The steel truss was placed by contractor China Major Bridge Engineering.
The 6.15km-long bridge will have 41 spans and will carry road traffic on its 22m-wide upper deck and a railway on its lower deck.
Senior politicians including prime minister Sheikh Hasina and transport minister Obaidul Quader joined in the celebrations marking the installation of the first span. Quader described the event as meaning that the bridge is now a visible reality.
