Nhi Nstm Study Guide Exam and All
Correct Answers.
Silver Bridge 1967 - Answer eye bar chain suspension bridge, unstable internal crack in eye
bar, bridge not maintained well, research began on redundancy, fatigue and failure from this,
NBIS
Mianus River Bridge - Answer pin and hanger was cracked and worsened due to fatigue, pin
separated from hanger, FHWA published " inspection of fracture critical bridge members
Daniel W. Hoan Memorial Bridge - Answer triaxial constraint ending in brittle fracture, two
main girders were completely severed because of a gusset plate and transverse connection
plate
I 35W Bridge - Answer gusset plates were half the thickness they were supposed to be,
bowing was shown
Sherman Minton Bridge - Answer fabrication flaw, cracks in one of the tie girders dating back
to original construction, T-1 steel, which is susceptible to hydrogen induced cracking
I-5 Skagit River Bridge - Answer Semi trailer over loaded directly hit multiple sway struts, not
considered NSTM, but makes inspectors aware of other components that can cause failure,
truck was not in the correct lane
I-276 Delaware River Turnpike Bridge - Answer plug weld, complete fracture in the top
tension chord, unused rivet holes filled with weldment
Hernando de Soto Bridge - Answer T-1 steel was used, similar as Sherman, partial fracture in
tie girder
Fracture Control Plan Factors - Answer Materials, Design and Fabrication
1985 - Answer Elimination of web gaps, designs after this shouldn't involve NSTM members
Why are there more NSTM bridges in north east/ bigger states - Answer Access to resources,
more river crossings
, What is NSTM - Answer primary steel member fully or partially in tension, and without load
path redundancy, system and internal, whose failures may cause a portion of or the entire
bridge to collapse
What is an NSTM inspection - Answer Hands on, touching entire member from front to back
and top to bottom, prior to site visit, must review NSTM procedures and plans and identify
NSTM
NSTM Inspection intervals - Answer Reduced- 12 months
Regular- 24 months
Extended- 48 months
Axial Tension - Answer A force that acts along the longitudinal axis of a member and tends to
pull the member apart
Axial Tension examples - Answer eye bars, cable, wire rope, FB, girders, truss, pin and hanger
Axial Compression - Answer A force that acts along the longitudinal axis of member and
tends to push the member together
Axial Compression Examples - Answer columns, arches, vertical and diagonal trusses
Bending Moment - Answer an external load applied transversely to a bridge member causes
it to bend, produces both compression and tension forces
Bending Moment Examples - Answer beams, rigid frames, FB, pier caps, and cantilevers
Can you see the point of inflection - Answer no, you can guess the area where it could be
Composite action - Answer Deck and superstructure are different materials but act as one
Load Path - Answer deck
superstructure
bearings
substructure
sub surface
Correct Answers.
Silver Bridge 1967 - Answer eye bar chain suspension bridge, unstable internal crack in eye
bar, bridge not maintained well, research began on redundancy, fatigue and failure from this,
NBIS
Mianus River Bridge - Answer pin and hanger was cracked and worsened due to fatigue, pin
separated from hanger, FHWA published " inspection of fracture critical bridge members
Daniel W. Hoan Memorial Bridge - Answer triaxial constraint ending in brittle fracture, two
main girders were completely severed because of a gusset plate and transverse connection
plate
I 35W Bridge - Answer gusset plates were half the thickness they were supposed to be,
bowing was shown
Sherman Minton Bridge - Answer fabrication flaw, cracks in one of the tie girders dating back
to original construction, T-1 steel, which is susceptible to hydrogen induced cracking
I-5 Skagit River Bridge - Answer Semi trailer over loaded directly hit multiple sway struts, not
considered NSTM, but makes inspectors aware of other components that can cause failure,
truck was not in the correct lane
I-276 Delaware River Turnpike Bridge - Answer plug weld, complete fracture in the top
tension chord, unused rivet holes filled with weldment
Hernando de Soto Bridge - Answer T-1 steel was used, similar as Sherman, partial fracture in
tie girder
Fracture Control Plan Factors - Answer Materials, Design and Fabrication
1985 - Answer Elimination of web gaps, designs after this shouldn't involve NSTM members
Why are there more NSTM bridges in north east/ bigger states - Answer Access to resources,
more river crossings
, What is NSTM - Answer primary steel member fully or partially in tension, and without load
path redundancy, system and internal, whose failures may cause a portion of or the entire
bridge to collapse
What is an NSTM inspection - Answer Hands on, touching entire member from front to back
and top to bottom, prior to site visit, must review NSTM procedures and plans and identify
NSTM
NSTM Inspection intervals - Answer Reduced- 12 months
Regular- 24 months
Extended- 48 months
Axial Tension - Answer A force that acts along the longitudinal axis of a member and tends to
pull the member apart
Axial Tension examples - Answer eye bars, cable, wire rope, FB, girders, truss, pin and hanger
Axial Compression - Answer A force that acts along the longitudinal axis of member and
tends to push the member together
Axial Compression Examples - Answer columns, arches, vertical and diagonal trusses
Bending Moment - Answer an external load applied transversely to a bridge member causes
it to bend, produces both compression and tension forces
Bending Moment Examples - Answer beams, rigid frames, FB, pier caps, and cantilevers
Can you see the point of inflection - Answer no, you can guess the area where it could be
Composite action - Answer Deck and superstructure are different materials but act as one
Load Path - Answer deck
superstructure
bearings
substructure
sub surface
