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Load Tracing 1Lecture 10
Architectural Structures IENDS 231
S2008abn
ARCHITECTURAL STRUCTURES I:STATICS AND STRENGTH OF MATERIALS ENDS 231
DR. ANNE NICHOLS
SPRING 2008
ten
load tracingand types
lecture
Load Tracing 2Lecture 10
Architectural Structures IENDS 231
S2008abn
Structural Loads• gravity acts on mass (F=m*g)• force of mass
– acts at a point• ie. joist on beam
– acts along a “line”• ie. floor on a beam
– acts over an area• ie. people, books,
snow on roof or floor
Load Tracing 3Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Tracing• how loads are
transferred– usually starts at top– distributed by
supports as actions– distributed by
tributary areas
Load Tracing 4Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Tracing
tributary area
Load Tracing 5Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Tracing• tributary load
– think of water flow– “concentrates” load of
area into center
( )widthtributaryarealoadw ×⎟
⎠⎞
⎜⎝⎛=
width
Load Tracing 6Lecture 10
Architectural Structures IENDS 231
S2008abn
Load TracingPatcenterRogers 1986
Load Tracing 7Lecture 10
Architectural Structures IENDS 231
S2008abn
Load TracingAlamillo BridgeCalatrava 1992
Load Tracing 8Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Paths
Load Tracing 9Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Paths• wall systems
Load Tracing 10Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Paths• openings & pilasters
Load Tracing 11Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Paths• foundations
Load Tracing 12Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Paths• deep foundations
Load Tracing 13Lecture 10
Architectural Structures IENDS 231
S2008abn
Concentrated Loads
Load Tracing 14Lecture 10
Architectural Structures IENDS 231
S2008abn
Distributed Loads
Load Tracing 15Lecture 10
Architectural Structures IENDS 231
S2008abn
Distributed Loads• statically determinate beam supports
– simple
– overhang
– cantilever
L
L
L
Load Tracing 16Lecture 10
Architectural Structures IENDS 231
S2008abn
Distributed Loads• continuous beams
– statically indeterminate– floors
L L
Load Tracing 17Lecture 10
Architectural Structures IENDS 231
S2008abn
Equivalent Force Systems• replace forces by resultant• place resultant where M = 0• using calculus and area centroids
dx
w(x)
x
L
loadingloading
L
0AdAwdxW === ∫∫
dx
y
x
elx
Load Tracing 18Lecture 10
Architectural Structures IENDS 231
S2008abn
Area Centroids• Table 7.1 – pg. 242
b
h3b
right triangle only
Load Tracing 19Lecture 10
Architectural Structures IENDS 231
S2008abn
Load Areas• area is width x “height” of load• w is load per unit length• W is total load
x
x/2
W
x/2
x
2x/3
W/2
x/3
x
x/2
W
x/6 x/3
W/2
0
Wxw =⋅ w w 22Wxw
=⋅
w 2w
