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The Brooklyn Bridge Splices

                                                    by Don Sayenga
         Metal fatigue is defined by Britannica as a weakened condition induced in metal
         parts of structures by repeated stresses or loadings, ultimately resulting in fracture
         under  a  stress  much  weaker  than  that  necessary  to  cause  fracture  in a  single
         application. Engineers and scientists don’t fully understand how this happens.
         To avert disasters it is normal to design metal structures five or six times stronger
         than needed. So far, this approach seems to work.

              he  big wire  suspension  bridge   cables  themselves  remain  essentially   common is the length of the main span
              over the East River, which  has   as they were when the bridge opened   hanging  in  plain  sight  in  open  space.
         Tbecome known everywhere as the    for business. They are unique. No oth-  In the case of the Brooklyn Bridge, this
         Brooklyn Bridge, was the world’s first   er bridge ever has been built with the   open span distance  is  usually given
         major structure designed and built   same kind of main cables.        as slightly more than 1595  feet. It  is
         with  steel  wire.  Its four  main  cables                            a measurement easily grasped by the
         went  into service  in  May 1883.  They   The Biggest Bridge          general public. The Guinness  book (if
         are still there as the primary support   Very little publicity has been given to   it had existed) would have placed the
         holding up the suspended structure   the details of why the cables are so spe-  Brooklyn Bridge main span at the head
         which  weighs more than 6000 tons.   cial. Possibly this is because the giant   of the list in 1883. To make a modern
         This means each of the main cables   stone  towers  holding  them in  the  air   comparison,  consider  the  Akashi  Kai-
         has been carrying a load in excess of a   were themselves beyond comparison at   kyo bridge near Kobe, Japan. It is sup-
         thousand tons for more than 133 years.   the time. They attracted all the atten-  ported by two steel wire cables carry-
         Although the burden  they carry has   tion.  There  are  several  ways  of  rank-  ing a main span of 6532 feet. Editor’s
         been  reconfigured  several  times,  the   ing suspension bridges but the most         continued on page 18

         Brooklyn Bridge in the 1880s: New York City (foreground) was the largest city in the USA. Brooklyn (background) was the third largest. In 1864, two
         Brooklyn engineers proposed a way to connect the two cities with a steel suspension bridge. There were no tall buildings in either city at that time.
         16     Wire Rope News & Sling Technology   February 2017
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