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Bridge Expert's Opinion - Jan. 9, 2002

 

Dale Gaylord,

I received your email and viewed your Web Site. The setting of your
bridge is spectacular and I can understand why you and your group are
trying to save this bridge. I've viewed the pictures on the Web Site and
have seen several things that would need to be done if the bridge was to
be restored to its original condition. It appears the bridge was widened
and the floor steel beam was replaced with another steel beam. The
original floor beam was an I-Beam and it appears that it was replaced
with a Wide Flange beam. The Wide Flange beam is used today in all steel
structures, and the I-Beam is not produced in the United States anymore.
In the restoration of one of the bridges in the Historic Bridge Park I
purchased I-Beams from a steel warehouse in Michigan that were produced
in Spain. I'll send you an email of a newspaper article that gives some
history of the Wide Flange beam.
It looks like the steel beams that come up from the river, and the floor
beam (which is carrying the stringer beams and deck) is actually the
bridge. The trusses are not working as a truss but more as a handrail. I
would recommend that the bridge be restored to its original width with
an I-Beam.
The channel along the inside of the trusses I would replace with a
replication of a Hub Guard, which you can see on one of the King Bridge
Co., bridge drawings.
I was not able to see in the pictures the Bearing End Pads, the section
of the bridge that sets on the abutments, but I'm sure they would have
to be replicated. From the pictures it appears this bridge could be
restored to its original condition and not take the State of Michigan
treasury to do it.
My method of restoration is to save as much of the original material as
possible, and those bridge members that I have to replace I replicate as
closely as possible to the original. Any rivets that have to be replaced
are not replaced with bolts but with rivets.
I would like to visit your bridge and discuss with you and your group
the restoration of your bridge and what I can do to help you.
I'm sending along a couple of emails that I've sent to engineers and
bridge preservationists on riveting and other subjects.
My wife and I may try to visit the bridge January 20th.
Vern

This email was sent last year to several engineers on riveting.

We are currently restoring the 20-Mile Road Bridge, the second bridge
For the Historic Bridge Park. The 20-Mile Road Bridge required a lot of
Riveting, which gave us an opportunity to develop our skills in
riveting. We will be finishing the first truss this week. It required
over a three thousand rivets in its restoration.

The equipment we're using for riveting is a field-riveting gun called a
Boyer. This riveting gun was the most common field-riveting gun used by
ironworkers and still can be purchased, either used or rebuilt. In my
research in riveting I found many construction companies and fabricators
who still have some field riveting equipment in storage.
(Most historic bridges were shop riveted in sections and than bolted
together in the field)

I've been working with two companies out of Detroit that rebuild or sell
riveting guns. Michigan Pneumatic Tool, Inc. (313-933-5890) has the
largest supply of riveting equipment. Robert Arthur, Vice President, is
the most knowledgeable about riveting tools, and he knows what is in his
vast inventory.

For heating the rivets we use a small three-burner gas-fired forge built
by Mankel Blacksmith Shop in Cannonsburg MI (616-874-6955), just north
of Grand Rapids. This forge is built for farriers and for blacksmiths
forging knife blades, but it is excellent for heating rivets. I've been
working with a construction company in Indiana that is doing restoration
of some of Indiana's Historic Bridges, setting up their riveting
operation. They purchased one of these forges and use it to heat their
rivets.

I purchase my rivets from Jay-Cee Sales & Rivets, Farmington, MI
(800-521-6777). They sell all types of rivets; steel rivets are the most
common. These steel rivets can be purchased in sizes from " to 1 " in
diameter and 1 1/8 " to 8 " in length. Jay-Cee sells a lot of rivets to
the truck and heavy equipment manufacturers for riveting frames. Most
all the riveting done today is cold riveting, and I've talked to a
number of companies that build cold riveting equipment. One of these
companies is located in Jackson, Michigan.

Training someone to rivet is not impossible; anyone who has handled
tools can be trained without a lot of difficulty. Since two retired
ironworkers worked with me on riveting, I have been able to train
several men in riveting. Dennis Randolph, Managing Director for Calhoun
County, recently organized a riveting seminar that was well attended.
Mr. Randolph plans to have more of these seminars, and the fee for these
seminars is reasonable.

Email sent last year to engineers and bridge preservationists on method
of restoration.

First I would like to update everyone on the Historic Bridge Park. As
most of you know, Dennis Randolph, Managing Director of Calhoun County
Community Development, has designated a county park to make a home for
some of Michigan's rare steel riveted truss bridges. The erection in the
park and dedication of the 133rd Avenue Bridge (a four-panel half-hip
pin connected Pratt steel truss 66 foot) occurred last year. This year
on August 10th we erected the 20-Mile Road Bridge (a riveted Pratt Pony
truss built in 1906), the second historic bridge in the park. The
restoration of the 20-Mile Road Bridge required the fabrication of four
new Inclined End Posts and over 3,000 rivets to complete the restoration
of the two trusses. The next historic bridge scheduled for restoration
is a 122-foot Pratt through truss with both forged welded and upset eye
bars for the bottom chords.

Patrick's first e-mail in this exchange (9-6-00) had asked me to cover
disassembly, fabrication, and eye-bars. I'll start with the eye bars, a
component of historic bridges I find the most interesting.

Engineers seem to have a love-hate relationship with the eye bar; some
cringe at the mention of eye-bars and want to see them replaced
immediately, and others have used them at every opportunity. From an
article in The New Yorker (Jan 14, 1991) about the East River Arch
Bridge (or Hell Gate Bridge) crossing New York East River and the use of
eye-bars by Gustav Lindenthal (1850-1935): "Lindenthal carried on a
lifetime love affair with eyebars: he used them in his Pittsburgh
bridges and would have used them in his Hudson River bridge. He
maintained that their lateral rigidity more than made up for the fact
that they cost more than cable."

Mr. Walker described one eye-bar, which has a forge weld connecting an
upset head with the bar, as being fractured. This may have been due to
an improperly made forge weld rather than related to steel failure.
Forge welding an upset eye bar head to a flat bar seemed to be just as
common as forming an upset eye bar out of a single flat stock. We have
in our restoration yard a dismantled 217 foot Baltimore truss bridge
built in 1912, and all the bottom chord eye-bars have upset eye-bar
heads forge welded to flat bar. Some of the forge welds appear to be
separated; I believe this is more a case of an improper forge weld than
steel failure.

The early bridge engineers would prefer that no forge weld be made on an
upset eye bar. J.A.L. Waddell in DE PONTIBUS A Pocket-Book For Bridge
Engineers: "Except in the case of loop-eyes, no weld will be allowed in
the body of the eye-bars."

The eye bars I've repaired for the 133 Ave Bridge were forge welded eye
bars made of steel and had a high level of phosphorus and sulfur. Steel
from NUCOR ASTM A36 has 0.009% phosphorus and 0.040% sulfur and the
eye-bars I repaired had 0.187% phosphorus and .063% sulfur. These levels
of phosphorus and sulfur appear to be typical in the older steels. The
Procedure Handbook of Arc Welding, published by Lincoln Electric:
"Phosphorus in large amounts, increases strength and hardness, but
reduces ductility and impact strength, particularly in the higher-carbon
grades. In low-carbon steels, phosphorus improves machinability and
resistance to atmospheric corrosion. As far as welding is concerned,
phosphorus is an impurity, and should be kept as low as possible. Over
0.04% makes welds brittle and increases the tendency to crack.
Phosphorus also lowers the surface tension of the molten weld metal
making it difficult to control. Sulfur increases the machinability of
steels, but reduces transverse ductility, impact toughness, and
weldability. Sulfur in any appreciable amount promotes hot shortness in
welding, and the tendency increases with increased sulfur. It can be
tolerated up to about 0.035% (with sufficient Mn), over 0.050% it can
cause serious problems. Sulfur is also detrimental to surface quality in
low carbon and low manganese steels."
However, a welding procedure in "Metals And How To Weld Them, Published
by The James F. Lincoln Arc Welding Foundation" suggests this is
possible, recommending low welding currents and fast travel speeds for
welding steel with high phosphorus, and low-hydrogen electrodes for
steels with high sulfur. I found this procedure successful in welding
high-phosphorus, high-sulfur eye-bar steel.

The first step taken to repair the 133rd Ave Bridge eye bars was to
sandblast all the eye bar heads where the forge welds were located. All
of the forge welds were Magnetic-Particle inspected and all indications
marked. Magnetic Particle inspection is a NDT (Nondestructive Testing)
method for locating discontinuities in magnetic material. A scarf joint,
a form of a butt joint, is used for forge welds. This means a
Magnetic-Particle indication discovered on one side will appear
displaced on the backside. The next operation was to lightly grind the
Magnetic-Particle indications. Most appeared to be the overlapping end
of a forge weld, and the indications would quickly disappear with
grinding, suggesting that there was no separation in the rest of the
forge weld. (People who are not familiar with grinding may say that the
grinding has obscured the indication, but this could only happen if the
steel and the grinding disk are extremely hot.) To determine the depth
of those indications left after grinding, the Liquid Penetrant
inspection method was used. This NDT method I've used as a foreman in
charge of welding operations that required compliance to American
Welding Society (AWS) standards. This NDT method is an economical and
effective method for inspecting the back gouged root for Complete Joint
Penetration Groove Welds. The type of discontinuities that had to be
repaired in the 133rd Ave Bridge eye bars was similar to a Lack of
Fusion discontinuity in an improperly made electric arc weld. With the
information in "Metals And How To Weld Them," I developed the following
welding procedure for repairing the eye-bars on the 133rd Ave Bridge;
this involved making groove welds and pad-welding areas of
loss-of-section due to rust.

Mag Particle all forge welds.
Purchase Low Hydrogen electrodes 1/8 and 3/32 in hermetically sealed
containers and store in a holding oven at 250 degrees (AWS).
Determine with dye penetrant the depth of discontinuities in the forge
welds, then grind a groove and prepare for welding.
Preheat the area of the groove at 250/300 degrees (AWS).
Weld with 1/8 or 3/32 E7018 electrodes.
Once the weld is cool, grind and inspect with Dye Penetrant for hot
cracking. (None was discovered in the 133rd Ave Bridge welds.)
After the loss-of-section areas were welded, a heat treatment was
performed on all the eye-bars; this consisted of heating the eye-bar
head at 600 degrees and an hour later at 300 degrees.
A final Dye-penetrant test was performed on all the eye-bars to detect
any delayed cracking. (None observed.)

I have inspected many Historic Bridge repairs that were made over its
lifetime and the electrode that road crews seem to prefer was E6010.
This not a Low-Hydrogen electrode and was designed primary for the Root
Weld in pipe welding, and is not permitted in bridge code welding. This
electrode should be avoided in any historic bridge repairs.
If it's decided to replace the eye bars I would suggest having them cut
(burned) out of A36 plate. Any steel warehouse that does production
plate burning will have equipment that will be able to cut out an eye
bar shape with very little distortion. The eye bar length should be cut
perpendicular to the mill rolling direction.

Disassembling an old Historic Bridge is not as painful as some
contractors may imagine. I had one constructor, from a very reputable
company who has built many bridges in Michigan, tell me their experience
with old bridges was to cut them up for scrap. They were at a loss on
how to disassemble a Historic Bridge for restoration. But once I
introduced their crew to equipment that I've used for disassembling
historic trusses, equipment I've used for years as a steel fabricator,
they were surprised at how quickly the disassembling went. A year later
I had a chance to talk to the project manager on the job and he told me
the cost for disassembling the bridge, a 122 foot Pratt Through Truss,
was a lot less than they anticipated. The equipment this crew used for
disassembling the truss was a demolition tool referred to as a rivet
buster from Chicago Pneumatic for removing rivets, and MAPP-Oxygen
heating equipment for heating nuts on U-Bolts, and Chord pins for
removal. Other equipment I've used for truss disassembly where rivets
have to be removed is the air-carbon arc process, and cutting tips for
the oxygen acetylene torch. These tips are especially designed for metal
washing; this process and the other processes do little or no damage to
the parent metal. The air-carbon process is a very efficient process for
back gouging AWS Complete Joint Penetration groove welds, removing
defective welds, and removing rivets. This process I'm convinced was
invented by an engineer who hated weldors, because it is very noisy,
hot, and produces a lot of hot sparks, but a process no steel fabricator
would do without.

Air-carbon arc cutting and gouging is an arc cutting process that severs
or removes metal by melting it with the heat of an arc struck between a
carbon-graphite electrode and the base metal. A stream of compressed air
blows the molten metal out of the kerf or groove. In our restoration
work, when the arc was struck against the rivet it melted the rivet head
and the air blew the molten rivet away. Very little damage was done to
the parent metal.

I've tried to keep the marking process simple by first starting out with
paint spray can, and painting the main members of each truss with a
swath of color. One truss is painted red and the other yellow. On the
Inclined End Post and Top Chords with the spray can I'll write direction
marks with designated truss color. On smaller truss members, in addition
to the paint, I will tag it with metal tags identifying the part and
location. After the paint marking is complete I take a number of
pictures of the truss marking and draw a small sketch of the bridge
markings.

Vern Mesler


THE NEW YORK TIMES ARTICLE,
SATURDAY, OCTOBER 21, 1995


Farewell to a Mill That Shaped the Modern City


Bethlehem Pa, Oct 18 The George Washington Bridge came from here. So did
the basic structure of the Waldof-Astoria Hotel, the chase Manhattan
Building Madison Square Garden, the Metropolitan Opera House and the
Time & Life Building.
All were build from steel made and shaped at the Bethlehem Steel
Company's mill here on the banks of the Lehigh River. In fact, the
single-piece H-shaped girder- the building block of skyscrapers- was
first produced here in an early 20th century financial gamble for
technology that was as daring for its time as the latest silicon chip
plants are today. "If we go bust we'll bust big" Charles M. Schweb the
president of Bethlehem remarked a few years after the turn of the
century as he was raising millions of dollars for the experiment plant.
(On Friday, the last red-hot heavy-duty beam was produced and rolled
into shaped. The old heavy-duty beam mill then fell silent.)
In a few weeks the last blast furnace and related equipment will be shut
down and basic steelmaking will cease in this valley for the first time
since 1873.
When it does a way of life that has long been in decline will come to an
end. "My father and grandfather worked here", said Mike Martin a
Supervisor at the mill, "This place has a history and a soul that the
new mills do not."
It is the kind of place where a man with two levers controls a 20,000
horsepower steam engine that drives the steel through rails weighing six
to seven tons squeeze it into shapes, for all the force involved, it is
a surprisingly delicate job.
"If he waits until the bar is fed in to start the rolls he's likely to
stall the engine," said Bill Wilds, the senior supervising engineer for
the mill and a second generating steelmaker.
"But if he starts it too soon, it's likely to be moving too fast and may
break the bar."
There will be no more bars. Mr. Wilde will be moving on to a small
finishing steel operation, which will remain to shape smaller beams from
steel imported from Steelton PA. But for most of the 1,800 workers
facing shutdown, their time with Bethlehem is over.
Company officials described the closings - which were announced nearly a
year ago - as a rational adjustment to an economy that is not building
many of the tall office building that require the jumbo beams.
"Companies today are decentralizing," said Timothy Lewis, the manager of
Bethlehem's structural operations, "You don't need Sears Towers anymore."
Prodded, they will concede that the rise of efficient mini-mills, like
those operated by the NUCOR Corporation and the Chaparral Steel Company,
has made it difficult for older companies to compete in a market where
price is paramount.
The new mills rely on many fewer workers and a simpler production
process than the old companies. They also do not carry the heavy health
care and pension expenses that traditional steelmakers do.
"There are many companies capable of supplying this product," Curris H.
Barhette, Bethlehem's chairman, said, "We have to make our investments
wisely and we decided to put our investment dollars elsewhere." He said
the structural division had been unprofitable.
Until Mr. Schwab came along to take a chance on the turn-of-the-century
technology with his investment dollars, H-shaped steel beams were
riveted together from plates and angles, limiting their strength and the
height of the buildings that could built.
Henry Grey was an English-born inventor who developed a process for
rolling wide-flange beams of uniform thickness in the late 1880's. But
he was at first unable to persuade any American steel companies to adopt
his technology directly.
After a mill built in Germany and the process from it became successful,
Mr. Schwab decided to get into the business. In 1907, he began building
the mill. The first beam was rolled in 1908 and a new generation of
skyscrapers was designed by engineers and architects who could simply
specify the size of the girders they needed. They were called Bethlehem
sections.
Steel companies do not rush to replace equipment that can be repaired
and Mr. Grey must have been a good engineer; some of the equipment
installed in the mill in 1907 was still operating this week.
The single-piece H-beams - bigger and broader than the better known
I-beam - were a huge economic success and helped build Bethlehem into
the nation second-largest steel company, after United States Steel.
Indeed, the company's symbol includes a representation of a Wide-Flanged
beam.
The irony is not lost on the workers. "This mill built Bethlehem Steel,"
said Radwan Jarrow, who prefers to be called Ed. "A lot of us are
feeding betrayed as a community."
Unhappy feeding aside, the workers were producing steel flat out in the
days before the closing. Word that the mill would be shutting down had
produced a last-minute flurry of orders.
"They say there are no orders for big beams, but that's all we have been
rolling," SAID Tim Betz, who operated a large motorized saw that cut the
beams to lengths, specified by customers. "And we are going to produce
the beast products we can up until the last minute."

 

 

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