BRIDGES AND
TUNNELS OF
ALLEGHENY COUNTY,
PENNSYLVANIA
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Article Index
HAER
Smithfield Street Bridge, Pittsburgh, PA
01 Cover Page
02 Foreword
03 Ferries
05 Monongahela
Bridge and
Fire
12 Masonry
17 Removal
of Old and
Erection of
New Bridge
18 Flooring
19 Ornamental
Towers and
Painting
22 Alterations
23 Footnotes
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Smithfield Street Bridge, Pittsburgh, PA Historic American Engineering Record PA-2 page 20
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Loads and Unit Strains Beginning from the north end, there are: 1. One 40 foot span, six equal plate-girders, proportioned for a live load of 10,800 pounds per lineal foot of bridge. 2. One 81 foot span, six equal plate-girders, proportioned for a live load of 9,000 pounds per linear foot of bridge. 3. One 87 foot span, six equal plate-girders, proportioned for a live load of 9,000 pounds per lineal foot of bridge. 4 & 5. Two channel spans, 360 feet each, two equal Pauli trusses of steel and floor construction of iron, proportioned for a live load of 4,500 pounds per linear foot of bridge and in addition a concentrated load of 40 tons on a 20 foot wheel base for each track; of these loads the sidewalks were assumed to carry 100 pounds per square foot. 6. One span, 88 feet 3 inches, six equal plate-girders. 7. One span, 84 feet 9 inches, six equal plate-girders. 8 & 9. Two spans, 60 feet each, six equal plate-girders in each. All of these plate-girder spans proportioned for 9,000 pounds live load per linear foot of bridge. The wind truss and lateral bracing under the floor is proportioned for a wind force of 400 pounds per lineal foot of bridge. The above live loads, in addition to the load of the superstructure in the different spans, produce no greater strains per square inch of useful metal areas than: IRON 8,000 pounds in compression flanges of all plate-girders, floor beams, stringers, etc. 9,000 pounds in tension flanges of all plate-girders, floor beams, stringers, etc. 8,000 pounds tension in suspenders and hangers of channel spans. 4,000 pounds shear in iron web-plates. 12,500 pounds bearing strain on iron in rivet and pin-holes. FOR STEEL 9,800 pounds to 13,200 pounds in compression members. 15,000 pounds in steel eye-bars. 10,000 pounds shear on steel rivets and steel pins. 20,000 fibre strain on steel rivets and pins from bending-moment. 18,000 pounds bearing strain on steel in rivet and pin-holes.
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Introduction Last modified on
30-Sep-99
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