Group 5.J Anchorage, Part II: Substrates Flashcards
What are the two design considerations when fastening into a metal base material:
Thick base material or
Thin base material.
It should be determined if the base material is thick enough to take advantage of the full _____strength of the fastener or if the thin base material will result in _______ of the fastener before its tensile strength is reached?
tensile
pull-out
When the base appears thick enough so that the
fastener material will fail in tension before it pulls
out, the base material should still be analyzed to
verify that its _______ & ____ ___ capacity are
greater than the tensile strength of the fasteners.
Bearing and pull-out
The internal stresses in the fastener should
be checked according to the relationship of
tension and shear load in the fastener, as well as
design allowable tension and shear ______ the
fastener.
strength of
if the fastener is subjected to combined shear
and tension load, this relationship _____must hold.
The sum of the squared ratios of [Shear load to Allowable shear] and of [tension load and allowable tension], must be less than or equal to 1.0
(St/Sa)^2 + (Tt/Ta)^2 <= 1.0
Second, the bearing capacity of the substrate
material must be greater than the shear load on
the fastener. And, the point at which the fastener
will pull out of the substrate must also be checked
against the tension in the fastener. That is, these
relationships ______ must be satisfied.
The ratio of V shear load to allowable bearing strength of the substrate and the Tension load and allowable pull out strength, must both be less than 1.0
V/A bng <= 1.0 and T/A pull <= 1.0
Unlike steel or concrete substrates, wood
connections generally experience a slower, ductile
failure called _______
Yielding
Pull-out (or withdrawal) capacity of these fastener
types (such as nails, wood screws, lag screws, bolts and spikes) is dependent on the fastener itself, the
____of penetration, ____ type and one or more
end-use adjustment factors as applicable.
depth, wood
End-use adjustment factors that impact pull out capacity of wood fasteners include:
(8 items)
(These pertain to the time and environmental conditions of the loading, the dimensions and geometry of the fastener and other materials involved.)
LWT PTE MD
- Load Duration Factor
- Wet Service Factor
- Temperature Factor
- Penetration Depth Factor
- Toe-Nail Factor
- End Grain Factor
- Metal Side Plate Factor
- Diaphragm Factor
Additional factors for fastening to wood include:
location and clusters
Edge distance:
Group Action Factor.
Edge distance factor pertains to the the distance of the fastener from the ___ or ___ of the material being anchored and of the substrate.
edge or end
Group Action Factor pertains to the _______ and ______of multiple fasteners in relation to one another.
spacing and pattern
Group Action Factor (Cg) pertains to the _______ and ______of multiple fasteners in relation to one another.
spacing and pattern
When figuring the minimum yield capacity of the
connection, the design professional will have to
analyze up to ____ yield limit equations to determine
the controlling value.
six
Concrete and Masonry:
The two modes of failure of wedge type anchors
are assumed to be _____ ____ failure or _____failure.
The calculated anchor capacity would be based on
the ______ (higher / lower) of these two modes of failure.
anchor bolt failure or substrate failure.
lower
All wedge type post-installed concrete anchors
develop a “cone of influence” based on the
______ of the anchor, _____ of anchor
embedment and strength of the substrate.
Diameter, depth
An anchor’s holding capacity is directly related to the
______of concrete that is included in the “cone of
influence,” around the anchor.
volume
The “cone of influence,” around masonry anchors can be depicted as a line starting from the _____of an anchor and radiating upward at a ___ degree angle to the masonry surface,
bottom
45
Anything that reduces the volume of concrete in
the cone of influence reduces the ______ _____ of
that anchor. This occurs when the cones of influence of adjacent masonry anchors overlap.
holding power
A reduction in holding power of masonry anchors can also occur when an anchor’s cone is cut off by being ______________ of the concrete material.
too close to the edge
Analysts should refer to the fastener manufacturer’s technical data for minimum and maximum ______ along with _______ ____ and allowable loads for masonry anchors
spacings, embedment depth
If no technical data is available, a good rule of
thumb to estimate proper spacing of multiple
anchors is that, where no reduction in holding
capacity occurs, spacing should be equal to ____
anchor diameters.
4
10
8
15
10
A separation of five diameters would reduce holding capacity of a given masonry anchor to ___percent. That can also be expressed as a reduction factor of ____
50%
0.5
Holding capacity reduction factors for separation distances between 5 and 10 bolt diameters can be determined by_________.
interpolation.
