Cheaper, faster path led to failure [ Big Dig ]

Boston Globe ^ | December 24, 2006 | Scott Allen and Sean P. Murphy

[SunkenCiv]

Construction engineer John Tsikouras suspected that the salesmen were not telling him the whole story. The men from Newman Associates, a bolt distribution company, approached him in August 1999 and said they wanted his professional advice about a tunnel ceiling that was part of Boston's Big Dig. But Tsikouras said their questions seemed intended to get the Rhode Island engineer's approval rather than his expertise.

Would it be safe to hang the concrete ceiling from 7.5-inch-long bolts? No, Tsikouras said. What if the bolts were 5 inches long instead? "I can ask my mother that one," he replied: Even less safe, obviously. Then, the firm that designed the ceiling sent word through Newman that the ceiling would be far lighter than Tsikouras estimated. Would the bolts be strong enough then? Yes, Tsikouras replied, after making more calculations, "the bolts passed with flying colors."

[patton]

From what I heard, the workers faild to clean out the holes after they were drilled, so the epoxy bonded to the dust.

[herzo]

"From what I heard, the workers faild to clean out the holes after they were drilled, so the epoxy bonded to the dust."

Not an unreasonable observation, but even with a clean hole, how do you assure a 100% bond in an overhead hole?

I'm only happy that it was not my product in that application.

[patton]

Not cheaply. You would have to cure the epoxy under pressure.

[Mark was here]

The failure was undoubtedly NOT in the bolt, rather in the epoxy attachment to the concrete. The 1.5X rule is valid for a threaded fastener into similar materials (steel into steel), but in this application, it does not apply.

I would be interested to know if the whole epoxy plug pulled out of if the threads in the plastic pulled out of the hole. The issue here is not the length of the bolt but the strength of the plastic threads and the strength of the glue to the concrete and dirt. Hind sight being 20/20 I think Studs should of been placed in the concrete.

[MelonFarmerJ]

Have you ever personally drilled overhead into concrete??? Unless they had a special rig, it would take a full day for 1 guy to drill holes just for one panel!! Maybe even more time than that.

This is the core of this whole tragedy. It took thousands of excess (and unnecessary) hours to drill for and set these bolts, therefore more taxpayer dollars for worker payroll, foremen, contractors, and, of course, outstretched political palms on up the line......

[gas0linealley]

You seem unable to comprehend what is being discussed regarding the bolt failure. The stupidity isn't mine.

[IronJack]

There are people at all three levels, local, state and federal, who need to be held to account for this.

And won't be.

[Mark was here]

You seem unable to comprehend what is being discussed regarding the bolt failure. The stupidity isn't mine.

You asked if I was a Big Dig engineer. That was a stupid question. Only a stupid person would think that someone involved with the Big Dig would be disusing the issue on a forum such as this. That is why you asked the stupid question. Tell me why it was a smart question, if you believe it was not a stupid question, then I will revise my opinion of you being a stupid person.

[mrsmith]

"little room for mistakes by the inexperienced construction crew that would erect the ceiling."

My goodness, buried in the article's lies is a little of the truth!

[SunkenCiv]

:')

[SunkenCiv]

Thanks everyone for making this a successful ongoing topic, and Merry Christmas w/ Happy New Year.

http://home.att.net/~hideaway_today/t041/xmas_santa.swf

[Iwo Jima]

"You can't be serious. It achieved it purpose magnificently. Put billions of dollars in the hands of Massachusetts politicians. Your traffic problems were never a consideration.

You alone have grasped the essential point to be made. Those who consider events such as these "failures" fail to comprehend the essential nature of modern day government.

The true objective of 90% of government at all levels is to take money from one group (taxpayers) and transfer it to another group (politically well-connected persons of all kinds). Once the money transfer has occurred, the objective has been achieved. Ergo, there can be no failure of a government project.

This is true not just of "boondoggles" but also of proper acts of a constitutionally limited government such as defense and police function. Properly understood in this manner, the government schools, the war on drugs, social security, Medicare, and the war in Iraq are immense successes. And that will remain true regardless of results. Johnny can't read, drugs are as rampant as ever, social security and Medicare are bankrupting us, the war in Iraq has hit a serious snag -- all is meaningless because actually achieving the purported objective was never envisioned at all.

[xarmydog]

JB Weld is great stuff,but I do not think it wise in this situation.It may very well have been a stronger epoxy,I was being sarcastic.

[sasquatch]

Ping

[FreePaul]

The 1.5X rule is valid for a threaded fastener into similar materials (steel into steel),...

Standard Heavy Hex Nuts are one bolt diameter thick. Bolts used on many high pressure connections are considerably higher strength than the nuts. Standard tests require the bolt to fail in tension before the threads between bolt and nut strip. In applications I am familiar with the stud bolts were threaded into the body of a part one diameter deep. The body material strength was somewhere between that of the bolt and the nut used on the other end of the bolt.

The above has nothing to do with the big gouge problem. Just pointing out that there are many "rules."

[JohnBovenmyer]

This also shows why New Orleans politicians are lobbying hard for another 'successful' levee project. Congressman William Jefferson (D-LA) needs more cold cash.

[Iwo Jima]

Exactly.

[G Larry]

Bet the Mafia cleared 25% of the total cost of the dig.

[herzo]

Perhaps I was not complete enough in my answer. The 1.5X rule was what we used in the die business when installing a Socket Head Cap Screw (170 ksi) into a tapped hole in mild steel (60 ksi). This however is irrelevant to the discussion at hand where a 100 ksi fastener is being held in 4 ksi concrete with a 6 ksi epoxy.

[FreePaul]

...in 4 ksi concrete with a 6 ksi epoxy.

That's if they were close to specs and hoping that there is a connection between concrete and epoxy. I would still like to see the actual design that was used. The photograph shows hex head bolts that must be screwed in to something. Did they anchor a female threaded "nut" in the ceiling?

I've used a lot of concrete anchors around the house. I'm going to put a couple in a masonery wall next week. I would never use them to hang something overhead.

The socket head screws you mentioned are generally of a much higher strength material than hex head bolts or stud bolts. That is if you're careful about who made them. So called "certifications" and "quality assurance" documents don't guarantee good bolts.