I accidentally signed up for a course in advanced indeterminate structures in
the first quarter of graduate school at Georgia Tech. It was blandly and
misleadingly titled "Construction Methods" but actually was the calculating of
wind loads on multi story structures with loads in two or three directions. I'd
been out of school for 5 years in Vietnam, etc. and had been worried about
other more pressing things so was desperately trying to get up to speed so not
to lose my Army scholarship. There were 5 of us in the course: three Chinese
guys who had graduated with honors that year, a former Marine who had just
gotten off active duty and me. The Marine and I were lucky to get out with a
complementary C, I don't think anybody made better than a B in that course.
Accurately calculating those loads in addition to trying to predict exactly
what loads to design for is complex and takes not only skill but experience and
maybe a bit of luck. Other than wood design I've stayed away from structures
courses after that.
-----Original Message-----
From: Didi Pei <didi@xxxxxxxxxx>
To: pa64@xxxxxxxxxxxxx <pa64@xxxxxxxxxxxxx>
Sent: Fri, May 21, 2021 6:47 am
Subject: [pa64] Re: Bet they'll hire Pei Architects next time
#yiv9486612523 #yiv9486612523 -- _filtered {} _filtered {}#yiv9486612523
#yiv9486612523 p.yiv9486612523MsoNormal, #yiv9486612523
li.yiv9486612523MsoNormal, #yiv9486612523 div.yiv9486612523MsoNormal
{margin:0in;font-size:11.0pt;font-family:sans-serif;}#yiv9486612523 a:link,
#yiv9486612523 span.yiv9486612523MsoHyperlink
{color:blue;text-decoration:underline;}#yiv9486612523
span.yiv9486612523EmailStyle19
{font-family:sans-serif;color:windowtext;}#yiv9486612523
.yiv9486612523MsoChpDefault {font-family:sans-serif;} _filtered
{}#yiv9486612523 div.yiv9486612523WordSection1 {}#yiv9486612523 All tall
buildings sway. The trick is to control it. We subject all tall building
designs to in-depth wind tunnel testing. The problem here was most likely what
we call vortex shedding wherein under rare circumstances oscillating winds can
create forces at the upper corners (which can be reduced by careful design)
resulting in vibrations. Sometimes we end up cutting or otherwise modifying
these important upper corners to reduce the vortex effect. Is that what you
were talking about? Chinese structural engineers are quite good, but this
phenomenon is more difficult to detect and requires experienced engineers
working with experienced wind tunnel testing. I don’t think this was a case of
cutting corners but more inexperience. This building was not very tall. BTW
there are certainly more tall buildings built in the last 20 years in China
than in rest of the world combined. From: pa64-bounce@xxxxxxxxxxxxx
<pa64-bounce@xxxxxxxxxxxxx>On Behalf Of dmarc-noreply@xxxxxxxxxxxxx
Sent: Thursday, May 20, 2021 9:34 PM
To: pa64@xxxxxxxxxxxxx
Subject: [pa64] Re: Bet they'll hire Pei Architects next time Office
building at 28 State in Boston used to sway in high wind. On top floor you
could see the chandelier sway way back and forth. Then you realized it was a
pendulum and the whole building was moving around it. Cross braced in gut rehab
in early 90s. Engineers are the key and China seems to cut important corners in
many of these buildings
-----Original Message-----
From: rhelkins <dmarc-noreply@xxxxxxxxxxxxx>
To: pa64@xxxxxxxxxxxxx <pa64@xxxxxxxxxxxxx>
Sent: Thu, May 20, 2021 12:33 pm
Subject: [pa64] Bet they'll hire Pei Architects next time State Department
Issues Warning After Chinese Skycraper Wobbles Violently In Mysterious Incident
| ZeroHedge
