Available at: http://digitalcommons.calpoly.edu/theses/708
Date of Award
MS in Architecture - Architectural Engineering
Quantifying the Life Cycle Benefits of Performance-Based Design in Sustainable Design
For this thesis, a method is developed and tested for use with performance based design to quantify the sustainable and financial benefits of designing buildings to a structural performance level higher than Life-Safety. This paper starts to answer the question, “which would be a better investment: build structures to a performance level of Immediate Occupancy (IO) with the likelihood of less damage and downtime after an earthquake or continue to build to the building code’s implied minimum performance level of Life-Safety (LS)?”
An ASCE 7-05 designed base model building (six-story, steel moment frame, office located in San Francisco) was designed to meet the minimum requirements of the LS or stricter code requirements of the IO performance objectives, respectively. Performance levels were verified using the ASCE 41-06 linear static procedures and ETABS models.
The overall cost and cost difference for building the two structures were determined using RSMeans reference manuals. The structural upgrade cost from LS to IO is roughly 1.6% of the $33.4 million initial building cost for a total of approximately $500,000.
The financial damage caused to the two buildings due to a series of earthquakes was determined using the ATC-58 Guidelines and the modeling capabilities of its companion software Performance Assessment and Calculation Tool (PACT). Due to PACT’s work-in-progress status and limited quantity of fragility curves representing building components, results are questionable and expected to become more fine-tuned as the software develops and there is an increased availability of fragility curves.
Using the PACT program, the difference in annualized loss between the IO and LS buildings was determined to be roughly $40,000. This is equivalent to a 2009 present cost of $590,000 over a 50-year building lifespan. By designing the building to an IO performance level, the owner potentially saves 18% ($590,000 loss to future seismic damages/ $500,000 cost to upgrade) over the life-span of the building. As buildings begin to incorporate state-of-the-art, more expensive and efficient components, designing higher performing structures to protect these upfront costs will prove more beneficial than repairing the components at a future date. Considering building downtime and loss of life would increase the value of savings and provide an additional incentive to design a structure directly to a higher performance level.