İstiklal Street Ziraat Bank — Carbon Fibre Strengthening

Setting up a site on İstiklal Street is a problem in itself. Vehicle access is restricted, pedestrian traffic is heavy and the neighbouring buildings are historic. Under those conditions, strengthening methods needing heavy plant and extensive breaking out are ruled out from the start.

Carbon fibre suits exactly this kind of building: the material can be carried by hand, breaking out is minimal, sections do not grow and the work can be staged. At the Ziraat Bank building the columns were wrapped with fabric and the beams reinforced with plate.

Strengthening within a historic fabric

Working in a setting that has to be protected, method matters as much as the technical decision. The advantages of carbon fibre in that context:

• Sections do not grow — the architectural space and storey height are preserved.
• No heavy plant — the need for cranes and lorries in a narrow street falls away.
• It adds no dead load to the structure — the foundation capacity is not pushed.
• The intervention is reversible — it does not prevent a different approach in the future.

Direction and lap in a column wrap

In a column wrap the fibre direction must run perpendicular to the section; the wrap confines the concrete and increases ductility. Where the lap length is left short, the wrap opens at precisely the moment it is needed. At the corners the concrete is chamfered — a sharp arris cuts the fabric under load.