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29 to focus on a single field welded project performed by each of the six agencies and highlights key field welded practices implemented in these projects. Four of the six case examples involved repair cracking and other damage resulting from a collision with a bridge girder. One of the field welded case examples concerned repair cor- rosion damage on the ends of the beams and the sixth case example was a field welded repair of out-of-plane bending. CASE EXAMPLE 1âCONNECTICUT DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location Bridge No. 00299, which carries I-395 traffic southbound over Route 14 in Plainfield, Connecticut, is a three-span, steel, multi-girder bridge with a cast-in-place deck, with a total bridge length of 123 ft. The bridge was built in 1958 and rehabilitated in 1985. Field Welding Details The project involved the removal and repair in June 2014 of a crack in the bottom flange of a non-FCM steel girder resulting from collision damage. Temporary jacking tower and jack- ing assemblies were installed on either side of the crack. The jacking loads were increased until the crack in the flange was completely closed. Shim plates were then installed on the towers and the jacks unloaded. After the crack was removed, the bottom flange was repaired with a CJP groove weld, which conforms to weld detail B-U2a from the welding code, as shown in Figure 21. The backer bar was removed because of bridge clearance issues. The weld was finished smooth and flush with the base metal on all surfaces by grinding in the longitudinal direction of the girder. After NDT was performed and accepted, the jacks were loaded again to remove the shim plates before releasing the jacking loads, removing the jacking assemblies, and painting the structural steel. Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details There was easy access at the location because the repair was done over a two-lane road; traffic was alternated on the INTRODUCTION Individuals from six state agencies were interviewed by phone and e-mail for case examples in order to identify and collect additional information on the field welding practices incorpo- rated into specific projects. Information collected through the interviews included: ⢠Bridge type, layout, and location; ⢠Field welding details; ⢠Consideration of cost, timing, access, complexity, and alternate repair details; ⢠Field welding staff; ⢠Design methodology and preparation of plans and specifications; ⢠Welding code requirements; ⢠Inspection requirements; ⢠Quality control and quality assurance submittals: â Welder qualification, â Weld procedure, â Inspection procedure, and â Visual inspector and NDT qualifications; ⢠Field weld performance; and ⢠Suggested practices and lessons learned. The six state transportation agencies selected (Connecticut, Illinois, Maine, Massachusetts, Tennessee, and Texas) were chosen based on several factors including expressed willing- ness to provide additional information; and details on a field welded project including type of field welded repair, type of bridge, type of bridge member, year bridge was built, and geographic location. This information was captured through the state of practice survey and by direct contact. The survey included additional questions for agencies that had experience with field welding on a project that was or was not successful and expressed a willingness to discuss this experience. Case example participants were then asked to provide the name and location of the project, contact information for someone involved in the project, the reason field welding was used, the estimated number of welds, and whether the field weld- ing was or was not successful. A summary of the information acquired during the state of practice survey and case example interviews is presented in Table 1. The information presented in this chapter does not provide a comprehensive summary of the field welding practices of these six state agencies; rather, these case examples are intended chapter four CASE EXAMPLES
30 State Project Name Location/ Year Built Bridge Type Reason for Field Welding Estimated Number of Welds Success of Field Welding Connecticut Bridge No. 00299 I-395 Southbound over Route 14, Plainfield, CT 1958 3-span, steel, multi- girder with cast-in-place deck Crack in bottom flange from collision damage 1 very satisfied Illinois Structure No. 081-0011 I-80 over Mississippi River near Le Claire, IA 1966 16-span, steel, continuous, two-girder with 12 steel, multi- girder approach spans Rotation of floorbeam top flange at stringers caused fatigue cracking at web-to-flange fillet weld toe of floorbeam 828 very satisfied Maine Hinckley Rd. Repair I-95 NB over Hinckley Rd. Clinton, ME 1964 3-span, steel, multi- girder, rolled beam composite with cast-in- place deck Repair work on impact- damaged bridge 6 very satisfied Massachusetts Braga Bridge I-195 over Taunton River Fall River/Somerset, MA early 1960s 3-span, steel, continuous truss with steel, two- girder approach spans Corrosionâbeam end repairs many satisfied Tennessee Demonbreun St./I-40 Demonbreun St. over I-40 Nashville, TN 1969 2-span, steel, multi- girder, welded plate girder Collision repair 6 very satisfied Texas SH-124 at Intracoastal Waterway SH-124 over Intracoastal Waterway 50 mi. NE of Houston, TX 1978 Multi-span, steel, three- girder Vessel impact caused large cracks in plate girders 2 very satisfied TABLE 1 CASE EXAMPLES INTERVIEWED FIGURE 21 Connecticut DOT CJP weld repair sketch.
31 road below and a shoulder closure on the main road above. The entire repair was completed in one day. The DOT had a contractor under contract for this kind of work; only addi- tional line items on the contract needed to be approved by the contractor. Field Welding Staff The DOT intended to perform the field welded repair with state crews because the DOT has several certified field welders on staff; however, it encountered staffing issues. Therefore, an outside contractor, paid on an hourly basis, was hired for the field welding. Current Manual and Specifications Design Methodology and Preparation of Plans and Specifications The agency designed the field welded repair in-house; produc- ing jacking and welding procedures. The weldability of the steel was considered during the design phase and was determined by verifying the type of steel based on the original drawings. This procedure included a sketch of the repair detail, as shown in Figure 21, and notes on the specified welding code, repair procedure, and NDT requirements. The repair procedures were based on those that had been used on a previous project remembered by the bridge design office. It was noted that the welding procedure was controlled by the requirements speci- fied in the AWS D1.1 welding code, the jacking procedure was controlled by the AASHTO LRFD code for jacking loads, and the paint removal and re-application was done according to Connecticut DOT specifications. Welding Code Requirements The specified welding code used was AWS D1.1-1980 as modified by the AASHTO Standard Specifications for Weld- ing of Structural Steel Highway Bridges. The welding details, procedures, and testing methods conformed to these require- ments. This welding code was specified because it was on the original plan set that was used as a basis for the welding procedure. Quality Assurance and Quality Control Inspection Requirements The DOT provided in-house oversight for the repairs. A qual- ified inspector was on site each day. The DOT implemented visual inspection, ultrasonic testing of the repair weld, and magnetic particle testing to verify that the crack had been completely removed. Quality Control and Quality Assurance Submittals Table 2 contains a summary of the quality control and quality assurance repair and inspection procedures and qualifications. Performance of Repairs and Retrofits Performance of the Field Weld To date, the DOT reports that there have been no issues with the repair and that it was cost-efficient. The crack was in a location of a previous bridge hit, a tension location that has not propagated. Effective Practices Connecticut DOT does a significant amount of field welding and endorses it as a satisfactory repair method. The DOT list of the most effective practices for field welding are: ⢠Take the proper precautions and think about what needs to be done to support the repair welding, relieve the dead load and alleviate the live load if possible, ⢠Build temporary legs to support the girder on either side of the damaged area, and ⢠Move traffic from the lane over the affected girder. Lessons Learned The agency reported it would not vary the procedure from what they are currently doing. The design engineer noted that he would have liked to have revised the welding code to the latest version. Submittals Y/N Comments Field Procedures Y Written in-house and submitted to the contractor for review and agreement Welder Qualification Y Verified qualifications in-house Weld Procedure Y Formal WPS was not provided by the contractor, but the contractor used the owner submitted step-by-step procedures. Inspection Procedure Y Performed in-house by the DOT Visual Inspector Qualifications Y In-house visual NDT Qualifications Y In-house NDT TABLE 2 CONNECTICUT DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS
32 CASE EXAMPLE 2âILLINOIS DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location I-80 over the Mississippi River near La Claire, Iowa, is a 16-span, continuous steel, two-girder bridge, with 12 steel, multi-girder approach spans and a cast-in-place reinforced concrete deck. Total bridge length is 3,483 ft. The structure was built in 1966 and the current rehabilitation occurred in 2010. Field Welding Details The two girder spans consist of girders, floorbeams, and string- ers with a reinforced concrete deck. The bridge has cantilever floorbeam brackets on the exterior side of the main girders. An inspection performed in May 2009 discovered two top flanges cracked on the floorbeam brackets and one cracked floorbeam bracket web adjacent to the top flange. This dam- age required immediate action to stabilize the affected areas. Illinois DOT concluded that it was necessary to understand the cause of the cracking before developing a rehabilitation strategy. A consultant was hired to provide an analysis and detailed rehabilitation plans. Following an extensive engineering analysis, the cracking was determined to be a result of rocking (out-of-plane bending) at the floorbeam stiffeners caused by live load on the stringers (Figure 22 shows the locations). The stiffeners were originally installed as a tight fit to the top flange (tension flange). At the time this bridge was constructed, welding stiffeners to the tension flange was not a common practice. The stiffeners had a small gap between the stiffener and top flange allowing the flange to rotate, which induced fatigue cracks in the toe of the web-to-flange weld. To repair this, it was necessary to field weld the stiffeners to the top flange and grind out cracks in the weld toe of the web-to-flange fillet weld. A maximum depth of ¼ in. was allowed for grinding, and any locations not meeting this criteria required additional engineering analysis. Field welding consisted of fillet welding the stiffeners to the floorbeam top flange as shown in Figure 23. After fillet welds were completed, mechanical treatment (ultrasonic impact treatment) was performed on the toe of the fillet welds where the welds intersect the top flange to relieve tensile residual stress and apply a compressive residual stress on the surface to improve the fatigue life of the welds. Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details The DOT considered alternate repair details; however, given the extremely small movements that appeared to be the cause of the cracking, welding provided the most assurance in stop- FIGURE 22 Illinois DOT locations of field welding for out-of-plane cracking. FIGURE 23 Illinois DOT field weld details.
33 ping the out-of-plane top flange movement. A bolted retrofit may have been possible at some but not all locations as a result of congestion of other surrounding details. Slip critical bolted details might have worked; however, welding provided better assurance of stopping the very small movements. The repair was reported to be cost-effective, including both the welding and UIT. There were unique pay items for both; therefore, the as-bid prices could be provided. For access, temporary working platforms were suspended below the superstructure. Field Welding Staff Welders were required to be qualified for overhead position in accordance with AWS Bridge Welding Code D1.5:2008. In addition, the contractor field welding staff was required to perform a one-time, on-site, overhead fillet weld qualification test. The test plate was the fillet weld T-plate in accordance with AWS D1.5:2008 Clause 5.23.1.4. Visual inspection and fillet weld break tests were required. Qualification testing was performed by the contractorâs quality control CWI. Current Manual and Specification Detailed design drawings were developed from the engineer- ing analysis. Specifications for work were noted on the design drawing for field welding along with special provisions. Work was performed under stringent and detailed requirements. The contractor was required to submit WPSs, CWI qualifications, and NDT qualifications for approval before beginning work. It was necessary that all welders be tested to additional require- ments and approved before starting work. Work in the field required extensive cleaning prior to welding, including the removal of paint at least 3 in. beyond the weld zone; no sur- face rust was allowed and the blast surface needed to meet the requirements of SSPC-10. Continual monitoring by a qualified CWI was required for welding preheat, electrode control, and the welders. Contractor quality control CWI was required to perform visual inspection and NDT. Design Methodology and Preparation of Plans and Specifications Extensive engineering analysis was undertaken to determine the cause of the cracking on the top flange of the floor beams at the stringers. This involved evaluating locations where the stringers were continuous over the floor beams and locations where the stringers terminated at a floorbeam. This analysis included extensive field testing that involved strain gages, displacement sensors, tilt meters, and test trucks. From the field testing data, a three-dimensional global model was developed. In addition, a three-dimensional local model was created uti- lizing a single floorbeam and selected stringers. Rehabilitation design drawings were developed for the bridge that included partial removal and replacement of the deck and floorbeam brackets at the joints. For the floorbeam brackets that were not removed, a detailed design was devel- oped to perform field welding of the floorbeam stiffeners to the floorbeam top flange, which included material testing to determine the steel weldability. Welding Code Requirements All field welding was done in accordance with AWS Bridge Welding Code D1.5:2008, with additional requirements noted on the design plans. These additional requirements specified that all welding be performed with SMAW and that electrode storage and handling be in accordance with AWS, which required constant monitoring by the contractor quality con- trol CWI. Quality Assurance and Quality Control Inspection Requirements The contractor was required to provide full-time quality control by qualified CWI personnel for the field welding. Full-time visual inspection was required as work was performed. If the contractor worked at multiples locations, multiple CWIs were necessary. Quality assurance was the responsibility of the DOT engineer on site during the rehabilitation. Quality Control and Quality Assurance Submittals Table 3 is a summary of the quality control and quality assur- ance repair and inspection procedures and qualifications. Performance of Repairs and Retrofits Performance of Field Welds The DOT reports that the repair has performed well in ser- vice; no issues have been identified by follow-up inspec- tions. The agency would use field welding again in a similar situation. Effective Practices The DOT prefers to have all welding requirements clearly identified in the contract plans including, but not limited to, weld preparation, preheat, weld procedure, welder qualifica- tion, contractor QC requirements, QC staff qualification, and NDT requirements on all welds. Lessons Learned The DOT reported that it is not aware of anything that should be done differently on similar future projects.
34 CASE EXAMPLE 3âMAINE DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location Bridge #5995 carries I-95 northbound over Hinckley Road in Clinton, Maine. This bridge is a three-span, steel, multi-girder, rolled beam bridge composite with a cast-in-place deck, consisting of six beam lines. This bridge was built in 1964 and rehabilitated in 1994. Field Welding Details This case example involved the repair in fall 2008 of five of the six non-FCM rolled beam girders that were damaged when an aerial lift on a truck struck the bridge. The damage included gouges, cracks, and holes punched through the web by the diaphragms. In three of the beams, the dam- age required that a portion of the web and bottom flange be replaced by a âTâ piece with a partial joint penetration (PJP) weld on the web and a CJP weld on the flanges, as shown in Figure 24. This process involved the use of jack- ing on the damaged beams during the repair. A ceramic backing bar was used for the CJP weld on the flanges. The web was welded first with a double bevel groove weld before creating the weld-access holes for the flange CJP weld. The flange CJP welds were then performed and, after NDT was performed and accepted, the backup bars were removed and the weld was ground smooth. The new diaphragms were added and the necessary portions of the bridge were repainted. Submittals Y/N Comments Field Procedures Y Detailed procedures and design details provided on the design drawings Welder Qualification Y Required to be qualified to AASHTO/AWS D1.5 with additional on-site fillet weld test required Weld Procedure Y Formal WPS was required to be submitted and approved prior to Inspection Procedure Y Detailed procedures were specified on the design drawings that required full-time inspection. Visual Inspector Qualifications Y Qualified CWIs were required to be approved prior to performing work for all visual inspections per Clause 6 of the Bridge Welding Code. NDT Qualifications Y Qualified personnel were required to be approved before performing work in accordance with Clause 6 of the Bridge Welding Code. performing work. TABLE 3 ILLINOIS DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS FIGURE 24 Maine DOT CJP weld repair sketch.
35 Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details A bolted splice was considered; however, this type of repair would lower the vertical clearance by 2 in., which would increase the risk of this bridge getting hit again. The DOT likes to control the length of time that a repair is being performed to limit the impact to the public. In total, the repair took four weeks, with total costs controlled by using an in-house crew to fit-up and prepare the weld location. No road closures were required because the only disruption was the jack posts on either side of the repair. Field Welding Staff The field welding was contracted out to an experienced outside contractor that had been used previously on similar work. To help control costs, an in-house crew was used to fit-up and prepare the welding locations. Current Manual and Specifications Design Methodology and Preparation of Plans and Specifications The design for the field welded repair was done in-house and produced detailed design sketches and a repair plan, a portion of which is shown in Figure 24. The repair included step- by-step procedures for traffic control, repair implementation, and NDT requirements, along with jacking design plans, paint removal locations, and repair details. Previous field weld repair projects and experience was utilized in the development of the repair procedure and sketches. The weldability of the steel was determined based on the age of the bridge, which was constructed in 1964 and steel from this era tends to have reasonable weldability. WPS was developed for this project. Welding Code Requirements A mixture of AASHTO/AWS D1.5 and AWS D1.1 welding codes was used. Most of the requirements came from AWS D1.5; however, it was supplemented with some requirements from AWS D1.1. Quality Assurance and Quality Control Inspection Requirements The agency performed in-house visual inspection of all fit-up before welding for CJP and PJP welds. Magnetic particle test- ing was done in-house between weld layers on PJP welds and visual inspection was done throughout the repair process with qualified CWIs. Radiographic testing on the CJP welds was performed by a qualified outside contractor. Quality Control and Quality Assurance Submittals Table 4 contains a summary of the quality control and quality assurance repair and inspection procedures and qualifications. Performance of Repairs and Retrofits Performance of Field Welds The DOT reports that the repairs are performing well; their intention is to follow-up with a hands-on inspection to ensure that there are no issues. Routine inspections have been per- formed on the repair every two years and no issues were found. The repair was cost-effective and the agency would do it again. The welding cost was $8,000, steel $5,400, inspection $2,760; and the total cost including heat straightening was $155,000. Effective Practices Maine DOT endorses field welding and reports good success with field welded repairs. The most effective practices for field welding are: find the most efficient welder you can and provide the welder with large access holes; employ ceramic backers to aid the welder; use temporary web holders for tight fit-up (take off and place the bolt in hole later); employ a good experienced and enthusiastic crew, and use good equipment (jacking posts and beams). Lessons Learned The DOT reported that it is important to ensure that access holes are large enough for the welder. Submittals Y/N Comments Field Procedures Y On PJP welds, MT performed on each layer of weld with visual inspection at the completion of the weld. The CJP welds required RT. Welder Qualification Y Require appropriate qualifications Weld Procedure Y Welder and DOT worked together to develop the procedure Inspection Procedure Y In-house procedures Visual Inspector Qualifications Y DOT CWI NDT Qualifications Y Qualified in RT PJP = partial joint penetration. TABLE 4 MAINE DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS
36 CASE EXAMPLE 4âMASSACHUSETTS DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location Charles M. Braga Jr. Memorial Bridge carries I-195 over the Taunton River connecting Fall River, Massachusetts, with Somerset, Massachusetts. The bridge is 5,780 ft long, which includes a three-span continuous truss and two-girder approach spans. The three-span continuous truss, which includes FCMs, has 420-ft end spans with an 840-ft main span, the longest single span in Massachusetts. The two-girder approach spans consist of fracture critical riveted girders. Bridge construc- tion began in 1959 and was completed in 1966. The deck was replaced in the 1980s. Field Welding Details This case example involves an ongoing repair of corroded and buckled non-FCM stringer ends caused by leaking deck joints. Approximately 30% of the repairs were performed under a previous contract, which was terminated two and a half years ago, and a new contract put in place to finish the rehabilitation of the bridge. This contract covers fixing the deck joints, which leaked on the stringers and corroded the stringer ends caus- ing some of them to buckle. The repair involves the removal of the buckled end of the beams on the approach and main spans and replacement of the existing stringer end geometry with a WT section that has a CJP weld to the web and flanges, as shown in Figure 25. The stringers ends are cut after jacking with the top flange left in place. There are 16 stringers in the bridge cross section of the bridge, and approximately 130 to 150 stringer end locations require replacement. Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details The DOT has two repair details for the corroded stringer ends. If the web is buckled, the field welded repair is implemented. If the web is not buckled and only corroded, a bolted retrofit using sandwiched plates is performed. The deciding factor in determining whether to field weld was that the webs were already buckled and each new piece was to be custom fitted to match the geometry. It was noted that a bolted connection was never considered for the buckled locations because of the complexity of the geometry. Field Welding Staff The agency contracted out all repairs through a typical bid package. Current Manual and Specifications Design Methodology and Preparation of Plans and Specifications Massachusetts DOT contracted out the design for the field welded repair to a consultant. This design consultant devel- oped a bid package with contract documents for this repair. The contract drawings included repair steps and step-by-step procedures for jacking and shoring. The original base material was matched for replacement material. The DOT standard repair specification was utilized for this project and did not include any specific sections on field welding. The weldability of the steel was verified through material sampling. Base metal samples were taken to run bend, hardness, and chemi- cal testing. Carbon equivalent was also computed to verify weldability. This level of testing was more extensive than the typical material sampling tests that usually only include chem- ical testing. Welding Code Requirements Massachusetts DOT specified AASHTO/AWS D1.5 as the welding code for the field welding. Quality Assurance and Quality Control Inspection Requirements Massachusetts DOT repair welding was done in two phases. For the first phase of the repair, inspections were performed in-house with a qualified CWI. When a new contract was issued to complete the rehabilitation on the bridge, the contractor provided a CWI to perform visual inspection and an outside qualified agency performed 100% UT on the repair welds. The agency also supplied a CWI to spot check the work. Quality Control and Quality Assurance Submittals Table 5 contains a summary of the quality control and quality assurance repair and inspection procedures and qualifications.FIGURE 25 Massachusetts DOT stringer beam end repairs.
37 Performance of Repairs and Retrofits Performance of Field Weld The DOT started the repair of stringer ends in 2010 and con- tinued with repairs into 2011. The repairs are performing as expected and no issues have been noted. The repair was cost- effective; considerably less costly than replacing the entire stringer. Effective Practices Massachusetts DOT endorses field welding. A considerable amount of field welding is undertaken on a routine basis. The DOT intends to let another project to perform similar stringer end repairs as described in this case example. Its most effective practices for field welding are: use certified welders, have a CWI on-site, outline very clear requirements in the contract, and be as specific as possible. Lessons Learned The agency reports that it is very important to have correct details (plans) and specifications for a project. It stressed the need for all projects to have plans and specifications, especially the small projects. CASE EXAMPLE 5âTENNESSEE DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location This bridge carries Demonbreun Street over I-40 in downtown Nashville, Tennessee, and is a two-span, steel, multi-girder, welded plate girder bridge with span lengths of 102 and 112 ft. The bridge was built in 1969 and consists of 11 beam lines. Field Welding Details This case example involved the repair in 2001 of a non-FCM- welded plate girder, which was damaged by impact to the bridge. The damage resulted in two tears in the web at the diaphragms and required that portions of the web be replaced by CJP welds for the web-to-web splice and fillet welds for the web-to-flange welds. The flanges and web were heat straight- ened; next a 2-ft by 2-ft and a 3-ft by 4-ft section of the web was removed and replaced by welding new sections of the web and stiffeners. This bridge had previously been struck several times and was struck again in 2004 after the 2001 repair. After this hit, the fascia beam that was struck each time because the slope of the roadway below was redesigned with a shallower beam. Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details The DOT did not consider alternate repair details and went straight to field welding because this approach had previously been used on this bridge. During the 2001 repair, the replace- ment of the girder was evaluated as a result of it being hit repeatedly; however, this was not done at that time owing to the additional cost and because a traffic lane would have to be closed for too long. The beam was later replaced with a shal- lower beam in 2004 after being hit again. For the 2001 repair, the cost, timing, access, and complexity were considered and it was determined that field welding was the most effective repair method. Field welding can save time because the repairs were completed over two weekends when a lane could be closed. Field Welding Staff Tennessee DOT contracted out the welding because flux cored arc welding (FCAW) was performed. Current Manual and Specifications Design Methodology and Preparation of Plans and Specifications The agency designed the field welded repair in-house and created a set of construction plans and drawings. The AASHTO design specification was referenced, along with the specified AASHTO/AWS D1.5 welding code and an internal specifi- cation for heat straightening. The weldability of the steel was Submittals Y/N Comments Field Procedures Y The contract plans show the repair steps including procedures for jacking and shoring. Welder Qualification Y Submitted to the DOT for approval. Mass DOT has an internal welder qualification program that is required for all welders. Weld Procedure Y The contractor developed the weld procedure and it is approved by the DOT. Inspection Procedure Y Listed in the contract documents Visual Inspector Qualifications Y Outside contractor provided qualifications for DOT approval. NDT Qualifications Y Outside contractor provided qualifications for DOT approval. TABLE 5 MASSACHUSETTS DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS
38 determined by noting the material specification from the design drawing that showed that it was weldable steel from 1969. Most of the bridge is ASTM A36 steel, with one section of ASTM A441 Grade 50 steel that previously had been welded. Welding Code Requirements Tennessee DOT specified AASHTO/AWS D1.5 as the welding code required for field welding. Quality Assurance and Quality Control Inspection Requirements Tennessee DOT provided in-house inspectors who were deemed to be qualified owing to several years of experience, but were not necessarily AWS-certified CWI. Inspection was done on the weld preparation for fit-up. DOT inspectors were on site 100% of the time while weld repairs took place and per- formed visual inspection on the CJP and fillet welds. Ultrasonic testing was contracted out to a qualified contractor. Quality Control and Quality Assurance Submittals Table 6 contains a summary of the quality control and quality assurance repair and inspection procedures and qualifications. Performance of Repairs and Retrofits Performance of Field Weld Tennessee DOT reports that the 2001 repair has been replaced, but that it was in service for 3 years without any problems. This beam had been repaired several times since 1969, and no weld repairs had ever torn following subsequent hits. There were no issues reported for this repair and the agency stated that it was cost-effective. Effective Practices Tennessee DOT has performed multiple field repair welds and endorses the continued use of field welding. The agency has found that the most effective practices for field welding are: perform good inspection; require qualified welders with experience in bridge welding, especially if the welders come from a shop; and require written weld procedures. Lessons Learned Tennessee DOT noted the importance of ensuring that the contractor is experienced in field work. Some contractors may have been experienced in the shop, but not for field welding. The agency is planning on having a CWI on site at all times in place of in-house inspectors who cannot be there full time. The DOT stressed the importance of full-time observation of the welders. CASE EXAMPLE 6âTEXAS DEPARTMENT OF TRANSPORTATION Extent of Field Welding Bridge Type, Layout, and Location This bridge, built in 1978, carries SH-124 traffic over the Intra- coastal Waterway and is located 20 miles south of Winnie, Texas, or 50 miles northeast of Houston, Texas. The multi-span, steel, three-girder portion of the bridge is 690 ft long with a 290-ft center span. The total length of the bridge including approach spans is 4,300 ft. Because the three-girder portion of the bridge has a 20-foot spacing between girders, these gird- ers are considered to be FCM in accordance with Texas DOT requirements (spacing of 20 ft or more for three-girder bridges). Field Welding Details This case example involves December 2013 repair of a FCM girder that was damaged by impact on the bottom flange from a crane on a vessel that struck the bottom flange of the bridge. This bridge is the primary access for residents of the Bolivar Peninsula to mainland Texas. The damage caused cracking in the bottom flange and stiffener, and required that portions of the fillet welds be gouged out and rewelded with new fillet welds. Consideration of Cost, Timing, Access, Complexity, and Alternate Repair Details Texas DOT went directly to a field weld repair because the damage was not stress-induced or caused by fatigue. The Submittals Y/N Comments Field Procedures Y Contractor submitted a heat straightening plan (general procedures) and weld procedures. Welder Qualification Y AASHTO/AWS D1.5 Bridge Welding Code Weld Procedure Y AWS D1.5 Inspection Procedure Y AASHTO/AWS D1.5 for visual and UT Visual Inspector Qualifications Y In-house inspectors internally qualified, not necessarily a CWI NDT Qualifications Y Verified by the DOT TABLE 6 TENNESSEE DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS
39 repair was simple because the cracked fillet weld only had to be gouged out and rewelded. This type of repair was cost- effective because it did not require a bid package and was performed in-house. Field Welding Staff The DOT performed the field welding in-house; however, they typically will contract out most of their field welding. Over time, less of their field welding has been performed in- house rather than contracted out. Current Manual and Specifications Design Methodology and Preparation of Plans and Specifications The DOT reported that this repair approach was more casual than usual owing to the urgency of the repair because this bridge is the primary access to the Bolivar Peninsula. No specific retro- fit details or drawings were developed before the repair was performed, which is unusual for TxDOT. The agency typically designs most repairs in-house and is strict about developing project-specific details and specification; however, the TxDOT standard specification was used on the example project, which includes a section on welding and welding requirements. AASHTO/AWS D1.5 welding code was specified and relied on for additional welding requirements. The weldability of the steel was determined based on the age of the bridge and weld- ing previously performed on the bridge. The steel for this bridge was ASTM A588 weathering steel from 1978. Welding Code Requirements TxDOT specified AASHTO/AWS D1.5 as the welding code for field welding and also referenced Item 448 of its internal standard specification, which covers structural field welding. Quality Assurance and Quality Control Inspection Requirements The DOT often replaces a segment of a girder where impact damage has taken place. The CJP welds were 100% radio- graphic tested by a qualified firm. For the CJP welds and fillet welds, a qualified CWI performed visual inspection. Quality Control and Quality Assurance Submittals Table 7 is a summary of the quality control and quality assur- ance repair and inspection procedures and qualifications. Performance of Repairs and Retrofits Performance of Field Weld TxDOT reports that the repair performed in-service with very good results. The repair was located at mid-span, in the main span, but was not the result of a stress-induced crack. There have been no issues noted in follow-up inspections. The repair was as cost-effective as possible and took only a few hours. Effective Practices TxDOT endorses field repair welding, and field welding is used often on its projects. Their most effective practices for field welding include a welder certification program, because every welder employed by TxDOT must be certified through this program. The DOT emphasized enforcing and adhering to the program. It is not sufficient to simply specify a code or specification, the agency requires the presence of an expert CWI on site, full time while work is being performed. Lessons Learned The DOT noted that nothing would be different other than monitor gouging out a weld and rewelding more closely. SUMMARY The six case examples discussed a variety of the types of field welded repairs that can be performed in the field. Included were repairs for impact damage, corrosion, and out-of-plane bending. Each of the agencies interviewed reported a positive outcome from the field welded repair and plan to continue to utilize field welded repairs on future work. They reported that Submittals Y/N Comments Field Procedures Y No, not in this case. Normally requires contractor to show their intentions in step-by-step procedures, but do not require a formal WPS for field welding. Welder Qualification Y All welders must be certified by the DOT program. Weld Procedure N For this project onlyâWPSs required on all other projects. Inspection Procedure Y Not on this project, normally require a procedure. Visual Inspector Qualifications Y In-house CWI was used; TxDOT does in-house quality control for field welding with four CWIs on staff. NDT Qualifications Y UT was performed in-house, RT is contracted out. TABLE 7 TEXAS DOT QUALITY CONTROL AND QUALITY ASSURANCE SUBMITTALS
40 there were no follow-up problems with the field welded repairs and the repairs were reported to be cost-effective. ⢠Connecticut DOT does a significant amount of field welding and endorses it as a repair method. ⢠Illinois DOT stressed the importance of clearly iden- tifying all welding requirements in the contract plans. ⢠Maine DOT endorses field welding and reports good success with field welded repairs. ⢠Massachusetts DOT endorses field repair welding and reports that its most effective practices for field welding are the use of certified welders, use of approved weld- ing procedures, having a CWI on site, and having very clear and specific requirements in the contract. ⢠Tennessee DOT has previously undertaken multiple field repair welds and endorses its continued use. The agency has found that the most effective practices for field welding are efficient inspections, requiring qualified welders with experience in bridge welding, and requiring written weld procedures. ⢠TxDOT endorses field repair welding, and it is often used on its projects. It reported that the most effective prac- tices for field welding include its welder certification program, because every welder who works for TxDOT must be certified through this program. The agency also emphasized the importance of having an expert CWI on site full time while work is being performed. Similar points of emphasis were reported by the agencies when asked what was important in achieving a positive out- come to a field welded repair or retrofit. When asked to share some lessons learned, the agencies suggested a variety of items they either corrected, would do differently, or would not change on future projects. ⢠Illinois, Connecticut, and Texas DOTs stated that they would do nothing different. ⢠Massachusetts DOT emphasized the importance of correct details and specifications. ⢠Maine DOT reiterated the importance of good weld access holes for the welder. ⢠Tennessee DOT stressed the importance of hiring a contractor who was experienced in field welding and the importance of qualified inspectors.
