Concrete Beam Economics Bob Lawrence Alan Schuetz James Giancaspro Mark McDonnell

Agenda n Problem Statement n Concrete Assumptions n Example of Spreadsheet Program n Economics of a Concrete Beam n Alternative Solutions n Concrete n Steel n Economic Assumptions for Concrete and Steel n Costs for Concrete and Steel Beams n Conclusion

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

Economic Assumptions Concrete n Concrete Beam length shall be from 0 to 50 n Water, Sand, Aggregate and Steel will have constant unit prices. n The price of water came from the Seattle Public Works. n The prices for Sand, Steel and Aggregate were taken from Engineering News Report. n The unit prices for Sand, Aggregate and Steel are calculated through a 20 city average.

Concrete Economic Assumptions Cont. n Only three types of concrete beams will be studied: Box, T, and L n Concrete Beams have a life span of 50 years n Labor cost will be the same for all 3 types n Concrete beams require negligible maintenance n At the end of 50 years the beam has no salvage value and is recycled

Spreadsheet Presentation

Spreadsheet Economics n 10 Beam n n Total Material Cost For A Box Beam$ n n Total Material Cost For A T-Beam$54.07 n n Total Material Cost For A L-Beam$59.55 n n 20 Beam n n Total Material Cost For A Box Beam $ n n Total Material Cost For A T-Beam $ n n Total Material Cost For A L-Beam$271.65

Spreadsheet Econ. Cont. n 40 Beam n n Total Material Cost For A Box Beam$2, n n Total Material Cost For A T-Beam$1, n n Total Material Cost For A L-Beam$1, n 50 Beam n n Total Material Cost For A Box Beam$4, n n Total Material Cost For A T-Beam$2, n n Total Material Cost For A L-Beam$2,325.37

Alternatives n Steel Beams n Wood n Plastic Lumber

Alternative Cont. n 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 n Benefits –Cheap Materials –Can hold same load as Steel –Durable –Low Maintenance –No Finishing Required n Negatives –Shorter life span –Doesnt allow for taller structures –Concrete cannot take tensile force

Steel n Benefits –Long Life span –Has Salvage value –Allows for taller structures –Works equally as well in tension and compression n Negatives –High Maintenance –More expensive than concrete

Assumptions for Concrete/Steel Comparison n Safety and Strength for steel and concrete beams will be set equal so there will be an even comparison n Installation cost for steel and concrete beams are the same n When disassembled neither will have an effect on the environment so that will not be considered. n Assume 3 Masons can construct a concrete beam in 1 hour (pre-molded)

Assumptions Cont. n Steel beam must be painted every 7 years or they will rust n We will terminate our economic comparison at 49 years so the study times will be equal n MARR 10% n The spreadsheet program assumes all steel is 60 ksi. n The price of steel is a national average. n The current recycling value of steel is $90.00/ton

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

Materials Cost Comparison n Concrete Beam n 50 in length Total Material Cost For a Box Beam$4, Total Material Cost For a T-Beam$2, Total Material Cost For a L-Beam$2, n Steel Beam n 50 in length n W $25,935 n W $27,560

Maintenance Concrete n Concrete Beam n Maintenance cost is very near zero

Maintenance Steel n Steel must be painted every 7 years n Assume 2 painters can cover 3,600 sq. ft per day n They are paid $.11 per sq. ft. n Paint cost $.05 per sq. ft. n One beams cost are: Labor:$396 Paint:$90

Labor Cost Concrete n Labor Cost for Concrete and Steel are the same except for the beam must be formed out. n Assume 3 masons per beam n Assume Mason Labor Rate: $27.52/hour n Cost per beam: $82.56

Salvage Value n Concrete n Concrete has salvage value of approximately zero n Steel n 50 Length n W Salvage Value: $1908 n W Salvage Value: $1795.5

Cost Comparison Per 50 Beam Cost Comparison Per 50 Beam n Concrete Annual Worth n Labor $8.33 n Materials –Box$ –T$ –L$ n Salvage $0 n Maintenance $0 n Steel Annual Worth n Materials –W $ –W $ n Maintenance – Both beams $ n Salvage –W $1.72 –W $1.62

Total Costs n Total Costs n Concrete –Box-$437 –T-$ –L-$243 n Steel –W $ –W $

Conclusion n The main purpose of our project was to set up a Spreadsheet that calculates material prices for concrete beams n Although through comparison our recommendation would be for Concrete Beams