Ing. Pierangelo Pistoletti speaks about two passions that he harbors: one is for bridges, and the other is for stainless steel. He is fascinated about bridges because of their challenging structural complexity and about stainless steel because of the superior solutions that the material presents to the structural challenges.

Ing. Pistoletti explains why stainless steel, rather than mild steel, is an ideal material for load-bearing structures in bridges, “Mild steel poses a risk for critical structures, because without regular coating the structures can be attacked by serious corrosion, leading to material fatigue and even to a risk of collapse. Regular coating to fight corrosion is also costly.” He is an ardent spokesman for stainless steel to municipal decision-makers, as their mandate is to ensure public safety on a long-term and wise infrastructure investments.

Ing. Pierangelo Pistoletti is a leading expert in bridge design and steel engineering.

The City of Siena in Tuscany, Italy had trusted Ing. Pistoletti with several bridge designs before when they turned to him again to design a footbridge over a busy motorway in the suburb of Ruffolo. Ing. Pistoletti and his engineering firm SETECO went to work on an all-stainless steel, cable-stayed bridge. The process took a new turn when Outokumpu’s Italian marketing arm Outokumpu S.p.A. introduced SETECO to a new material: LDX 2101® duplex stainless steel developed by Outokumpu and produced by no other stainless steel maker.

LDX 2101® is a lean duplex grade that provides the excellent properties of duplex stainless steels – good pitting and crevice corrosion resistance and high tensile and yield strength – but has a nickel content of only 1.5%. As a result, LDX 2101® has less price volatility than high-nickel stainless steels. The grade is ideal for load-bearing structures where moderate corrosion resistance is adequate such as in Siena, an inland city with low pollution levels.

Ing. Pistoletti was persuaded by the merits of the material and specified LDX 2101® for the towers and roadway of the bridge. Siena city representatives were no less impressed, attracted to the long, maintenance-free life and unfading good looks that the material promised. The high strength of LDX 2101® enabled Ing. Pistoletti to design a light-weight structure compared to traditional bridge designs.

Outokumpu brought more value into project with its “lego” service concept, successfully used in a large number of bridge construction projects worldwide: plates are hot rolled and ground for the purpose, they are cut and bent into customized bridge components, and the edges are prepared for welding. The components are easily joined at the site.

The plates for the Siena footbridge were produced at Outokumpu’s Hot Rolled Plate plant in Degerfors, Sweden and plasma-cut at the Outokumpu plate service center in Solbiate Olona, Italy. Outokumpu provided technical assistance for the builders. The “lego” assembly helped minimize the impact of the construction on the surroundings.

The Siena footbridge sets a precedent in infrastructure development. Using LDX 2101®, investment costs involving stainless steel become increasingly affordable, so this duplex grade from Outokumpu opens up a wealth of opportunities to use stainless steel wherever high strength and corrosion resistance are essential.

Siena footbridge facts:
Owner: City of Siena, Italy
Location: Ruffolo, Siena
Completion: Summer 2006
Architect: Ing. Pierangelo Pistoletti, SETECO
Structural engineering: SETECO
Contractor: MMI
Type: cable-stayed footbridge
Span: 60 m
Material: LDX 2101® duplex stainless steel plates from Outokumpu, processed at Outokumpu’s plate service center in Italy
Surface finish: 1D

For more information, contact:

Marco Frigo
Business Development
Outokumpu S.p.A., Genova, Italy
Tel. +39 010 554 3237
E-mail: marco.frigo@outokumpu.com

Anders Finnås
Product and Business Development
Outokumpu Hot Rolled Plate, Degerfors, Sweden
Tel. +46 586 47 131
E-mail: anders.finnas@outokumpu.com

The Siena footbridge under construction in 2006.