Without expansion joints the restrained SSTC is a threat to public safety

Instead of holding public meetings so that federal, state and local taxpayers who paid for the "monumental debacle" Silver Spring Transit Center could ask questions and comment on the public record, Montgomery County's David Dise, Isiah Leggett, George Leventhal, Roger Berliner, et al ran their collective mouths to the news media (print, TV, radio, internet) for two and a half years saying that the "SSTC will absolutely be safe" (an absolutely absurd statement since nobody can predict the future) and that Montgomery County is not to blame for any of the Silver Spring Transit Center's serious design, construction and inspection flaws, which is equally absurd. 

Since March 2013 when the extensive cracking and other design, construction and inspection flaws became public, no one from the news media has bothered to ask Montgomery County, or WMATA, why the SSTC doesn't have expansion joints located at least every 100 feet---a WMATA requirement. 

The average coefficient of expansion/contraction for concrete structures is approximately 0.0000055 inch change in length per inch of total length per degree temperature change. Temperatures in Washington DC can reach above 100 degrees Fahrenheit in the summer (with the temperature of the surface of the SSTC's exposed concrete deck being tens of degrees greater) and below 20 degrees Fahrenheit in the winter. The 315 ft. wide by 580 ft. long SSTC expands and contracts 1.66 inches and 3.06 inches respectively for an 80 degree change in temperature.

Not long after the SSTC's cracking became public, it was reported that a person from builder Foulger Pratt said that "the SSTC is like a tightly wound snare drum". This is consistent with KCE's report that says that the SSTC doesn't have any expansion joints. Built without expansion joints, the SSTC is massive, monolithic, restrained and cracked. 

Had the massive SSTC been built with expansion joints, as standard construction practice and WMATA design and construction standards require, then it would be unrestrained, and the resulting smaller "pieces" (separated by expansion joints) would be able to absorb changes in temperature without unduly stressing and cracking the entire structure. (Smaller "pieces" mean smaller changes in length for the same temperature change.)

But, the SSTC wasn't built with expansion joints. Slabs, beams, girders and columns were constructed monolithically; it is restrained. An 80 degree change in temperature stresses and cracks the jointless SSTC as it tries to expand and contract.

Can you imagine the force on the restrained slabs, beams, girders and columns when the 315 ft. wide by 580 ft. long SSTC expands and contracts 1.66 inches and 3.06 inches respectively? Enough to make concrete crack! Have you ever tried to crack a 12 inch thick piece of concrete? It takes a LOT of force! The SSTC is indeed "a monumental debacle" and "like a tightly wound snare drum"! 

It should be noted that the 80 degree temperature change for Washington DC used for these calculations is well within the 121 degree difference between the record high of 106 and record low of -15 for Washington DC. (U.S. state temperature extremes - Wikipedia, the free encyclopedia) 

The heating and cooling cycle never ends--daily, monthly, yearly--generating new cracks for moisture to penetrate, freeze and loosen concrete, potentially falling on unsuspecting commuters. Without expansion joints the restrained SSTC is a threat to public safety.

a comment to a Washington Post article:

a comment to an ENR article: 

Since March 2013 the news media (print, TV, radio, internet) have failed to get to the bottom of the Silver Spring Transit Center debacle. A modicum of skepticism along with a few simple questions (and followup) to Montgomery County and WMATA would have uncovered the truth:

to Montgomery County and WMATA: Why doesn't the SSTC have expansion joints like other large outdoor structures (parking garages, stadiums, bridges, etc.)?

to WMATA: Given that the SSTC was supposed to have been designed and built to WMATA standards, and that WMATA was paid to review the design and construction, how could WMATA miss, for nearly a decade, that the 315 ft. wide by 580 ft. long SSTC doesn't have any expansion joints, particularly when WMATA's own design and construction standards require expansion joints to be located no farther apart than every 100 ft.?

to Montgomery County and WMATA: Given this major design and construction deficiency (total lack of expansion joints and the cracking that will continue to happen because of it), and other serious design, construction and inspection flaws documented in the reports that you (Montgomery County and WMATA) commissioned, how can you tell the public that "the SSTC will absolutely be safe"?

to Montgomery County: Given that the SSTC is Montgomery County's project, and that Montgomery County is responsible for reviewing, approving, and permitting all construction in Montgomery County, both private and public, and given that you handpicked engineer Parsons Brinckerhoff, builder Foulger Pratt and inspector/materials tester Balter Company without the normal competition that accompanies selecting private companies for most public works projects, and given that Montgomery County was construction manager for the SSTC with a team of full-time county employees onsite during construction, how can you say that Montgomery County doesn't bear any responsibility for the SSTC's serious design and construction flaws?

One would think that with hundreds (if not thousands) of print, TV, radio and internet reports since March 2013 that one of the scores of reporters would have thought to ask these simple questions and to follow up on the obvious "smoke" coming from both Montgomery County and WMATA.

Without expansion joints the restrained SSTC is a threat to public safety.

The fundamental responsibility of an engineer is to "hold paramount the safety, health and welfare of the public."
Code of Ethics | National Society of Professional Engineers

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