Hammersmith Flyover Phase II Strengthening, Warrington

26 May, 2016 | 18:30 - 20:30

The new strengthening cables being pulled through.
The new strengthening cables being pulled through.

About this event

Hammersmith Flyover is an early precast segmental bridge with prestress which is described as "external" but runs in grouted ducts for part of its length.

The prestress was found to be deteriorating seriously and emergency strengthening to critical sections was installed in early 2012. It was decided in anticipation of further deterioration that new prestress should be installed to make the structure independent of the original prestress and allow for the possibility of this eventually becoming completely ineffective. It is believed to be the first time full replacement prestress has been installed in a bridge where it was not possible to remove the original.

The design, design approach and challenges will be described. This includes use of innovative ultra-high performance fibre reinforced concrete prestres anchors (some precast, some cast in situ using a novel syringe) which have already won an award for Freyssinet and bespoke design approaches based on EN 1992.

Much of the difficulty resulted from the form of the bridge which left very little space for the new prestress and from the requirement to keep the bridge open and minimise disruption to traffic below as well as on the bridge.

The bearings, which are unusually located at the bottom of the piers in pits, are also being replaced and this aspect of the Project will be more briefly considered. The value of and issues with the "Early Contractor Involvement" approach used will also be considered. The work is being undertaken by an integrated team of owner, TfL, Contractor, Costain and Designer, Ramboll Parson Brinckerhoff.

Speaker: Dr Paul Jackson

Refreshments will be served from 18:00 for a meeting start of 18:30.

Organised by Cheshire Branch in conjunction with IStructE.

Scan of the bridge
Scan of the bridge
Insalling the new anchor points
Insalling the new anchor points
Strengthening cables in place
Strengthening cables in place

Speaker

Dr Paul Jackson

Dr Paul Jackson is a Technical Director of Ramboll UK. He has approaching 40 years experience of design, construction and research much of it related to concrete bridges. He joined Ramboll (then Gifford) from BCA in 1988 and has served on code committees continuously since the early 1980s. He is the immediate past chairman of the Southern Regional Group of the Institution of Structural Engineers.

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