Transcript thin-walled structures research group

thin-walled structures research group
Fall 2002
Ben Schafer
Testing of cold-formed steel beams
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Jack Spangler
Jim Kelly
Cheng Yu
…most of the CE Grads
Sam Phillips
Liakos Ariston
Tim Ruth
Andrew Myers
…other CE undergrads
Michael Manness, Jr.
Cold-formed steel beams
cheng yu
• Testing
– first tests with definitive
separation of modes
– upper and lower bound
flexural capacities
– experimental evidence for
new design methods
Distortional
• FE Modeling
– parametric studies
– moment gradient effect
– influence of restraint
• Significant design impact
Local
EA/GA and member optimization
sam phillips
Special: 2 hour “Short Course”
Thursday September 26, 2002
1:00pm to 3:00pm
Shaffer Hall Room 101
Evolutionary Computation and Civil/Structural Engineering:
A Look Back and a Look Forward
Assoc. Prof. Chris Foley Marquette University
collapse of thin-walled members
badri hiriyur
P
P
P
kx

x
PP
P PP
PP
Pcrx P
P crx
P
crx
Pˆ x ˆPˆ
x
PPxPx
Px
F
oo
P
PPcrxcrxcrx
Pxm
PPxm
xm
kx
x
) unstable sway mode
P
M

ˆ
PˆP
Pˆ
k
y
Pxm
PPxm
xm
k

PP 
P
cocoup 
c
up led 
led * oup
le
*
cr
(b) unstable sway mode
P
L/2

oo

PPcrcr
P o
PP
cr
PPcr
Pcr
ˆ
PˆP
Pˆ
d*
Pxm
Pxm
Pm
P
Pm
Pm
PPmm


oo
P
PxmPcrcr
Pcr
PP 
P
PPmm
oo
x



P
PPcrxcrxcrx
PPxPx
Px
L/2
x
Fy
Pˆ x ˆPˆ
x
Pm
m



collapse of corrugated plastic pipe
V1
L21
C10
symmetry enforced
at crown
symmetry along
edges enforced
web/s
idewa
ll
crest
liner
valley
cross-section
symmetry enforced
at springline
Y
X
Z
generalized beam theory
puneet bajpai
Unifies the conventional theories
Better understanding of structural principles
Economical method of analysis
Capability to consider individual buckling modes
and select combinations of them
Applicable to linear analysis (First-order GBT),
linear stability analysis (General second-order
GBT), or bifurcation problems
Basic equation of second-order theory :
E kC kV ''''  G k D k V ''  k B k V  
i
where, E = Young’s modulus, G = shear modulus,
k
C, k D, k B
ijk

k

 ( i W jV ' ) '  k q
ijk
j
V = generalized deformation in mode k
k
= section properties applicable to mode k, q = distributed load applicable to mode k,
= three dimensional array of second-order terms, which includes coupling terms
Stochastic post-buckling
jie li, prof. lori graham
l/lc = 1 + ax + bx2 + …,
V = lcV0 + (alcV0 + V1)x + (blcV0 + V2)x2 + …
covered wooden bridges
dylan lamar (u of ark), erika stoddard, steve buonopane
Pine Grove Bridge - Lancaster Co., PA
Brown Bridge - Rutland Co., VT
Reliability and advanced analysis
steve buonopane, prof. tak igusa
Ziemian frame testbed problem
Strength at first plastic hinge
no correlation
to ult. strength
Ultimate Strength (via Adv. Anal.)
Failure probability estimation
Solver efficiency for reliability and optimization
zailong wan, prof. dan naiman, prof. tak igusa
input
building realization(s) 
building
basic geom.
basic loads
perf. criteria
deterministic response study
seek efficiency through
{F}=[Kt]{d}
topology
[Kt]=
MASTAN
interface
•symm.
•pos-def.
•sparse
•topology
unchanging
wind on low-rise buildings
prof. nick jones
Hurricane Loss Reduction
Wind and Structural Engineering Initiative
through
National Institute of Standards and Technology
Building and Fire Research Laboratory
Gaithersburg, Maryland