Standard Code for Fire Egress

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26 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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Keith Evan Green, RA, PhD


Standard Code for Fire Egress

Required exits shall provide continuous and uninterrupted means of egress form one story to
another and to an outside exit. The distance from a point in a floor to a vertical exit, a
horizontal exit
or an outside exit measured along the line of travel
will not exceed 150 feet
.

The maximum travel distance to an exit from the end of a corridor shall
not be more than 20

feet
. All stairs and corridors required as exits shall be not less than
forty
-
four i
nches in width
.


Common building bay sizes

20’x20’, 20’x40’, 30’x30’
(or close to these, such as 18’ x 36’
, 24’ square, …
)

For example, a 30’x30’ bay is comprised of columns which are 20” square in plan with
a concrete slab, 13” thick. The slab can be as
little as 8” thick if it is post
-
tensioned in
two directions (“2
-
way post
-
tensioned”). The slab thickness as well as the dimensions
of the cross
-
section (plan) of the column can also be reduced with the addition of a
“drop panel” (square portion of concret
e at interface of slab and column, as shown
here), but it is more difficult to get the mechanical equipment to fit.


Recognize that, with a free plan and with curtain wall technologies, your walls do not
need to fall on column lines but can "dance" between
them. As well, if you calculate
that you do
not
need a full bay along the face of your building (or
,
you will otherwise
waste space), then you can have a smaller bay size in one dimension for that bay.
For example, at the Sunoco
Institute across from Lee
Hall
, the bay along the front
face is not as deep as the bay behind it
--

it
just do
esn’t
need all that space. In this
case, the building might be over
-
engineered
for the smaller bay
or the
steel
beams on
the less
-
deep bay might
be of smaller
dimension
s
.












Rules
-
of
-
thumb for structural members in concrete construction

1. Beams:

a. Overall depth of beams = span /5

b. With of beams = depth/2

2. Columns:

a. Minimum dimension is 8” on a side

b. Cross sectional area in square inches = load (in psi)/
1000

3a. Floor structures
/
Slabs without joist ribs
(i.e. flat slabs; common in multi
-
family housing):

a.
Slabs spanning up to 12’ in the direction
of the deflection.

b. Thickness of the slab = span/20

-
OR
-

a.
Slabs spanning up to 24’x 24’
(i.e. 576 s
q. ft.)

b. Thickness of the slab = span/30

3b. Floor structures
/
Slabs with one
-
way joist ribs
:

a.
slabs spanning from 12’ to 30’ in the direction
of the deflection.

b. good for oblong bays

c. overall depth of slab plus joist ribs = span/20 + 2 ½”

d.
common spacing of 20” and 30” between ribs

e. joists commonly have a width of 5” to 9”

3c. Floor structures
/
Two
-
way spans
:

a. Waffle slabs are used for
24’ to 50’ in the large dimension
(maximum of 2500 sq. ft.)

b. Overall thickness of slab and joist
rib = span/30 + 2 ½”

c. Rectangular modules have common linear dimensions of 2’,3’, 4’, & 5’


> helpful
website: www.concreteonline.com


Rules of Thumb for Steel Construction


Depth
(in inches)
of Roof Beams
and
Joists =
0.5 x
Length


Depth
(in inches)

of Floor Beams
and
Floor Joists

= 0.6
x
Length


Hinge or splice location for cantilever

or continuous roof systems

is 15% to 25% of
span length


Rules of Thumb for Joists


Floor
joist thickness vs. span info from joist manufacturers
:

http://www.trulinetruss.com/html/floor_span_tables_
-
_ijoist.htm

http://www.trimjoist.com/spans.html

http://www.ufpi.com/PRODUCT/oj/prod/faq.htm



Rules of Thumb for Block Wall










A non
-
shared block wall is
3 5/8” brick

+ 1” air

+ 1”
-
2” rigid insulation

+ 7 5/8” CMU
block

+ 1 ½” airspace and drywall channel

+ ½” drywall

=

15 ¼”

16
¼” total wall
thickness from outside to inside
.


More i
nfo on block wall construction:

http://www.maconline.org/tech/design/thinksystems/thinksystems.html

http://faculty.delhi.edu/hultendc/A220
-
Week2
-
Lecture
-
Web.html

http://faculty.delhi.edu/hultendc/ARCH220
-
Main.htm