trail bridge inspection and condition assessment module 3 bridge

Download trail bridge inspection and condition assessment module 3 bridge

Post on 03-Jan-2017

218 views

Category:

Documents

4 download

Embed Size (px)

TRANSCRIPT

  • TRAIL BRIDGE INSPECTION

    BRIDGE INSPECTION PROCEDURES

  • Objectives:Learn the different inspection methodsLearn a standard procedure to conduct routine bridge inspectionLearn what to look for during an inspection

  • Bridges Inspection MethodsThere are three basic methods used to inspect a timber bridge.

    They include:

    VisualPhysicalAdvanced inspection techniques

  • Visual InspectionsFor timber members, visual inspections reveal areas that need further investigation such as checks, splits, shakes, fungus decay, deflection, or loose fasteners.

    *For timber members, visual inspections reveal areas that need further investigation such as checks, splits, shakes, fungus decay, deflection, or loose fasteners.

  • Types of Visual InspectionsCursory Inspection

    Involves reviewing the previous inspection report and visually examining the membersInvolves a visual assessment to identify obvious defectsHands-on Inspection.

    Requires the inspector to visually assess all defective timber surfaces at a distance no further than an arms lengthTimber surfaces are given close visual attention to quantify and qualify any defects.

    *There are two types of visual inspections that may be required of an inspector.

    The first, called a cursory inspection, involves reviewing the previous inspection report and visually examining the members from beneath the bridge. A cursory inspection involves a visual assessment to identify obvious defects.

    The second type of visual inspection is called a hands-on inspection. This type of visual inspection requires the inspector to visually assess all defective timber surfaces at a distance no further than an arms length. The timber surfaces are given close visual attention to quantify and qualify any defects.

    For timber members, visual inspections reveal areas that need further investigation such as checks, splits, shakes, fungus decay, deflection, or loose fasteners.

  • Physical ExaminationOnce the defects are identified visuallyPhysical procedures are then used to find out the extent of the deterioration or decay

    The basic methods for physical examination are:

    Pick TestSounding

    *Physical ExaminationOnce the defects are identified visually, physical procedures must be used to verify the extent of the defect. Most physical inspection procedures for timber members involve destructive methods. An inspection hammer, on the other hand, does not and can be used to tap on areas and determine the extent of internal decay. This is done by listening to the sound the hammer makes. If it sounds hollow, internal decay may be present. Some methods or areas of physical examination include:

  • Pick TestProbing with a pointed tool such as an awl will locate decay near the wood surface.

    Decay will be evidenced by excessive softness or lack of resistance to the probe penetration and the breakage pattern of the splinters.

    A brash break indicates decayed wood, whereas a crisp splintered break with the splinter hinging from one end indicates sound wood.

    *Pick or Penetration TestA pick or penetration test involves lifting a small sliver of wood with a pick or pocketknife and observing whether or not it splinters or breaks abruptly. Sound wood splinters, while decayed wood breaks abruptly.

    Probing with a pointed tool such as an awl will locate decay near the wood surface. Decay will be evidenced by excessive softness or lack of resistance to the probe penetration and the breakage pattern of the splinters.

    A brash break (straight line break directly above and parallel with the axis of the awl) indicates decayed wood, whereas a crisp splintered break with the splinter hinging from one end indicates sound wood.

    However, care must be taken to differentiate between decay and water-softened wood.

  • Pick TestDecayed wood breaks abruptly across grain without splintering.Sound wood pries out as long splinters.

    *

  • SoundingSounding the surface by striking it with a hammer is one of the oldest and most commonly used inspection methods.

    Although sounding is widely used, interpretation is VERY subjective.

    Soundings are based on the tonal quality of the ensuing sounds and the rebound of the hammer

    Practical experience has shown that sounding is only useful for members less than 4 inches thick.

    *Sounding the surface by striking it with a hammer is one of the oldest and most commonly used inspection methods.

    Although sounding is widely used, interpretation is VERY subjective.

    Soundings are based on the tonal quality of the ensuing sounds and the rebound of the hammer Practical experience has shown that sounding is only useful for members less than 4 inches thick.

  • SoundingInterpreting Soundings:Sound timber gives a crisp sound. Defective timber gives a dull sound.Loose hardware will vibrate.

    Note: A 2 inch thick shellof competent wood is sufficient to maskany interior rot.

  • Advanced Inspection TechniquesOther types of advanced inspection techniques are:

    Coring and DrillingResistograph DrillStress Wave MeterMoisture Meter

    These techniques are beyond the scope of this training course.

    *Advanced Inspection Techniques

    In addition, several advanced techniques are available for timber inspection. Nondestructive methods include:Stress wave meterResistographMoisture meter

    Other methods, described include:Boring or drillingMoisture contentProbingShigometer

    Detailed information about timber bridges can be found from the text, Timber Bridges, Design, Construction, Inspection and Maintenance, published by the USDA Forest Service. Latest information about timber bridge technology, including publications, can be obtained from the Forest Services Timber Bridge Information Resource Center at (304) 285-1591 or at the website at http://www.fs.fed.us/. Information can also be obtained at the FHWA website, which is at TFHRC.dot.gov.

  • General Bridge Inspection ProceduresThe bridge inspection procedure should be completed by the numbers.

    Which means the bridge is inspected in a methodical way from either top to bottom or bottom to top.

    It is important to document the inspection.

    *Cursory InspectionInvolves reviewing the previous inspection report and visually examining the membersInvolves a visual assessment to identify obvious defectsHands-on Inspection. Requires the inspector to visually assess all defective timber surfaces at a distance no further than an arms lengthTimber surfaces are given close visual attention to quantify and qualify any defects.

  • General Bridge Inspection ProceduresDocumentation should include:An inspection report and notesAnd lots of photographs

    Photographs should be a minimum of 10 pictures with additional pictures of problem areas.

    *

  • General Bridge Inspection ProceduresMinimum required photographs:Near approach looking at the bridgeFar approach looking at the bridgeBridge deck and railingUnderside of the deck and beamsUpstream looking downstream at the bridgeDownstream looking upstream at the bridgeLooking upstream from the bridgeLooking downstream from the bridgeNear side substructureFar side substructure

    *

  • Near and far approaches looking at the bridge

  • Bridge Deck and Railing

  • Underside of Deck and Beams

  • Looking upstream and downstream from the bridge deck

  • Looking upstream and downstream at the bridge

  • Looking at right and left abutments

  • Additional Photos

    Anything that needs to be noted or watched.

  • Starting an InspectionFirst conduct a cursory visual inspection of the entire bridge looking for indications of problems.

    *

  • Cursory Visual InspectionLook for:Sagging or twisted beamsHanging or broken beamsPounding waterSettlement

    *

  • Next, conduct a hands-on visual inspection of the bridge parts taking into account any indications of problem found during the cursory inspection.

    During the hands-on visual inspection, the inspector should look for signs of deterioration or decay that will require a physical examination.

    *

  • Where to look for decay?

    *

  • Where to look for decay?Around ChecksAround SplitsAround ShakesAround CracksAround FastenersAreas in contact with soilAreas where debris and water collect

    *

  • Conduct the inspection

    BY THE NUMBERS

    Start at the top of the bridge and work your way down the load paths. This will help you from missing any parts of the structure.

    *

  • One Inspection order could be:Railings/curbsDecking (Planks)Superstructure (Beams, Stringers)Substructure (Abutments, Sills)ChannelApproachesSignage

    *

  • General Bridge Inspection Procedures1) Inspection of railings/curbingThings to looking for?Missing rails, posts, curbs or hardwareBroken rails, posts or curbsDeteriorated (rotten) rails, posts or curbs

    *

  • 1) Inspection of railings/curbingMissing rails, posts, curbs or hardware

    *

  • 1) Inspection of railings/curbingBroken rails, posts or curbs

    *

  • 1) Inspection of railings/curbingDeteriorated (rotten) rails, posts or curbs

    *

  • General Bridge Inspection Procedures2) Inspection of deckingThings to looking for?Missing planks or hardwareBroken planks or hardwareDeteriorated (rotten) planksWear of the deckDebris on deck

    *

  • 2) Inspection of deckingMissing planks or hardware

    *

  • 2) Inspection of deckingBroken planks or hardware

    *

  • 2) Inspection of deckingDeteriorated (rotten) planks

    *

Recommended

View more >