Rigid Frames 1
Lecture 12
Foundations Structures
ARCH 331
S2009abn
FOUNDATIONS STRUCTURES:
FORM, BEHAVIOR, AND DESIGN
ARCH 331
DR. ANNE NICHOLS
SPRING 2009
lecture
twelve
rigid frames:
compression & buckling
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Rigid Frames Lecture 12: Foundations - Moment Redistribution, Behavior, and Design - Prof., Study notes of Architecture
A set of lecture notes from a university course on foundations structures, specifically focusing on rigid frames. The notes cover topics such as compression and buckling, moment redistribution, lateral load resistance, and bracing. The notes also discuss the behavior of rigid frames, including how moments get redistributed and how deflections are smaller in rigid frames compared to other types of structures.
Typology: Study notes
Pre 2010
1 / 35
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Rigid Frames Lecture 12: Foundations - Moment Redistribution, Behavior, and Design - Prof. and more Study notes Architecture in PDF only on Docsity!
Rigid Frames 1Lecture 12
Foundations Structures
ARCH 331
F
OUNDATIONS
S
TRUCTURES
:
F
ORM,
B
EHAVIOR, AND
D
ESIGN
ARCH 331D
R.
A
NNE
N
ICHOLS
S
PRING 2009
lecture
twelve rigid frames:compression & buckling
Rigid Frames 2Lecture 12
Foundations Structures
ARCH 331
Rigid Frames •^
rigid frames have nopins
-^
frame is all one body
-^
joints transfermoments and shear
-^
typically staticallyindeterminate
-^
types^ –
portal
gable
Rigid Frames 4Lecture 12
Foundations Structures
ARCH 331
Rigid Frames
moments get redistributed
deflections are smaller
effective column lengths are shorter
very sensitive to settling
Rigid Frames 5Lecture 12
Foundations Structures
ARCH 331
Moment Redistribution •^
continuous slabs & beams with uniformloading^ –
joints similar to fixed ends, but can rotate
-^
change in moment to center =^ –
M
max
for simply supported beam
2
wL
Rigid Frames 7Lecture 12
Foundations Structures
ARCH 331
Rigid Frames •^
staggered truss^ –
rigidity
clear stories
Rigid Frames 8Lecture 12
Foundations Structures
ARCH 331
Rigid Frames •^
connections^ –
steel
concrete
Rigid Frames 10Lecture 12
Foundations Structures
ARCH 331
S2009abn
Braced Frames •^
types of bracing^ –
knee-bracing
diagonal
X
K or chevron
shear walls
diagonal
X
K (chevron)
shear walls
Rigid Frames 11Lecture 12
Foundations Structures
ARCH 331
Shear Walls •^
resist lateral load in plane with wall
Rigid Frames 13Lecture 12
Foundations Structures
ARCH 331
Column Buckling •^
axially loaded columns
-^
long & slender^ –
unstable equilibrium =
buckling
sudden and not good
Rigid Frames 14Lecture 12
Foundations Structures
ARCH 331
Modeling •^
can be modeled with a spring at mid-height
- •^
when momentfrom deflectionexceeds thespring capacity... “boing”
-^
critical load P
Rigid Frames 16Lecture 12
Foundations Structures
ARCH 331
Buckling Load •^
related to deflected shape (P
•^
shape of sine wave
-^
Euler’s Formula
-^
smallest
I
governs
(^
(^2) )
2 L
EI
P
critical
π
Rigid Frames 17Lecture 12
Foundations Structures
ARCH 331
S2009abn
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
2
(^2) e
critical
r
L
EA
P
Rigid Frames 19Lecture 12
Foundations Structures
ARCH 331
Effective Length •^
end conditions affect shape
-^
effective length factor, K
L
K
L
e^
Rigid Frames 20Lecture 12
Foundations Structures
ARCH 331
Bracing •^
bracing affects shape of bucklein one direction
-^