Joining Steel Members Flashcards
What are the three primary methods of joining steel members?
- rivets
- bolts
- welds
What is the first step of riveting?
while-hot fastener is inserted through holes in members to be fastened
What is the second step of riveting?
fastener is hammered to produce a head on the plain end
What is the final step of riveting?
as the metal cools, it contracts, and tightly clamps the steel members
Where is riveting typically found?
mostly found in historic structures
Is riveting used in modern construction?
rarely
What are the characteristics of carbon steel bolts? (3)
- relatively low strength
- limited uses, such as fastening light framing elements or holding temporary connections
- also called common, or unfinished bolts
What are the characteristics of high-strength bolts? (2)
- stronger than common bolts
- used for fastening primary structural members
What is a bearing-type connection?
bolts need only be installed to ‘snug tight’ condition
What is a slip-critical type connection?
bolts are tightened to such an extent that the friction between steel members resists movement
How do bearing-type connections resist movement?
body of bolt resists movement between connected members by bearing directly against sides of bolt holes
How are bearing-type connections stressed?
bolt is stressed in shear
How do bearing-type connections reach full strength?
connection will slip before it reaches full strength
How do slip-critical connections resist movement?
bolt is tensioned to such an extent that movement in the joint is resisted by friction between the adjoining surfaces of the steel members
How are slip-critical connections stressed?
bolt is very highly stressed, but not in tension
Do slip-critical connections experience slippage?
no
When are slip-critical connections required?
required where joints experience load reversals, in highly-stressed joints, or where slippage would be detrimental
What must be assured in slip-critical connections?
proper bolt tension
How tight must bolts be in slip-critical connections?
bolts must be tightened to at least 70% of their ultimate tensile strength
How is the proper bolt tension verified for slip-critical connections? (4)
- turn-of-nut method
- load indicator washers
- calibrated wrench method
- tension control bolts
What is the turn-of-nut method?
nut is tightened some additional fraction of a turn after achieving snug condition
What are load indicator washers? (3)
- when bolt is adequately tensioned, protrusions on the washer are flattened
- bolt tension is verified by inserting a gauge between bolt head and washer
- some load indicator washers squirt dye when adequate tension is achieved, making inspection easier
What is the calibrated wrench method? (2)
- torque wrench used to tighten bolts
- less frequently used
What are tension control bolts? (4)
- requires the use of specialized tool
- when bolt is adequately tightened, the splined end snaps off
- proper bolt tension is verified by absence of spline
- this method allows tightening with access to only one side of the bolt
