Taking into account construction, transportation, direct, and indirect costs over the life of a parking garage leads to what is perhaps the most impacting structural cost analysis - life-cycle cost.
From day one of the project, simple, easy to assemble HDG steel frame designs will cost less to build and save time (and therefore, money) in the construction phase. Because fewer beams and pieces are required to do the same amount of work, transportation fees are also reduced. A design material like concrete, conversely, will require heavy, cumbersome pieces to be transported at great expense, fitted together using costly special efforts and machinery, and will likely require continuous maintenance and upkeep until eventual failure due to spalling or deterioration.
Costs During Use
During the use phase of the project, the galvanized frame structure will remain maintenance free for decades; saving money on labor and materials, while ensuring indirect costs such as loss of business due to maintenance closures will be eliminated. Using a paint coating for corrosion protection, on the other hand, requires maintenance multiple times throughout the life of the structure, increasing lifetime expenses with each touch-up. Hot-dip galvanized steel not only saves you money initially, it also ensures your initial cost is likely the only expense you will have over the life of the parking garage.
All these combined equal huge savings over the life of the project. Structural engineers and others who have studied life-cycle costs conclude steel framed structures are usually less expensive over the life of the project.4 Parking industry experts have indicated over a 50-year life, the cost to maintain a precast concrete deck and frame system is between 5 and 8 cents per square foot, while the cost to maintain a post-tensioned deck on a steel frame is between 3 and 5 cents per square foot — a savings of 40 percent. 1
Calculating life-cycle cost can be a very cumbersome task, but the potential headache of running the analysis is much less painful than the reality of unexpected maintenance costs in the future. To ease part of the burden, the American Galvanizers Association (AGA) has developed an automated calculator based on survey data collected by the AGA from galvanizers and by KTA Tator5 from paint contractors that will compare the initial and life-cycle costs ofHDG to 30+ other steel corrosion protection systems.
The Life-Cycle Calculator (LCC) is an unbiased tool that allows the user to input project-specific variables - such as environment, coating system type, shop or field application, size of project, and estimated interest and inflation rates - to compare the initial and life-cycle costs of HDG to 30+ other steel corrosion protection systems. Using calculations based on standard financial equations of net future value (NFV) and net present value (NPV), the LCCC delivers a detailed comparison of initial and total project costs and the average equivalent annual cost (AEAC), in a one-page printout.
Life-Cycle Cost Case Study
Below is the summarization of a life-cycle cost comparison of hot-dip galvanizing versus a 3-coat paint system for the Cincinnati Children's Hospital Garage, developed by inputting the project specifications below into the the online Life-Cycle Calculator prompts.
For the Cincinnati Garage, utilizing galvanized steel generates a cost savings of 79% over the compared paint system.
LCC Specification Parameters
The following parking garage parameters were input into the calculator for the LCC comparison:
- Project Size: 500 Tons
- Expected Life-Span: 50 Year Projected Life
- Service Life Environment: C3 (Industrial)
- Structure Type: Simple, 50 - 100' high
- Member Type: Typical Mix Size/Shape
- Paint System: 3-Coat System IOZ/Epoxy/Polyurethane; SP-10 Automated Surface Preparation; 9 mil Minimum DFT
- Time Value of Money: 3% inflation, 2% interest
The initial and life-cycle costs for the paint and galvanizing are shown in the Table below.
|Life-Cycle Cost Comparison
|HDG Life-Cycle Cost Savings: 92%
1 American Institute of Steel Construction (AISC). Innovative Solutions in Steel: Open-Deck Parking Structures.2003.
4 Englot, J. and Davidson, R. "Steel-Framed Parking Garages Take Off at JFK and Newark International Airports." Modern Steel Construction, April 2001.
5 Helsel, Lanterman, and Wissman. "Expected Service Life and Cost Considerations for Maintenance and New Construction Protective Coating Work." KTA Tator, Inc, 2008.