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Structural Strengthening, QatarSIKA AT WORK Structural Strengthening, Qatar
PROJECT DESCRIPTIONThe Ummgarn Interchange Bridges N29 are located near Simaishma. The North and South Bridges are constructed identically; the deck comprises of a single cell two-span continuous post-tensioned box girder with cast-in-situ concrete, with each span being 35m.
PROJECT REQUIREMENTSThe Ummgarn Interchange twin-bridges N29 were damaged by strikes from a transporter vehicle passing underneath. Both the North and South Bridges were struck in their soffits causing severe damage and the North Bridge was found to bear severe damage in its soffit, post-tensioned strand and support bearings. Eight tendons are located in each web and one tendon was partially damaged due to the impact of the transporter vehicle. The damage of the existing tendon causes a lack of longitudinal flexural strength. The South Bridge sustained lesser damage with some loss to the concrete section.
SIKA SOLUTION The damaged concrete was removed and recasted with Sikacrete®113PP. The longitudinal flexure strength of the box girder was restored with 16 Sika® CarboStress®. The tensioned plates were installed on the inside of the box girder, acting as an external post tensioning. The tensioning force is transferred to the concrete only at the ends of the plates and these were carefully located to achieve the maximum strengthening effect. In order to ensure the connection between the box girder slab and the web, eight layers of SikaWrap-301C were installed at the outside of the box girder.
This is the first time this system has been used in the Middle East.
WHO WE ARESika AG, Switzerland, is a globally active specialty chemicals company. Sika supplies the building and construction industry as well as manufacturing industries (automotive, bus, truck, rail, solar and wind power plants, façades). Sika is a leader in processing materials used in sealing, bonding, damping, reinforcing and protecting load bearing structures. Sika’s product lines feature high quality concrete admixtures, specialty mortars, sealants and adhesives, damping and reinforcing materials, structural strengthening systems, industrial flooring as well as roofing and waterproofing systems.
Sika® CarboStress® tendons are supplied ready to installTensioning the Sika® CarboStress® tendon using hydraulic jack