This bridge is a basket-handle arch, which means the two arch ribs are inclined towards each other. It makes the arch more stable and more resistant to transverse loads. The arches are supported by large pile caps that carry the dead load, live load, wind load, etc. and a portion of the thrusting action of the arches. However, tied cables and stiffened girders at the deck level carry most of the thrust.
It looks like a painter's traveler is tucked behind the arch under the deck. You can see the steel rails under the deck that support the traveler. A big expense of steel bridges is keeping them primed and painted. I'm not sure why the large ship is parked under the bridge unless it is also used to help maintain the bridge.
Shanghai's Bridges: Lupu Bridge (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.