Sales & Technical: +44 (0)20 8735 5200 | ROI: +353 (01) 695 0726 | [email protected]

Strengthened bridge meets EU load standards

Client:	Sheffield City Council
Location:	Low Bradfield, Sheffield
Approved Installer:	Goldhawk Restorations
Reference No:	CS145

Built around 1850, the Smithy Bridge is a stone construction, with a single span of 6.7m, crossing Agden Dyke which flows from the Agden Reservoir.

Following a structural assessment, the bridge was restricted to a gross vehicle weight of 10 tonnes and so did not meet the current required load bearing standards for highway bridges.

Helifix was contacted by Amey engineers to undertake a survey of the bridge and establish whether it could be strengthened sufficiently to increase its capacity to 40-44 tonnes in order to meet current standards. As it is in the Low Bradfield conservation area, which lies within the Peak District National Park, it was also important that any repairs preserved the bridge's aesthetics.

The Helifix solution

Goldhawk carried out a full structural assessment of the bridge using the ASSARC computer software program, enabling an optimised repair and strengthening scheme to be devised by the MARSYS computer package.

The bridge strengthening grid pattern was marked out on the underside of the arch and narrow longitudinal and radial slots cut into the masonry.

Stainless steel HeliBars were bonded into the slots using Marflex and interlocking hooked CemTies installed with HeliBond grout, at right angles to the HeliBars, up into the arch ring at the grid intersections. Normal structural movement was accommodated with minimal disturbance to the retained original masonry.

The entire concealed reinforcement was encapsulated with Marflex, an elastic structural adhesive comprising durable polyureide resin with high bond strength, which can be colour matched to leave the bridge virtually unchanged.

The weak Smithy Bridge was sympathetically and economically strengthened to accept full highway loadings and comply with EU regulation. The concealed repairs left the bridge virtually unchanged but with its structural integrity restored at a fraction of the cost of full bridge replacement.