Download Rigid Frames - Compression and Behavior - Lecture Slides | ARCH 614 and more Study notes Architecture in PDF only on Docsity!
Rigid Frames 1Lecture 11
Elements of Architectural Structures
ARCH 614
S2009abn
E
LEMENTS OF
A
RCHITECTURAL
S
TRUCTURES
:
F
ORM,
B
EHAVIOR, AND
D
ESIGN
ARCH 614D
R.
A
NNE
N
ICHOLS
S
PRING 2009
lecture
eleven rigid frames:compression & buckling
Rigid Frames 8Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames •^
rigid frames have nopins
-^
frame is all one body
-^
joints transfermoments and shear
-^
typically staticallyindeterminate
-^
types^ –
portal – gable
Rigid Frames 9Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames •^
behavior
Rigid Frames 10Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames
moments get redistributed
deflections are smaller
effective column lengths are shorter
very sensitive to settling
Rigid Frames 11Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames •^
resists lateralloadings
-^
shape depends onstiffness of beamsand columns
-^
90° maintained
Rigid Frames 12Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames •^
staggered truss^ –
rigidity
clear stories
Rigid Frames 13Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frames •^
connections^ –
steel
concrete
Rigid Frames 14Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Braced Frames •^
pin connections
-^
bracing to prevent lateral movements
Stability and Columns 15Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Modeling •^
can be modeled with a spring at mid-height
when momentfrom deflectionexceeds thespring capacity... “boing”
-^
critical load P
Stability and Columns 16Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Effect of Length •^
long & slender
•^
short & stubby
Stability and Columns 17Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Buckling Load •^
related to deflected shape (P
Δ
•^
shape of sine wave
-^
Euler’s Formula
-^
smallest
I
governs
(^
(^2) )
2 L
EI
P
critical
π
Stability and Columns 18Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Critical Stress •^
short columns
-^
slenderness ratio = L
/r (L/d)e
•^
radius of gyration =
I A
r^
a
actual
critical
F
A
P
f^
weak axis
(^
)^
2
2
(^22)
2
r
L
E
L
A
EAr
A
P
f
e
e
critical
critical
π
π
2
(^2) e
critical
r
L
EA
P
π
Stability and Columns 19Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Critical Stresses •^
when a column gets stubby, F
y^
will limit the
load for steel
-^
real world has loads with eccentricity
Stability and Columns 20Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Effective Length •^
end conditions affect shape
-^
effective length factor, K
L
K
L
e^
Stability and Columns 21Lecture 22
Elements of Architectural Structures
ARCH 614
S2004abn
Bracing •^
bracing affects shape of bucklein one direction
-^
both should be checked!
Column Eccentricity 18Lecture 23
Elements of Architectural Structures
ARCH 614
S2004abn
Centric & Eccentric Loading •^
centric^ –
allowable stress from strength or buckling
-^
eccentric^ –
combined stresses
Rigid Frames 18Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frame Analysis
need support reactions
free body diagram each member
end reactions are equal and opposite onnext member
“turn” memberlike beam
draw V & M
Rigid Frames 19Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frame Analysis
FBD & M
-^
opposite endreactions at joints
M+
P
Rigid Frames 24Lecture 25
Elements of Architectural Structures
ARCH 614
S2004abn
Rigid Frame Design •^
columns in frames^ –
ends can be “flexible”
stiffness affected by beamsand column = EI/L
for the joint
-^
lc^
is the column length of each column
-^
lb
is the beam length of each beam
-^
measured center to center
c l b
EI
l
EI
G
Σ Σ
Ψ =
Rigid Frames 19Lecture 26
Elements of Architectural Structures
ARCH 614
S2006abn
Rigid Frame Design •^
column effective length, k
A B
Rigid Frames 29Lecture 11
Elements of Architectural Structures
ARCH 614
S2008abn
Tools – Multiframe4D •^
in computer lab
Rigid Frames 30Lecture 11
Elements of Architectural Structures
ARCH 614
S2008abn
Tools – Multiframe4D •^
frame window^ –
define frame members
-^
or pre-defined frame
select points, assign supports
select members,assign section
load window
select point or member,add point or distributed
loads
Rigid Frames 31Lecture 11
Elements of Architectural Structures
ARCH 614
S2008abn
Tools – Multiframe4D •^
to run analysis choose^ –
case menu
-^
Analyse...
-^
Linear (
st^
order elastic)
-^
plot^ –
choose options
-^
results^ –
chooseoptions
