Tower cranes need counter-weights to keep from tipping over- that's what the
red brick is for.
is a deck truss- the load (cars, people etc.) pass on top of the truss. I used single wide beams, connected at the joints
8-32 machine screws. The bottom middle member is a string
tensioned with a turn-buckle.
The live load is approx. 100lbs. This puts tension on the line (string) on
the bottom. I'll use the Method of Sections to compute the amount of tension on the string.
In a through truss, the live load passes through the truss. I only put around
50 lbs. on the deck.
In this lift bridge, the line is attached to the end of the deck, then goes
over a sheave (pulley) high up on the tower, and then down to the windlass.
Here the line goes over a pulley mounted lower down on the tower.
The lower angle means that it will take more force to raise the deck of the bridge.
Enter content here
In a cable-stayed bridge, the deck is supported by cables (string in this
case) that go in straight lines from the towers to the deck.The main span (the distance between the 2 towers) is almost 6ft.
Suspension bridges differ from cable-stayed bridges. The 2 main
cables rest on top of the towers, curve down between the towers and then attach to the anchorages. The deck is held
up by the "suspenders" the short black lines that hang down from the main cables and connect to the deck.