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Preventing Cracking At Diaphragm Plate Girder Connections In Steel Bridges
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Book Synopsis Preventing Cracking at Diaphragm/plate Girder Connections in Steel Bridges by :
Download or read book Preventing Cracking at Diaphragm/plate Girder Connections in Steel Bridges written by and published by . This book was released on 1998 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some of the Iowa Department of Transportation (Iowa DOT) continuous, steel, welded plate girder bridges have developed web cracking in the negative moment regions at the diaphragm connection plates. The cracks are due to out-of-plane bending of the web near the top flange of the girder. The out-of-plane bending occurs in the "web-gap", which is the portion of the girder web between (1) the top of the fillet welds attaching the diaphragm connection plate to the web and (2) the fillet welds attaching the flange to the web. A literature search indicated that four retrofit techniques have been suggested by other researchers to prevent or control this type of cracking. To eliminate the problem in new bridges, AASHTO specifications require a positive attachment between the connection plate and the top (tension) flange. Applying this requirement to existing bridges is expensive and difficult. The Iowa DOT has relied primarily on the hole-drilling technique to prevent crack extension once cracking has occurred; however, the literature indicates that hole-drilling alone may not be entirely effective in preventing crack extension. The objective of this research was to investigate experimentally a method proposed by the Iowa DOT to prevent cracking at the diaphragm/plate girder connection in steel bridges with X-type or K-type diaphragms. The method consists of loosening the bolts at some connections between the diaphragm diagonals and the connection plates. The investigation included selecting and testing five bridges: three with X-type diaphragms and two with K-type diaphragms. During 1996 and 1997, these bridges were instrumented using strain gages and displacement transducers to obtain the response at various locations before and after implementing the method. Bridges were subjected to loaded test trucks traveling in different lanes with speeds varying from crawl speed to 65 mph (104 km/h) to determine the effectiveness of the proposed method. The results of the study show that the effect of out-of-plane loading was confined to widths of approximately 4 in. (100 mm) on either side of the connection plates. Further, they demonstrate that the stresses in gaps with drilled holes were higher than those in gaps without cracks, implying that the drilling hole technique is not sufficient to prevent crack extension. The behavior of the web gaps in X-type diaphragm bridges was greatly enhanced by the proposed method as the stress range and out-of-plane distortion were reduced by at least 42% at the exterior girders. For bridges with K-type diaphragms, a similar trend was obtained. However, the stress range increased in one of the web gaps after implementing the proposed method. Other design aspects (wind, stability of compression flange, and lateral distribution of loads) must be considered when deciding whether to adopt the proposed method. Considering the results of this investigation, the proposed method can be implemented for X-type diaphragm bridges. Further research is recommended for K-type diaphragm bridges
Book Synopsis Deformation Induced Cracking in Steel Girder Bridges and Retrofit Guidelines by :
Download or read book Deformation Induced Cracking in Steel Girder Bridges and Retrofit Guidelines written by and published by . This book was released on 1987 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Heat-straightening Repair of Damaged Steel Bridge Girders by : Robert J. Connor
Download or read book Heat-straightening Repair of Damaged Steel Bridge Girders written by Robert J. Connor and published by Transportation Research Board. This book was released on 2008 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB¿s National Cooperative Highway Research Program (NCHRP) Report 604: Heat-Straightening Repair of Damaged Steel Bridge Girders: 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-straightening procedure.
Book Synopsis Fatigue cracking at cross beam connections in steel plate girder bridges by : Keizo Otsuka
Download or read book Fatigue cracking at cross beam connections in steel plate girder bridges written by Keizo Otsuka and published by . This book was released on 1995 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Distortion-induced Fatigue Cracking in Steel Bridges by : John W. Fisher
Download or read book Distortion-induced Fatigue Cracking in Steel Bridges written by John W. Fisher and published by Transportation Research Board. This book was released on 1990 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Cross-frame Diaphragm Bracing of Steel Bridge Girders by : W. M. Kim Roddis
Download or read book Cross-frame Diaphragm Bracing of Steel Bridge Girders written by W. M. Kim Roddis and published by . This book was released on 2008 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Steel plate girder bridges make use of traditional cross-frame diaphragms to stabilize the compression flange of girders. These braces are required during construction, especially during deck placement, to prevent lateral torsional buckling of bridge girders. Girder buckling capacity is a function of cross-frame diaphragm spacing as well as strength and stiffness. Recent developments in bridge design may cause the governing girder limit state to shift from one of strength to one of stability. These developments include the elimination of in-plan bracing, composite girders, High Performance Steels, and phased deck replacements. In addition, the American Association of State Highway and Transportation Officials (AASHTO) has changed its code requirement for cross-frame diaphragm spacing in the 1998 AASHTO LRFD Bridge Design Specifications. The requirement for 25-foot maximum brace spacing has been removed. The current requirement is for a "rational analysis" to determine cross-frame diaphragm spacing. Explanations of the problems these changes cause in design are discussed. A case study is presented of a bridge that suffered construction difficulties during deck placement. This investigation found that the cross-frame diaphragms were not stiff enough to brace the plate girders during the deck placement. Suggestions are given as to an efficient, economical design and spacing for cross-frame diaphragms on plate girder bridges.
Book Synopsis A Survey of Localized Cracking in Steel Bridges, 1981 to 1988 by : Cornelia E. Demers
Download or read book A Survey of Localized Cracking in Steel Bridges, 1981 to 1988 written by Cornelia E. Demers and published by . This book was released on 1989 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Influence of Secondary Components on the Serviceability of Steel Girder Highway Bridges by : Mohamed Abdel-Azim Elewa
Download or read book Influence of Secondary Components on the Serviceability of Steel Girder Highway Bridges written by Mohamed Abdel-Azim Elewa and published by . This book was released on 2004 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Retrofit of Cracked Welded Steel Bridge Girders by : JJ. Pullaro
Download or read book Retrofit of Cracked Welded Steel Bridge Girders written by JJ. Pullaro and published by . This book was released on 1990 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: A welded plate girder bridge on a main interstate highway in service for over 25 years suddenly develops a through crack in the web and flange of a fascia girder. An in-depth inspection and metallographic examination reveal the crack started in the vicinity of a welded diaphragm. The crack propagated quickly and was characteristic of a brittle fracture. Further analysis, including strain gauging and Charpy V-notch (CVN) tests, does not conclusively identify the cause for the propagation of the crack.
Book Synopsis Diaphragm Bolt Loosening Retrofit for Web Gap Fatigue Cracking in Steel Girder Bridges by : David Joseph Tarries
Download or read book Diaphragm Bolt Loosening Retrofit for Web Gap Fatigue Cracking in Steel Girder Bridges written by David Joseph Tarries and published by . This book was released on 2002 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many of Iowa's multiple steel girder bridges have shown signs of fatigue cracking due to out-of-plane deflection of the girder web near diaphragm connections. This fatigue prone web gap area is located in the negative moment regions of the girders where the stiffeners with diaphragms are not attached to the top flange of the girders. The Iowa Department of Transportation (Iowa DOT) has attempted to stop fatigue crack propagation but with limited success. For this reason the Iowa DOT has requested research on a new field retrofit to loosen the bolts in the connection between the diaphragm and the girders. The intent of this research is to show that loosening the bolts at the diaphragm/girder connections in steel girder bridges is effective in reducing strain and fatigue in the web gap. Select web gaps in negative moment regions on three heavily traveled bridges were instrumented with strain gages and deflection transducers to measure changes in the web gap due to the retrofit. Each bridge had a different diaphragm type: I-beam, channel, and X-brace. Field tests, using loaded trucks of known weight and configuration, were conducted on the bridge before and after implementing the bolt loosening retrofit. Short-term retrofit testing was conducted in the I-beam and channel diaphragm bridges. A long-term continuous monitoring test was completed on the X-braced bridge. Data was collected over a number of months with ambient truck traffic crossing the bridge. Data of significant load was recorded for analysis to support that the results of loosening the bolts do not change over time. Results indicate that loosening the diaphragm bolts reduces out-of-plane deflection and strain in the web gaps, as well as almost completely eliminating the strain in the diaphragms between the girders. The reduction in strain correlates to a reduction if not an elimination of fatigue cracking in the web gaps and an increase of in-service life of the bridge.
Book Synopsis Retrofit Methods for Distortion Cracking Problems in Plate Girder Bridges by :
Download or read book Retrofit Methods for Distortion Cracking Problems in Plate Girder Bridges written by and published by . This book was released on 2003 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The intent of this research is to study the short-term effects of the bolt loosening retrofit on I-beam and channel diaphragm bridges. The research also addressed the development of a continuous remote monitoring system to investigate the bolt loosening retrofit on an X-type diaphragm bridge over a number of months, ensuring that the measured strain and displacement reductions are not affected by time and continuous traffic loading on the bridge. The testing for the first three investigations is based on instrumentation of web gaps in a negative moment region on Iowa Department of Transportation bridges with I-beam, channel, and X-type diaphragms. One bridge of each type was instrumented with strain gages and deflection transducers. Field tests, using loaded trucks of known weight and configuration, were conducted on the bridges with the bolts in the tight condition and after implementing the bolt loosening retrofit to measure the effects of loosening the diaphragm bolts.
Book Synopsis Fatigue of Curved Steel Bridge Elements by : J. Hartley Daniels
Download or read book Fatigue of Curved Steel Bridge Elements written by J. Hartley Daniels and published by . This book was released on 1980 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Improving Infrastructure Sustainability by : Say Hak Bun
Download or read book Improving Infrastructure Sustainability written by Say Hak Bun and published by . This book was released on 2016 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distortion-induced fatigue affects a large number of bridges within the US highway system. This type of damage is commonly observed at connections between cross frames and steel girders. The differential displacement induced by bridge traffic induces forces in the cross frames that cause out-of-plane distortion of the web, inducing highly localized stresses at the welds that tie the connection plate used to attach the cross frame to the girder. This report describes the results of an experimental program to evaluate the use of composite materials to prevent and repair distortion-induced fatigue damage in web-gap regions of steel girders. In this method of repair, a composite block is cast in place in the area surrounding the cross frame-to-girder connection to provide an alternate load path and reduce the stress demands in the welds of the connection. Two full-depth bridge girders were subjected to dynamic loading under a constant force range and allowed to develop fatigue cracks. The girders were subsequently repaired using composite blocks and subjected to several million fatigue cycles. Test results showed that the repair method was effective in halting the propagation of fatigue cracks in the bridge girders, and that it was particularly effective when anchor bolts were attached to the girder flange.
Book Synopsis Aspects in Nondestructive Evaluation of Steel Plate Girder Bridges by : Ayman Hussein Hosny Khalil
Download or read book Aspects in Nondestructive Evaluation of Steel Plate Girder Bridges written by Ayman Hussein Hosny Khalil and published by . This book was released on 1998 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Additionally, the effects of two types of cracking were examined theoretically. The results indicate that while frequencies of vibration are global parameters, mode shapes are local parameters with the mode shape changes being more sensitive to damage than frequency shifts. Both mode shapes and frequencies of vibrations are capable of detecting major damage to the bridge structure.
Book Synopsis Field Tests of Distortion-induced Fatigue Cracking in Diaphragm-girder Connections for Multi-girder Bridges by : David Allen Lower
Download or read book Field Tests of Distortion-induced Fatigue Cracking in Diaphragm-girder Connections for Multi-girder Bridges written by David Allen Lower and published by . This book was released on 1995 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Improving Infrastructure Sustainability by : Hao Liu
Download or read book Improving Infrastructure Sustainability written by Hao Liu and published by . This book was released on 2016 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drilling crack-arrest holes to halt fatigue crack propagation is a simple technique that is commonly used by bridge owners controlling and/or repairing fatigue cracking in steel bridges. Well-established relationships exist for sizing the diameter of the crack-arrest holes for in-plane fatigue loading; however, the effectiveness of crack-arrest holes under out-of-plane (distortion-induced) fatigue is not well understood. Distortion-induced fatigue cracking is much more common in steel bridge infrastructure than in-plane fatigue cracking, and bridge owners often utilize drilled crack-arrest holes in these cases as a "first response" against fatigue cracks discovered during inspections. The purpose of the crack-arrest hole is to smooth out the sharp crack tip, reducing the stress concentration and halting/delaying crack propagation. Common knowledge has been that large diameter crack-arrest holes are more effective at halting crack propagation under distortion-induced fatigue than small diameter crack-arrest holes. However, drilling large diameter crack-arrest holes can have strength implications for a structure, and may not be desirable. Additionally, there is little evidence in the literature that large diameter crack-arrest holes perform better than small diameter crack-arrest holes under distortion-induced fatigue. A study examining the effectiveness of crack-arrest holes of varying diameters under distortion-induced fatigue loading was performed. The investigation was comprised of both experimental and analytical components. The experimental study was performed on segments of plate girder loaded under distortion-induced fatigue. Crack-arrest holes of various diameters were drilled at the tips of the cracks of different lengths, and their effectiveness was evaluated. A suite of three-dimensional, solid-element finite element analyses was also used to parametrically vary crack-arrest hole diameter, placement, and crack length. The study also included an analytical examination of using pretensioned bolts and plate washers in a crack-arrest hole. Limited effectiveness was noted for this technique, so the majority of the research focused on appropriate crack-arrest hole sizing and placement. The findings from the experimental and analytical components of this study were compared against common industry practices. The results show that crack-arrest hole placement, rather than hole diameter, has a much greater effect on the effectiveness of the crack-arrest hole in bridge girders susceptible to distortion-induced fatigue.
Book Synopsis Distortion-induced Fatigue Cracking of Girder-to-crossbeam Connection by : Dhari S. Aljutaili
Download or read book Distortion-induced Fatigue Cracking of Girder-to-crossbeam Connection written by Dhari S. Aljutaili and published by . This book was released on 2008 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oregon Department of Transportation's bridge no. 9743b is a multi-span, two-girder steel deck bridge connecting the busy interstates 5 and 205. Vertical cracks have been detected in the welded girder-to-crossbeam connections at the bents. Distortion-induced fatigue is suspected to be responsible for the cracking. Linear elastic beam analysis, 2-D and 3-D finite element analyses, and fatigue analysis were performed to determine the fatigue life of the connection based on highway moving loads and actual truck traffic data. Results of the analyses are discussed, and insight about the possible causes of distortion-induced fatigue cracking is presented. In conclusion, the live truck loading is ruled out as the cause, and the problem is narrowed down to the thermal loads.
