Last edited by Dobei
Thursday, February 6, 2020 | History

4 edition of Heat-straightening repairs of damaged steel bridges found in the catalog.

Heat-straightening repairs of damaged steel bridges

Heat-straightening repairs of damaged steel bridges

a technical guide and manual of practice

by

  • 86 Want to read
  • 36 Currently reading

Published by U.S. Dept. of Transportation, Federal Highway Administration in [Washington, D.C.] .
Written in English

    Subjects:
  • Bridges -- Maintenance and repair -- Handbooks, manuals, etc,
  • Bridges, Iron and steel -- Maintenance and repair -- Handbooks, manuals, etc

  • Edition Notes

    Statementprepared by Structural Damage Control, Inc. ; prepared for Bridge Office, Office of Infrastructure, Federal Highway Administration ; [authors: R. Richard Avent, David Mukai].
    GenreHandbooks, manuals, etc.
    ContributionsMukai, David J., United States. Federal Highway Administration. Office of Bridge Technology., Structural Damage Control, Inc.
    The Physical Object
    FormatMicroform
    Paginationxix, 248 p.
    Number of Pages248
    ID Numbers
    Open LibraryOL17604937M
    OCLC/WorldCa49730650

    During proper repairs, the repeated heating and cooling of the damaged area will move the member back to it's original shape. Chapter 7 provides technical information on damaged composite beams and proper methods to repair them. However, these positive strains are small in comparison to the simultaneous shortening of the bottom edge of the plate. As the steel cools, it contracts and returns to its original shape.

    Chapter 3 describes methods of assessing, planning and conducting successful repairs along with common mistakes to avoid. Why did they draw false correlations between their distorted perceptions of the former with their own limited vision of intelligence? The experience of the practitioner is the most reliable guide to proper sequencing. The limit approximately defines the delineation between the plastic region and the strain-hardening region. Because the bulge has been heated, its yield value has been lowered, resulting in plastic deformations, which do R.

    The most significant changes occurred in ductility, which was typically reduced by one-third. Of particular interest is the degree to which the material has been strained past yield. Similarly high values were found at the heels and toes of channels Figure At this point the plate has moved downward Figure 3b due to longitudinal expansion of material below the neutral axis, producing positive bending.


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Heat-straightening repairs of damaged steel bridges book

When a combination of vee, strip or line heats is used, the order of heating is referred to as the sequence. The most significant changes occurred in ductility, which was typically reduced by one-third.

The manual is designed to be used in conjunction with a multimedia instructional computer program and video produced as part of this project. Revisions and errata are included in Appendix.

Financially, heat straightening is less costly than repairs involving replacement for several reasons. Only by carefully controlling the amount and location of the heat and restraining forces can true heat straightening repairs be accomplished.

A second alternative with similar effect is shown in Figure 5b using a single torch and starting from one side. This is known as mechanical or "hot" working.

The usual explanation is that small microcracks must have occurred as a result of initial damage. For web bulges either lines or vees may be used. Past research was conducted in the context of heat curving not heat straighteningand thus is somewhat limited in its applicability to heat straightening.

For Category S damaged wide flange beams, the pattern reversed with compression stresses in both flanges and tension in the web, as shown in Figure Early ironworkers and welders discovered that when heat was applied to small areas of a steel member, the member was distorted.

When in doubt, a good policy is to address one of the fundamental damage patterns at a time. The report will be of particular interest to engineers in state highway agencies and industry responsible for bridge maintenance and repair. During cooling this side consequently contracts more, creating a concave bend on the torch side of the plate similar to that shown in Figure 4d.

Part II is a technical guide to heat straightening directed primarily to engineers. However, more complex damage can be repaired by sequentially using the heating patterns for these four fundamental damage patterns.

The three basic types most often used in heat straightening are described as follows. Based on anecdotal evidence even larger strains can probably be repaired. Chapter 3 describes methods of assessing, planning and conducting successful repairs along with common mistakes to avoid.

These questions have been prompted by situ- ations in which field-repaired girders subsequently fractured. However, partial depth vees are used on the flange with the bulge along with a series of line heats along bulge yield lines.

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Under these circumstances, a hard, strong and brittle phase called martensite occurs. Of more significance are the properties of damaged plates or rolled shapes after experiencing the large number of heats required to fully straighten the member.

When a steel member is heated, the heated area expands. It is known that cold bending into the yield range reduces the ductility of steel in general Fig. The research team designed and conducted a major program of large-scale laboratory experiments to accomplish these tasks.

Heating pattern and sequence for combination weak axis bending and local flange bulge. The strip heat may be initiated at the midpoint and moved toward both edges simultaneously using two torches.

As a second example, consider a wide flange beam with weak axis bending damage combined with a local bulge in one flange.What You Should Know About Heat Straightening Repair of Damaged Steel R. RICHARD AVENT and DAVID J.

MUKAI INTRODUCTION T he repair of damaged steel through the application of heat has long been considered an art rather than a science. Although heat‐straightening has been used for the repair of damaged steel structures for over 40 yr, the process is more of an art than a science. Since the effects of heat‐straightening steel structures are not well understood by the engineering community, a number of undocumented opinions have appeared in the literature that are false or.

Members” of the component specified when measured by each member, or for “Repairing Steel Bridge Members” when measured by lump sum. This price is full compensation for repairing steel bridge members and for steel, grout, epoxy, materials, equipment, labor, tools, and incidentals.

determination of whether damaged bridge components should be repaired or replaced is made. COMMON REPAIRS. The most common steel repairs are: ADDING METAL TO STRENGTHENcross sections that have been reduced by corrosion or external forces.

WELDING OR ADDING COVERPLATES-to repair structural steel cracks caused. Heat-Straightening Repairs of Damaged Steel Bridges - Scholar's Choice Edition [D Federal Highway Administration (FHWA)] on atlasbowling.com *FREE* shipping on qualifying offers. This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it.

This work was reproduced from the original artifact. Heat Straightening Repairs of Damaged Steel Bridges—A Technical Guide and Manual of Practice. Federal Highway Administration, Washington DC, USA, OctoberReport No.

FHWA-IF