Concrete Beam Economics

plantcitybusinessUrban and Civil

Nov 26, 2013 (3 years and 7 months ago)

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Concrete Beam Economics

Bob Lawrence

Alan Schuetz

James Giancaspro

Mark McDonnell

Agenda


Problem Statement


Concrete Assumptions


Example of Spreadsheet Program


Economics of a Concrete Beam


Alternative Solutions


Concrete


Steel


Economic Assumptions for Concrete and Steel


Costs for Concrete and Steel Beams


Conclusion

Problem Statement


To develop a cost analysis of a concrete
beam using multiple parameters and
compare the final cost with alternative
methods

Economic Assumptions
Concrete


Concrete Beam
length shall be from
0’ to 50’


Water, Sand,
Aggregate and Steel
will have constant
unit prices.


The price of water
came from the
Seattle Public Works.


The prices for Sand,
Steel and Aggregate
were taken from
Engineering News
Report.


The unit prices for
Sand, Aggregate
and Steel are
calculated through a
20 city average.


Concrete Economic
Assumptions Cont.


Only three types of
concrete beams will
be studied: Box, T,
and L


Concrete Beams
have a life span of
50 years


Labor cost will be
the same for all 3
types


Concrete beams
require negligible
maintenance


At the end of 50
years the beam has
no salvage value
and is recycled

Spreadsheet Presentation

Spreadsheet Economics


10’ Beam


Total Material Cost For A Box Beam

$108.46





Total Material Cost For A T
-
Beam

$54.07




Total Material Cost For A L
-
Beam

$59.55




20’ Beam


Total Material Cost For A Box Beam $496.02



Total Material Cost For A T
-
Beam


$243.12


Total Material Cost For A L
-
Beam

$271.65




Spreadsheet Econ. Cont.


40’ Beam


Total Material Cost For A Box Beam

$2,515.91




Total Material Cost For A T
-
Beam

$1,194.46



Total Material Cost For A L
-
Beam

$1,388.35




50’ Beam


Total Material Cost For A Box Beam

$4,248.96




Total Material Cost For A T
-
Beam

$2,049.36




Total Material Cost For A L
-
Beam

$2,325.37



Alternatives


Steel Beams


Wood


Plastic Lumber

Alternative Cont.


We only considered Steel because
Plastic Lumber is still in the
developmental stage and the amount of
Wood needed to hold an equal load is
impractical

Concrete


Benefits


Cheap Materials


Can hold same load
as Steel


Durable


Low Maintenance


No Finishing
Required


Negatives


Shorter life span


Doesn’t allow for
taller structures


Concrete cannot take
tensile force

Steel


Benefits


Long Life span


Has Salvage value


Allows for taller
structures


Works equally as
well in tension and
compression


Negatives


High Maintenance


More expensive than
concrete


Assumptions for
Concrete/Steel Comparison


Safety and Strength
for steel and
concrete beams will
be set equal so
there will be an
even comparison


Installation cost for
steel and concrete
beams are the same


When disassembled
neither will have an
effect on the
environment so that
will not be
considered.



Assume 3 Masons
can construct a
concrete beam in 1
hour (pre
-
molded)

Assumptions Cont.


Steel beam must be
painted every 7
years or they will
rust


We will terminate
our economic
comparison at 49
years so the study
times will be equal


MARR 10%


The spreadsheet
program assumes
all steel is 60 ksi.


The price of steel is
a national average.


The current
recycling value of
steel is $90.00/ton

Steel Beams


There are only two steel beam that can
hold the 10,000 lb. live and dead load
we have specified for the concrete
beams


They are the:




W36
-

848




W36
-

798

Materials Cost Comparison


Concrete Beam


50’ in length


Total Material Cost For a
Box Beam

$4,248.96



Total Material Cost For a
T
-
Beam

$2,049.36



Total Material Cost For a
L
-
Beam

$2,325.37






Steel Beam


50’ in length


W36
-

798



$25,935


W36
-

848



$27,560




Maintenance Concrete


Concrete Beam


Maintenance cost is very near zero

Maintenance Steel


Steel must be painted every 7 years


Assume 2 painters can cover 3,600 sq.
ft per day


They are paid $.11 per sq. ft.


Paint cost $.05 per sq. ft.


One beam’s cost are:



Labor:

$396



Paint:

$90

Labor Cost Concrete


Labor Cost for Concrete and Steel are
the same except for the beam must be
formed out.


Assume 3 masons per beam


Assume Mason Labor Rate: $27.52/hour


Cost per beam:





$82.56

Salvage Value


Concrete


Concrete has
salvage value of
approximately zero


Steel


50’ Length


W36
-

848


Salvage Value: $1908


W36
-

798


Salvage Value: $1795.5



Cost Comparison

Per 50’ Beam


Concrete Annual Worth


Labor $8.33


Materials


Box

$428.72


T

$206.78


L


$234.63


Salvage $0


Maintenance $0


Steel Annual Worth


Materials


W36
-

848 $2616.84


W36
-

798 $2780.80


Maintenance



Both beams $238.73


Salvage


W36
-

848 $1.72


W36
-
798 $1.62



Total Costs


Total Costs


Concrete


Box

-
$437


T

-
$215.16


L


-
$243


Steel


W36
-

848
-
$3017.81


W36
-

798

-
$2853.95


$0.00
$500.00
$1,000.00
$1,500.00
$2,000.00
$2,500.00
$3,000.00
$3,500.00
Total Cost
BOX
T
L
848
798
Conclusion


The main purpose of our project was to
set up a Spreadsheet that calculates
material prices for concrete beams


Although through comparison our
recommendation would be for Concrete
Beams