Dynamic measurement and overall bridge rating for the existing River Niger Bridge in Onitsha, Anambra State - Nigeria
Engineering design for dynamic measurement as well as overall bridge rating for the existing River Niger Bridge in Onitsha, Anambra State.
The bridge, designed in 1961/1963 and built by Dumez Construction - France in 1963/1965, consists of No. 4 continuous steel truss girders: lateral girders consist of No. 2 spans, each of which is 90 m long; central girders consist of No. 4 spans, each of which is 130 m long.
The elevation scheme is symmetrical. On each half of the bridge, fixed supports are located between the first and the second span and between the fourth and the fifth span, while expansion joints are located between the first and the second girder and in the middle of the bridge. The slab of the deck is made of precast concrete elements and reinforced concrete cast in situ.
There is full interaction between the concrete slab and the steel deck.
The No. 13 piers are in reinforced concrete and they consist of No. 2 columns with a variable rectangular section. Columns are connected through a pier cap and a lower diaphragm.
The scope of work consists mainly in:
- the study of the river hydraulics and hydrology with particular attention to the erosion evaluation, sand banks movements and flooding
- an overall assessment in order to determine the preservation conditions of the bridge structures and to verify the static and dynamic behaviors of the bridge
- non-destructive tests on materials (steel and concrete), static load tests and dynamic tests
- comparison between the tests results and the theoretical models in order to confirm the model hypothesis
- detailed design of the possible interventions in order to safeguard the bridge and to adequate the design to the current Standards.
Engineering design (2010-2012) for Federal Ministry of Works (F.M.W.) - Nigeria.
