Chapter 11 Lightweight Word Truss Collapse Flashcards

1
Q

What are the two types of wood truss systems

A

heavy timber truss

lightweight wood truss

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2
Q

building code defines heavy timber roof construction as wood dimensions at least

A

4 inches wide

6 inches deep

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3
Q

lightweight wood truss incorporates wood members which can be as small as

A

2 inches wide

4 inches deep

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4
Q

sheet metal fasteners only penetrate the wood….

A

1/4” - 1/2”

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5
Q

By engineering calculations and practical firefighting experience lightweight trussed rafters may be expected to collapse after

A

10 minutes in a fully developed fire

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6
Q

In any structural elements, the critical area subject to failure during fire is

A

the point of contact

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7
Q

the most serious deficit in the surface fastener connecting lightweight wood truss is ___

A

the insufficient depth of penetration, half-inch

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8
Q

even if the fire is not of sufficient intensity to try the word heat from the flames can warp the thin sheet metal causing

A

to curl up and pull away from the truss

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9
Q

Aside from insufficient depth of penetration and warping due to heat from flames, what other deficits do surface fasteners have

A
  1. lightweight wood trusses are prefabricated rough handling can loosen minimal surface fasteners before installation
  2. moisture and chemicals to treat wood can cause corrosion on fasteners
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10
Q

how does lightweight wood truss allow fire to spread easily

A

it allows lateral movement of the fire in comparison to solid wood beams which would passively hold fire better in concealed spaces… truss have open design

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11
Q

what is the recommended strategy for fighting fire in buildings with lightweight wood truss floors or roof

A

1.

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12
Q

what is the recommended strategy for fighting fire in buildings with lightweight wood truss floors or roof

A
  1. contents fire- extend line and extinguish content (sofa)
  2. structure fire- in the fire involves a structuring is burning through the concealed roof or floor spaces, defensive strategy
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