<s>
In	O
numerical	B-General_Concept
analysis	I-General_Concept
,	O
the	O
interval	B-Algorithm
finite	I-Algorithm
element	I-Algorithm
method	I-Algorithm
(	O
interval	B-Algorithm
FEM	I-Algorithm
)	O
is	O
a	O
finite	B-Application
element	I-Application
method	I-Application
that	O
uses	O
interval	O
parameters	O
.	O
</s>
<s>
Interval	B-Algorithm
FEM	I-Algorithm
can	O
be	O
applied	O
in	O
situations	O
where	O
it	O
is	O
not	O
possible	O
to	O
get	O
reliable	O
probabilistic	O
characteristics	O
of	O
the	O
structure	O
.	O
</s>
<s>
The	O
goal	O
of	O
the	O
Interval	B-Algorithm
Finite	I-Algorithm
Element	I-Algorithm
is	O
to	O
find	O
upper	O
and	O
lower	O
bounds	O
of	O
different	O
characteristics	O
of	O
the	O
model	O
(	O
e.g.	O
</s>
<s>
This	O
is	O
so	O
called	O
worst	B-General_Concept
case	I-General_Concept
design	O
,	O
which	O
is	O
closely	O
related	O
to	O
the	O
limit	O
state	O
design	O
.	O
</s>
<s>
Worst	B-General_Concept
case	I-General_Concept
design	O
requires	O
less	O
information	O
than	O
probabilistic	O
design	O
however	O
the	O
results	O
are	O
more	O
conservative	O
[	O
Köylüoglu	O
and	O
Elishakoff	O
1998 ]	O
.	O
</s>
<s>
The	O
Interval	B-Algorithm
Finite	I-Algorithm
Element	I-Algorithm
Method	I-Algorithm
requires	O
the	O
solution	O
of	O
a	O
parameter-dependent	O
system	O
of	O
equations	O
(	O
usually	O
with	O
a	O
symmetric	O
positive	O
definite	O
matrix	O
.	O
)	O
</s>
<s>
where	O
is	O
a	O
stiffness	B-Algorithm
matrix	I-Algorithm
and	O
is	O
a	O
right	O
hand	O
side	O
.	O
</s>
<s>
Because	O
of	O
that	O
the	O
results	O
of	O
the	O
interval	B-Algorithm
finite	I-Algorithm
element	I-Algorithm
(	O
or	O
in	O
general	O
worst-case	B-General_Concept
analysis	O
)	O
may	O
be	O
overestimated	O
in	O
comparison	O
to	O
the	O
stochastic	O
fem	O
analysis	O
(	O
see	O
also	O
propagation	B-General_Concept
of	I-General_Concept
uncertainty	I-General_Concept
)	O
.	O
</s>
<s>
Interval	B-Algorithm
FEM	I-Algorithm
use	O
very	O
similar	O
methodology	O
in	O
multidimensional	O
cases	O
[	O
Pownuk	O
2004 ]	O
.	O
</s>
<s>
In	O
order	O
to	O
assemble	O
the	O
global	O
stiffness	B-Algorithm
matrix	I-Algorithm
it	O
is	O
necessary	O
to	O
consider	O
an	O
equilibrium	O
equations	O
in	O
each	O
node	O
.	O
</s>
<s>
is	O
the	O
global	O
stiffness	B-Algorithm
matrix	I-Algorithm
,	O
</s>
<s>
The	O
interval	B-Algorithm
finite	I-Algorithm
element	I-Algorithm
method	I-Algorithm
can	O
be	O
applied	O
to	O
the	O
solution	O
of	O
problems	O
in	O
which	O
there	O
is	O
not	O
enough	O
information	O
to	O
create	O
reliable	O
probabilistic	O
characteristic	O
of	O
the	O
structures	O
(	O
Elishakoff	O
2000	O
)	O
.	O
</s>
<s>
Interval	B-Algorithm
finite	I-Algorithm
element	I-Algorithm
method	I-Algorithm
can	O
be	O
also	O
applied	O
in	O
the	O
theory	O
of	O
imprecise	O
probability	O
.	O
</s>
<s>
This	O
approach	O
can	O
be	O
also	O
applied	O
in	O
the	O
interval	O
finite	O
difference	O
method	O
and	O
the	O
interval	B-Algorithm
boundary	I-Algorithm
element	I-Algorithm
method	I-Algorithm
.	O
</s>
<s>
This	O
approach	O
can	O
be	O
also	O
applied	O
in	O
the	O
interval	O
finite	O
difference	O
method	O
and	O
the	O
interval	B-Algorithm
boundary	I-Algorithm
element	I-Algorithm
method	I-Algorithm
.	O
</s>
<s>
Muhanna	O
and	O
Mullen	O
applied	O
element	O
by	O
element	O
formulation	O
to	O
the	O
solution	O
of	O
finite	B-Application
element	I-Application
equation	O
with	O
the	O
interval	O
parameters	O
.	O
</s>
<s>
Using	O
that	O
method	O
it	O
is	O
possible	O
to	O
get	O
the	O
solution	O
with	O
guaranteed	O
accuracy	O
in	O
the	O
case	O
of	O
truss	B-Device
and	O
frame	O
structures	O
.	O
</s>
<s>
The	O
solution	O
stiffness	B-Algorithm
matrix	I-Algorithm
and	O
the	O
load	O
vector	O
can	O
be	O
expanded	O
by	O
using	O
perturbation	O
theory	O
.	O
</s>
<s>
Several	O
authors	O
tried	O
to	O
apply	O
pure	O
interval	B-Algorithm
methods	I-Algorithm
to	O
the	O
solution	O
of	O
finite	B-Application
element	I-Application
problems	I-Application
with	O
the	O
interval	O
parameters	O
.	O
</s>
