or crack arrest hole cah at the crack tip. Therefore, fatigue cracks usually occur at the girder web gap due to outofplane distortion. Several methods in practice aid in the detection of cracks, two of which are dye pen etrant and magnetic particle inspection. North american infrastructure, including steel bridges, are aging and reaching the end of their service lives.
The cracks on the webs of box girders are not apparently through type and do not show any signs of increasedecrease in length and width. This vulnerability is substantially increased if the outofplane driving force caused by differential girder displacement is increased for any reason. Absence of cracks or any other forms of distress in the cantilever portion and haunched portion of deck slab is indicative that those are not affected by heavier wheel loads or fatigue phenomenon. The first part describes finite element modeling techniques used to evaluate the potential for fatigue cracks in steel girders subjected to. Fatigue in concrete concerns security and stability of flyovers. Another lowfatiguestrength detail is the welded web gus set plate shown in figure 2. Crack detection in steel girders of bridges using a broken. Guide to recommended practice for the repair of impactdamaged prestressed concrete bridge girders prepared for the national cooperative highway research program transportation research board of the national academies kent a. Trbs national cooperative highway research program nchrp report 604. Floorbeam web gaps on tiedarch bridges, trusses, and plate girder bridges. The new repair method consists of adding steel angles connecting the girder web to the cross frame transverse connection plate cp, and a steel.
Fatigue strength of steel members with welded details. Over time, environmental stresses and cyclic truck traffic over bridges may lead to crack formation and crack propagation in the steel girders used in bridges. Although fatigue has not proved to be a problem to date for concrete structures, as structures are becoming more slender, the traffic volume is increasing, the axel loads are larger, and the traffic speed limits are higher, the margin of reserve. Short steel plates are often attached to the flange or web of beams and girders, serving as gussets or other connection plates. Different models have been developed to investigate the. This vulnerability is substantially increased if the out of plane driving force caused by differential girder displacement is increased for any reason. Chapter 11 structural repairs section 01 steel repairs. Innovative retrofit technique for distortioninduced fatigue. The acoustic monitoring successfully detected growing fatigue cracks in the lab when using both source location and a state of stress criteria.
Fatigue strength of steel girders strengthened with carbon fiber reinforced polymer patch m. Repair vs replace repair if in the twospan steel bridge at the facility for accelerated service testing has developed two major web and tension flange cracks, as well as numerous cracks in secondary members, during 15 years of service under heavy axle load traffic. Fatigue strength of steel girders strengthened with carbon. The following is a list of techniques described in a fatigue primer for structural engineers that have been used to successtully repair steel structures containing fatigue cracks. The new repair method consists of adding steel angles connecting the girder web to the cross frame transverse connection plate cp, and a steel plate on the opposite side of the girder web. The system was loaded to produce distortioninduced fatigue cracking, and then the bridge was retrofitted with the newlydeveloped stiffenertoweb repair technique. Replace removed steel portions with steel of the same. Figure 1 shows the major web and tension flange 8inch crack, which is very similar to the previous major web and tension flange crack that initiated in 1998 4. Acoustic emission monitoring of fatigue cracks in steel. Arresting cracks in steel bridges amazon web services. The two major cracks appear to have initiated by constraintinduced fracture cif. More details on the forming mechanism of these cracks can be found in. If crack growth is allowed to go on long enough, failure of the member can.
This study investigates the repair of steel bridge girders damaged by distortioninduced fatigue. Welded crane girders should be designed with heavier web plates so that the intermediate stiffeners can be eliminated. Repair of damaged steelconcrete composite girders using carbon fiberreinforced polymer sheets m. If damage to a bridge is left unrepaired, the condition of the components may further deteriorate resulting in a reduction. Fatigue in concrete concerns security and stability of. Chapter 11 structural repairs section 01 steel repairs srst. Availability statement fatigue cracks carbon fiber reinforced. Repairing distortioninduced fatigue cracks in steel bridge girders using angleswithplate retrofit technique.
Read chapter 7 fatigue and fracture of steel structures. Sha specifications dated may 2017 maintenance of traffic. Fatigue cracking in a bridge girder starting from weld defects at a weld. Physical simulations journal of structural engineering may 20. Using central tendency measurements, fatigue life data of steel. Repair assessment for distortioninduced fatigue cracks in. With holes, work the weld from the steel surface to the center of the hole ensuring no voids are allowed in the weld. Weld repair for fatiguecracked joints in steel bridges by applying. However, fatigue cracks were again found in the main girder support areas in october 2010.
Repairing distortioninduced fatigue cracks in steel. National steel bridge alliance american institute of steel. The plate girder specimen indicated that the fatigue lives of cracked joints are restored and also improved by weld repair with ltt welding wire. Analytical investigation of repair methods for fatigue cracks in steel bridges coadvisors. Fatigue performance of repair welds lehigh preserve. May 05, 2014 the new repair method consists of adding steel angles connecting the girder web to the cross frame transverse connection plate cp, and a steel plate on the opposite side of the girder web. This paper studies distortioninduced fatigue cracks in a 1960s era design missouri department of transportation modot welded plate girder bridge that developed cracks in the webgap region shortly after completion of a comprehensive seismic retrofit. Repairing distortioninduced fatigue cracks in steel bridge girders. Below are some crane girder design tips that may be of interest. Repair of fatigued steel bridge girders with carbon fiber. Statistical analysis of methods to repair cracked steel acting as if they are civil engineers, student teams perform statistical analyses of 12 data sets from seven research centers to quantify the mean fatigue life improvement of different methods to rehabilitate cracked steel. Maintenance actions to address fatigue cracking in steel bridge. Guidelines for evaluation and repair of prestressed concrete bridge members.
An introduction to steel bridge maintenance and repair. Repair of damaged steelconcrete composite girders using. Fatigue cracking in welded steel bridges transportation. Repair assessment for distortioninduced fatigue cracks in a. The fillet welds from the intermediate stiffeners create fatigue issues that result in. Control in steel bridge girders will be submitted for later publication. Fatigue and fracture performance explores limits, based on fatigue and fracture performance, on the number of damage and repair cycles to which damaged steel bridge girders may be subjected using the heat. The distortioninduced fatigue cracks may occur as horizontal or horseshoe cracks at the top or bottom of the girder to stiffener connections fig. The first part describes finite element modeling techniques used to evaluate the potential for fatigue cracks in steel girders subjected to distortioninduced fatigue.
Repairing distortioninduced fatigue cracks in steel bridge. The aging infrastructure of the united states requires signi. Repair of distortioninduced fatigue cracks on 5874344 over. Figure 2 sectional view of the superstructure inspection and repair histories every route of the hanshin expressway is inspected routinely and periodically. University of pittsburgh, pittsburgh pa richard miller, ph.
Trbs second strategic highway research program shrp 2 report s2r19arw2. Steel bridge design handbook december, 2015 engineering for structural stability in bridge construction. The fillet welds from the intermediate stiffeners create fatigue issues that result in base metal cracks in the girder webs. This paper studies distortioninduced fatigue cracks in a 1960s era design missouri department of transportation modot welded plate girder bridge that developed cracks in the webgap region shortly after completion of.
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