Salesforce Transit Center closes due to cracked support beam 16

[hpaircraft]

Salesforce Transit Center closes due to cracked support beam

Not exactly a failure yet, but not a good start, either.

 

[thebard3]

http://www.sfexaminer.com/steel-plates-reinforce-cracked-beams-transit-center-repair-plan/

The fix is underway. Further review of the rest of the structure for potential of further cracking continues.

Brad Waybright

It's all okay as long as it's okay.

 

[BridgeSmith]

Discussing with another engineer in our office, I just realized how poorly this was detailed in several aspects:

1) They cut a hole in the tension flange of a girder at the maximum tensile stress location.

2) They put a kink in a 4" thick plate at the maximum tensile stress location.

3) They welded a stiffener to a 4" thick plate at the maximum tensile stress location.

It took us about 2 minutes to come up with an alternate configuration that would have been be far better for the beam: 2 Beams a few feet apart with a pair of diaphragms running between, sandwiching the hanger strut.

Using a wider and thinner flange would have helped considerably with fabrication, as well.

 

[BridgeSmith]

In reading the ENR article more thoroughly, I noticed they utilized a full-penetration weld to connect the flange sections together at midspan. That would seem nearly impossible to do adequately for a 4" thick plate. The slot for the hanger plate also follows the taper of the hanger plate as it goes from 4" in the middle to 1.5" at the end, making the slot diamond-shaped, which is a poor fatigue detail. Using a continuous flange plate, bent over a long radius curve and using an oval hole around the hanger plate would have decreased the susceptibility of the flange to fatigue cracking.

 

[epoxybot]

Cracked Steel Beams Not Up To Code
San Jose Mercury News: Link

 

[JAE]

Apparently they drilled in the rat holes AFTER the welds were done and then didn't grind them smooth.

The article also mentions that there was a problem with the actual steel material but didn't go much further in explaining that.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[JAE]

Here's a longer recent (March 29) article from ENR.
I wish the included shop drawing sheet images were linked to larger pdf's as you can't really read the markups.

https://www.enr.com/articles/46576-contractors-defend-work-at-troubled-salesforce-transit-center

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[epoxybot]

There is only one of the two drawings (P537BB) available on the TJPA/Skanska site here: Link

If you click on the link it will ask for a sign-in, click the "X" to close the window and the PDF download will pop up.

I don't know if this has been posted "Root Cause Assessment of Fractured Girder Flanges" presentation by LPI Consulting Engineers.
Link

Here is a March 14 Update - It is kind of a puff piece presentation for board members & the Citizens Advisory Committee. Link

 

[StrucDesignPE]

New article about repairs.

https://www.sfchronicle.com/bayarea/article/At-SF-s-Transbay-Transit-Center-it-s-steel-13757725.php

 

[charliealphabravo]

Four-inch thick steel plates to repair and reinforce the four beams have been delivered.

I haven't been following closely enough to know if this is correct, but the plates they show only look to be 2" thick at most if the bolt holes are 1-1/2" diameter. Maybe they mean four 1-inch thick plates?

 

[epoxybot]

Perhaps it is 2 inches top & 2 inches bottom for a total of 4 inches.

 

[epoxybot]

ENR - Ironworkers Install Girder Splints at Troubled San Francisco Transit Hub
Link

 

[BadgerPE]

Has this (and the SF Tower Settlement) thread disappeared from the thread list for anyone else? I can still find it if I search for it, but if I look in "Engineering Failures and Disasters", it doesn't show up. Conspiratorial thoughts are running through my head...

Edit: I had a setting wrong for the display order, so conspiracy avoided.

 

[itsmoked]

That conspiracy 'selection' gets me about once a month. I also have threads marked to email me if there's a response even though I NEVER select that. Gremlins.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[zeusfaber]

This one still shows up on my thread list.

The SF Tower settlement thread has been relegated to the bottom of Page 2 of the list (is it true that there's been no activity on that one for three months, or has something been deleted/had dates changed?)

A.

 

[epoxybot]

There just isn't anything to report on the SF Tower Settlement. The SF Govt. Audit & Oversight Committee hasn't held any further tower settlement hearings. Some of the pile retrofit permits (sidewalk use) must go through SF Planning & then before the SF Board of Supervisors. The SF Planning Environmental Review for the retrofit is still Open.

There wasn't even a mention in the press of the Millennium Tower on 4/18 (1906 Earthquake). Permits for 3 borings, for test piles, for shoring work & the retrofit are all in stasis at the SF Dept. of Building Inspection. Lane closures for the Salesforce Transit Center may have something to do with the lack of any movement on the tower permits. Or possibly it is about money and who assumes risk.

An interesting twist is whether the SF Dept. of Building Inspection will require the retrofit apply Administrative Bulletin AB-082 Link, to the work. They should, if they know what is good for them.

 

[epoxybot]

Transbay Transit Center could get signoff this week for reopen date Link. A meeting will be held in NYC on Wednesday & Thursday. Meanwhile the pedestrian path for the rooftop garden is being completely replaced.

The walkway was originally made from decomposed granite. TJPA officials wanted the path to have a particular shade/color. The subcontractor & GC both told the TJPA that it wasn't recommended and advised against pigment in the mix. Now the TJPA is fighting with the subcontractor over who has to pay.

 

[thebard3]

Maybe the walkway color is important as camouflage....

Brad Waybright

It's all okay as long as it's okay.

 

[epoxybot]

Salesforce Transit Center to reopen July 1..., Sort of.

The rooftop park and grand hall will finally reopen to the public but the Transit Center's main tenant, AC Transit and other Bus Deck level transit services will not return until late summer. Link

 

[Phil1934]

https://www.popularmechanics.com/sc...ansit-center-cracks/?utm_source=pocket-newtab

 

[thebard3]

Phil1934
I'm thinking about taking up vaping now, after seeing the VUSE ad about 25 times while reading that article.

Brad Waybright

It's all okay as long as it's okay.