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Thank you, M.Harris! etc....
Author: Margaret (SP fan)
Date: 05-27-2013 - 00:26
M. Harris:
Thank you very much for that very informative answer
to my question. replies such as yours are the reason
I enjoy this forum so much.
What matters most is the load on each bridge element.
Very heavy trucks put more stress on a bridge than do
lighter trucks.
Ken:
I, too, was on the bridge then, during that 1987 Bridge Walk.
More on that later.) The deck deflected 10 feet -- and there
was a 17-mph wind blowing at the same time. Not a problem --
that bridge is designed to withstand much more than that.
According to the San Francisco Examiner of May 26, 1987,
Charles Seim, former state of California Department of
Transportation supervising bridge engineer, was also on the
bridge during that famous 50th anniversary Bridge Walk. He said
he calculated there were about 40 people per linear foot of the bridge
that day. This gives a live load of about 6,000 lbs per linear foot.
Rush-hour traffic gives a live load of about 2,200 lbs per linear foot.
Seim reportedly said he was not worried about the load all those people
put on the bridge, as it was much less than what the bridge was
designed to bear. According to those figures, there were around
a quarter of a million people on the bridge that day, not one million.
(I think the one million figure is accurate for the number of people
at the entire celebration.)
People who were on the bridge during that 1987 Bridge Walk reported
the vertical suspender cables were stretched "as tight as harp strings".
This was mostly near the middle of the bridge. I remember someone
saying later that they saw the vertical suspender cables nearest the
towers flapping loosely!
In contrast to some reports of panic, I saw and experienced nothing
of the sort. It absolutely amazed me that people were as calm as
they were. But, then, I only got as far as the part halfway between the
south tower and the south end of the deck. I don't have any idea how
people acted in other areas of the bridge. I, too, stayed for the
fireworks. Got a great, but blurry, photo of the shadow of one of the
towers on the smoke from the fireworks.
People really do weigh more than cars when crammed together like that.
We made history that day -- quite unintentionally. Thank heavens Seim
was right because the designers who built that awesome bridge built it too
very high safety standards.
Margaret
Thank you very much for that very informative answer
to my question. replies such as yours are the reason
I enjoy this forum so much.
What matters most is the load on each bridge element.
Very heavy trucks put more stress on a bridge than do
lighter trucks.
Ken:
I, too, was on the bridge then, during that 1987 Bridge Walk.
More on that later.) The deck deflected 10 feet -- and there
was a 17-mph wind blowing at the same time. Not a problem --
that bridge is designed to withstand much more than that.
According to the San Francisco Examiner of May 26, 1987,
Charles Seim, former state of California Department of
Transportation supervising bridge engineer, was also on the
bridge during that famous 50th anniversary Bridge Walk. He said
he calculated there were about 40 people per linear foot of the bridge
that day. This gives a live load of about 6,000 lbs per linear foot.
Rush-hour traffic gives a live load of about 2,200 lbs per linear foot.
Seim reportedly said he was not worried about the load all those people
put on the bridge, as it was much less than what the bridge was
designed to bear. According to those figures, there were around
a quarter of a million people on the bridge that day, not one million.
(I think the one million figure is accurate for the number of people
at the entire celebration.)
People who were on the bridge during that 1987 Bridge Walk reported
the vertical suspender cables were stretched "as tight as harp strings".
This was mostly near the middle of the bridge. I remember someone
saying later that they saw the vertical suspender cables nearest the
towers flapping loosely!
In contrast to some reports of panic, I saw and experienced nothing
of the sort. It absolutely amazed me that people were as calm as
they were. But, then, I only got as far as the part halfway between the
south tower and the south end of the deck. I don't have any idea how
people acted in other areas of the bridge. I, too, stayed for the
fireworks. Got a great, but blurry, photo of the shadow of one of the
towers on the smoke from the fireworks.
People really do weigh more than cars when crammed together like that.
We made history that day -- quite unintentionally. Thank heavens Seim
was right because the designers who built that awesome bridge built it too
very high safety standards.
Margaret
