Brannigans Building Construction CH.2 Concepts of Construction (pt.2) Flashcards
1
Q
refers to the distribution of loads along a beam
A
beam loading
2
Q
assuming a simple beam can carry 8 units of distributed load, how many units can it carry at the center, cantilevered distributed, and on unsupported cantilever
A
center: 4 units
cantilever distributed: 2 units
unsupported cantilever end: 1 unit
3
Q
the result of force exerted by a beam on a support
A
reaction of beam
4
Q
total reactions of the supports of a beam must equal what?
A
weight of beam and its load
5
Q
the load that will bend of break a beam
A
bending moment
6
Q
heavy loads should be placed directly over or very close to what on a beam?
A
point of support
7
Q
type of beam, framed structure consisting of a triangle or group of triangles arranged in a single plane in such a manner that loads are applied at the points of intersections of the members will cause only direct stresses (tension or compression) in the members
A
truss
8
Q
can support axial loads but are not designed to handle rotational moments
A
trusses
9
Q
top and bottom members of a truss
A
chords
10
Q
compressive connecting members of a truss
A
struts
11
Q
tensile connecting members of a truss
A
ties
12
Q
connection points in a truss
A
panel points
13
Q
in a truss, as a group the struts, ties and panel points are called what?
A
the web
14
Q
type of truss with bottom and top chords parallel
A
parallel chord truss
15
Q
have a very long span and may have a slight upward pitch to center to facilitate water runoff
A
parallel chord roof trusses
16
Q
can be used as roof rafters; provide a peaked rood with usable attic space (dormer windows may be a clue)
A
wooden parallel chord trusses
17
Q
roof truss may be triangular in shape to provide a peaked roof, known as
A
triangular truss
18
Q
can provide huge clear spans yet have a dead weight considerably less than that of a corresponding ordinary beam
A
trusses
19
Q
in a truss what carries compression what carries tension
A
top chord= compression
bottom chord= tension
20
Q
when a truss is cantilevered what carries compression and what carries tension
A
top chord= tension
bottom chord= tension
21
Q
in sketches of trusses how do you determine difference between compression and tension members?
A
compression members= thick lines
tension members= thin lines
22
Q
if a tension member is tied from stub to beam ends at wall what will be formed?
A
triangle (truss)
23
Q
single compression member, compression member extends downward
A
inverted king post truss
24
Q
a truss with 2 compression members
A
queen post truss
25
truss can be designed and constructed as the minimum structure that will carry what?
design load
26
most serious effect of rising roofs is the weakened joints that can results from shrinking wood pulling away from what?
gusset plates
27
made of gusset plates made of small, thin pieces of galvanized sheet steel with teeth punched into one side; teeth are then pressed into 2 pieces of wood to hold them together
lightweight gusset plate trusses
28
a truss is efficient b/c it separates what forces?
compression and tension
29
since top chord on a truss is under compression it responds exactly like what?
a column
30
in a truss, all of the compressive load is carried on the top chord typically by a light member such as what?
2x4 or 2x6
31
except for short trusses, bottom chord (tensile) is made up of 2 or more pieces of wood joined end to end by what?
gusset plates
32
web members of a truss can be connected by what? q
gusset plates or by nailing and gluing
33
structural member that transmits a compressive force along a straight path in the direction of the member
column
34
any structural member that is compressively loaded, despite is attitude, is governed by the laws of (doesn't have to be vertical)
columns
35
nonvertical columns; diagonal columns with brace foundation piling
struts or rakers
36
line of columns in any direction
bent
37
line of columns specially braced to resist wind
wind bent
38
the floor area b/w any 2 bents
bay
39
freestanding masonry load carrying column (in cathedral)
pillar
40
columns lose strength by change in what?
square of the change in length
| i.e. 12 ft column can carry 1/4 load of a 6 ft column
41
most efficient shape for a column is one that distributes the material equally around what?
around the axis as far as possible from the center of the cylinder
42
in cast iron construction in buildings, interior and exterior columns are what shape?
```
interior columns usually circular
wall columns (within exterior walls) are rectangular
```
43
what shape would be the most efficient use of materials under a compressive load in a column b/c it is most nearly circular in cross section
4x4
44
masonry walls under construction are often braced against high winds by what?
scaffold planks usually 2x8 or 2x10
45
simply smoothed off tree trunks
wooden columns
46
beams are shaped like the letter "I" b/c the depth determines what?
strength
47
short, squat columns, fail by crushing
piers
48
fail by buckling, normally assumes "s" shape
long, slender columns
49
can fail by buckling or crushing
intermediate columns
50
very long thin columns are known as what?
Eulers law columns
51
Euler discovered that there is a critical load for a column and that the addtion of even a single atom over the critical load can cause what?
buckling and collape
52
formula for Eulers law
```
P(c) = pie^2 X E(I)/ L^2
p= critical max load
E= modules of elasticity of material in column
I= moment of inertia
L^2= length of column squared
```
53
in Eulers Law formula for column loading, cutting the length of the column in 2 increases the carrying capacity to what?
4 times higher than what it was initially
54
the load carrying capacity of a column can be increased by what?
bracing it
55
resembles a wide slender column; transmits to the ground the compressive forces applied along the top or received at any point on it
wall
56
wind load is an example of what?
flexural force
57
2 main divisions of walls
load bearing wall & non load bearing wall
58
carry a load of some part of the structure in addition to the weight of it itself
load bearing wall
59
support only their own weight (i.e. veneer wall, panel wall aka curtain wall, partition wall)
non-load bearing wall
60
any wall at right angles to any other wall; walls brace one another
cross wall
61
made of single vertical thickness of masonry; designed simply to improve the exterior appearance of the building
veneer wall
62
depends on the underlying wall for stability, should be tied to the wall with metal ties embedded in the mortar
veneer wall
63
composed of 2 or more masonry materials that react together under a load (i.e. brick & concrete block)
composite wall
64
used to contain fire spread; penetration in them that do not meet fire resistance requirements will allow fire to advance through
fire wall
65
difference between panel and curtain walls on framed buildings
panel walls= one story in height
| curtain walls= more than one story
66
load bearing wall common to 2 structures
party wall
67
non load bearing walls that subdivide areas of a floor; may be required to have some fire or smoke resistance and also may be required to extend to underside of floor over or only to ceiling line, leaving void above
partition walls
68
wall typically found in top floor of a wooden frame home in a peaked roof; creates a void space
knee wall
69
wall that bounds a tenant space
demising wall
70
in framed building, designed to help resist force of wind; usually incorporated in required enclosures such as elevator shafts or stair shaft
shear wall
71
wall with outer and inner wythes laid in a courses and finished
rubble masonry wall
72
single vertical thickness of masonry
wythes
73
when a masonry wall is under construction it acts as a what with respect to wind loads received on the face of the wall
cantilever beam
74
when masonry wall has roof placed, the wall with respect to wind loads becomes what?
simple beam supported at both ends
75
acts as a vertical cantilever when being erected and is braced by tormentors or temporary bracing poles
precast concrete tilt slab wall
76
what provides permanent bracing for precast concrete tilt slab walls?
roof
77
masonry structure built on the outside surface of the wall
buttress
78
a masonry column projecting from one or both faces of the wall in which they are located
pilaster
79
made of steel, reinforced concrete, or solid masonry (such as brick or solid block) in a block wall are
wall columns
80
built of 2 wythes separated by a space for rain drainage or insulation (can be built of 2 rows of 4in brick, separated by 4in of space tied together with steel ties)
cavity or hollow wall
81
rain penetrating hollow wall would drain down outer wythe drains to cavity to what?
weep holes at bottom
82
if a wall acts as a unit (i.e. good bond exists between bricks, blocks and mortar)
homogeneous
83
type of roof now more commonly used in large permanent structures
fabric roofs
84
7 different roof types
1. flat roof
2. gable roof
3. mansard roof
4. shed or single pitch roof
5. saltbox roof
6. hip roof
7. gambrel roof
85
tend to push outward at the base, they must be either braced or tied; usually braced by heavy masonry buttresses
arches
86
failing buttressed arches often are tied together with what?
steel rods
87
thrust of a beams vs arch
beam thrust= straight down wall or column
| arch= outward
88
stones that make up an arch
voussoirs
89
an arch is said to spring from where?
point of support
90
portion of circumference of circle
segmental arch
91
point at which arch changes direction
hinges
92
derived from the arch; widely used for industrial and commercial buildings where clear space is required; must be tied together at bottom to resist characteristics outward thrust of the arch by steel reinforcing rods
rigid frame
93
thin plate that is curved and built of concrete; transmits loads along curved surface to supports (can be less than 2 in thick)
shell
94
dome is a what that can be considered a 3d arch
shell
95
formed from large number of triangles of equal size; provide structures with high volume to weight ratios, sheath may be any desired material
geodesic domes
96
manner in which a load is spread from the point of application to the ground
transmission
97
when a load is placed on floorboards they transmit the load to what?
joist on either side of the load point
98
load received by wall is delivered to what?
foundation then ground
99
load delivered to girder is divided among what?
both walls and the column, in proportion to distance
100
nature of the ground and the weight of the structure determine the what?
the foundation
101
almost all foundations today are of
concrete
102
transfer load from one structural element to another
connections
103
a building is said to have what type of connections when the elements are connected by simple connectors such as bolts, rivets, or welded joints; usually not strong enough to reroute forces if members are removed ?
pinned connections
104
in what type of building are connections strong enough to reroute forces if a member is removed
rigid frame building
105
opposing forces within a member pulling the member in opposite directions
shear force
106
tendency of a force to rotate a member
moment
107
a connection that prevents the column and beam sliding past each other
shear connection
108
prevent beam and column from sliding past each other and also prevents rotation of beam around column (bending moment)
moment connection
109
in a steel frame structure a beam that is bolted to a column is what?
shear connection
110
a connection in which beam and column are bolted and welded together (a weld connects b/w beam flanges to the column)
moment connection (considered rigid)
111
structure that includes successive poured castings joined together so that completed building is like on piece of stone; also a rigid frame structure
monolithic concrete structure
112
in a rigid frame structure, if a column is removed it is possible for building to do what with load?
redistribute load to remaining members
113
precast concrete buildings may be pinned or may be made monolithic by use of what, which cast in place concrete unites rods that project from precast sections?
wet joint
114
in an ordinary riveted steel framed building, collapse of a column will cause what?
collapse of all elements supported by that column
115
some steel buildings have connections that redirect overloads to other sections of building known as
plastic design
116
buildings can withstand undesigned loads either what?
vertical or lateral
117
often structural failure is due to what?
failure of connections
118
ways in which connections can fail
1. masonry walls shift out dropping joist
2. beams pull out when heavy loads applied
3. high winds
4. rust on steel connectors
5. concrete disintegrates
119
in many buildings and particularly older buildings, connections may be adequate as long as building is what?
axially loaded
120
used exclusively in masonry work until 1880; water soluble
sand lime mortar
121
since 1940's many building codes have required that a structure be what?
anchored to foundation
122
connections in lightweight wood trusses are held together with steel gusset plates or what (pressed into wood penetrating only 3/8 in)?
gang nail
123
steel heated to 1000*F elongates by how much per 100ft of length ?
9.5 inches per 100 ft
124
if a building is not required to be fire resistive, steel might be what?
unprotected
125
often found in precast reinforced concrete buildings; often used to tie buildings together or to provide some additional resistance to earthquake movement
unprotected steel connections (steel rods and cables)
126
unprotected steel rods and cables can at what temperature?
800*F
127
steel tension rod connections to wooden beam may be hidden where?
cockloft
128
fire where can cause beam connections to fail causing interior collapse?
cockloft fire
129
end of joist cut off at an angle to permit the joist to fall out of the wall (masonry) without damaging the wall;
fire cut
130
heavy timber buildings were often built with these in the 19th and 20th centuries; consists of floor girders set in anchor boxes in walls, which allowed girder to slip out of wall easily
self releasing floors
131
heavy timer buildings would have wood beams connected to columns using what?
post caps
132
if long beams not available, shorter lengths can be what to produce desired length?
spliced together with metal connectors
133
a residential structure will usually be designed for a floor load of about how many psf?
30-40 psf
134
unless the building is what type construction, there is no provision in the design of the structure to prevent failure due to fire
type 1 fire resistive construction cracks
135
you should check for what on exterior walls before entering a structure after defensive or transitional attacks ?
for cracks and signs of pulling away from the roof line
136
water weighs approximately how much per gallon?
8.34 lbs (3.8 kg) per gallon
137
a 1000 gpm master stream will potentially add more than how many lbs to a building in just 1 minute of operation?
more than 8000 lbs or 4 tons of weight
138
if you are breaching a wall and find any evidence that the wall is strengthened at that point, stop and start elsewhere you are likely under what?
concentrated load
139
given the wide spread prevalence of plastics and synthetic fuels as part of fire loads it is important to include what as part of criteria in the development of prefire plans?
HRR estimates
140
the only time supplying a sprinkler system should be stopped is if you are operating on what?
low pressure hydrant grid and sprinkler supply is robbing water pressure needed for attack lines
141
known as firefighter killer, a suspended beams that if fire destroys anchoring connection the beam becomes an undesigned cantilever
theater marquee
142
once what limits are reached in a column, there is little reserve strength left and the column is on verge of total collapse; failure of column is likely to occur much more suddenly than the failure of a beam
compression stress limits
143
proper way to breach masonry wall is to open what?
triangular hole
144
if you are breaching a wall and elements fall apart easily indicating wall is in poor condition you should do what?
cease breaching and find another location to force entry
145
the removal of any part of an arch can cause what?
collapse of entire arch
146
a load of an arch that is what may cause it to collapse?
severely unbalanced load or load outside the center
147
a building with what is designed to collapse inward, without pushing out walls ?
fire cut or self releasing floors
148
represents the ratio of strength of material just before failure to the safe working stress
safety factor
