Call it a wish list or, if you’re feeling jaded, the biggest insurance policy on projects today – but what if the increasingly popular 100-year service life requirement is actually not that accurate to be “guaranteed”?
The concept has brought additional focus to the long-term performance of infrastructure, but the AEC industry hasn’t defined “100-year service life” or given engineers and designers consensus-based standards for achieving that goal. It’s important that an appropriate tool is developed with industrywide participation and agreement.
Such is the message of Oscar Antommattei, MS, PE, FACI, a senior concrete engineer and engineering manager at Kiewit , who explains his position here. He’ll expound more fully at the Infrastructure Imperative Conference Nov. 13 - 15 in Cleveland.
Concrete Construction (CC): What’s the sticking point vis-à-vis the 100-year service life concept?
Oscar: Everyone has a different idea of what “100-year project” means. Consensus-based standards or guidelines don’t exist to determine what’s going to be used for estimating, designing, and building a project like that. That’s the challenge.
Is it true? Is it not true? There’s no way to answer these questions without a standardized way to verify more accurately the certainty of those predictions. And from a more practical standpoint, nobody who’s alive today is going to be here in 100 years.
CC: If there’s no uniform code for defining and achieving 100-year service life, doesn’t that make bidding difficult (to say the least)?
Oscar: Absolutely. You might be a builder who knows too much, and that can be a disadvantage.
Why? Because there’s no standard. No rules. And you know more about what will be involved.
The other guy is going to say, “I can do it this way, and I can meet, for example, the International Federation for Structural Concrete (FIB).” But the owners developing these specifications might not know the European code well enough to tell you where they want you to be. Most people in North America are more familiar with American Concrete Institute (ACI) standards, but ACI hasn’t developed a comprehensive standard.
A project specification may say 100-year service life, but what does that mean?! It’s like saying, “I want blue.” One bid gives you baby blue; another, navy blue. “Hey – all you said was ‘blue.’”
At the end of the day, we’re all working from a different playbook.
CC: Isn’t FIB – the code developed in Europe – a reasonable place from which to base 100-year design?
Oscar: It’s not that simple. Extrapolating European codes in North America may not be workable or applicable for all cases. Projects and industry views are so different, from the way they’re procured, designed and built to the social environment. Durability expectations aren’t necessarily the same, and that’s very important.
Some people are trying to use FIB, as well as other analytical and modeling proprietary concepts, here; but we need to determine if or what components of an approach are relevant or not in the U.S. market. There are many different views and considerations to ensure the right approach is implemented for long-term durability assessments in North America.
The other thing to think about is the way we procure projects in North America. While a value-based approach is being used more frequently, a traditional low-cost approach isn’t well-suited for long-term performance such as 100-year service life.
CC: If there’s no consensus-based code and no true verification – and yet these things are written into contracts – are we stockpiling trouble for future generations?
Oscar: It depends on how much credence is put into 100-year performance. The industry has long been building work that has a long life—40, 50, 60 years, sometimes even longer. It’s putting the label and expectation of 100 years on it that causes problems, especially without a consensus-based standard.
The industry just keeps procuring projects without a standardized process or standardized verification on what exactly 100 years means. There have to be standards that clearly describe the approach needed to achieve this, or at least to have a level playing field.
The good thing is that people are discussing it.
CC: Is anyone moving the ball to get these much-needed standards created for the U.S.?
Oscar: Many organizations have published papers about 100-year performance, but those aren’t consensus documents. So far, it’s just a wish list from a single perspective. You don’t see in-depth involvement from design and construction practitioners or from concrete producers or materials manufacturers, the people who are going to implement all that theoretical knowledge.
I’m co-chair of a recently established ACI task force that will start developing standards for design and construction of durable structures. We hope to provide tools that close the knowledge gap and establish a more consistent approach to the durability and service-life concepts.
CC: If ever there was a task that needed force, I’d say it’s this one!
Oscar: Yes, and at least there will be a level plane for everyone so you can see where the consensus basis is and work from there.
CC: Can’t today’s sophisticated technologies help with the accuracy of predicting 100-year longevity?
Oscar: Many researchers are pushing technology to a level where you start getting some predictions. However, accuracy must be verified and calibrated to ensure you can do it consistently and reliably. Who can say something will last 100 years – you’d have to wait 100 years to check. Without parameters in place, uncertainty will exist.
You can put together three different models and they’re going to predict three different things. How is that even acceptable?! Which is the best one to stand behind? At this point, no one knows. A lot of judgement is required without any standardization.
Some owners see the most expensive and difficult proposal and say, “Oh, that’s the one.” But you don’t know that. It doesn’t mean anything until there is consensus and it’s been standardized and verified.
As engineers and practitioners, we need to make sure we have the right tools and technologies available to everyone. We must look at the big picture and not go into the weeds of 100.2 years versus 98 years, for example. Current tools aren’t that accurate or exact to establish such specific values in a reliable way.
CC: What does your crystal ball say about the future of 100-year durability requirements?
Oscar: Consensus is coming. Hopefully, in 20 years, we’ll have different procuring practices and different ways of estimating and designing work.
The building-constructing work is going to change, too. You’re going to have to have more robust quality-control practices.
There needs to be more effort in the pre-bid period, too. Testing procedures take a long time – currently, there’s no way you can procure projects without getting into some type of testing pre-bid so you can understand what you’ve got and design for it.
Eventually, you’ll be able to guarantee your long-term performance with a sounder approach that is backed by more reliable data and not just subjective conjecture.