Where, s 1 and s 2 were the top and bottom fiber stresses, P i was the initial restressing force; A was the cross sectional area; e was the eccentricity of centroid of prestressing steel
with respect to centroid of the gross section; I x was the moment of inertia; C t and C b were the distance from the entroid of gross section to top and bottom fibers, respectively.
How it works is that post-tensioning tendons - which are prestressing steel
cables inside plastic ducts or sleeves - are positioned in the forms before the concrete is placed.
Joining the officers on the PTI Executive Committee are Post-Tensioning Company Representative Todd Stevens of Gerdau-SFS Post-Tension Division; Professional Member Representative Cary Kopczynski; Associate Representative Paul Hohensee of Precision Hayes International; and, Prestressing Steel
Manufacturer Representative Joseph Napoli of Insteel Wire Products.
To characterize the prestressing steel
in tension, as discussed by Wang (2006), a tensile [sigma]-[epsilon] relationship for bare prestressing strands can be used since that the decreased stress in embedded tendons compared with bare strands is less significant than in embedded mild steel compared with bare steel bars.
Concerning SCC phenomena it has to be underlined that in prestressing steel
they evolve through complex and different mechanisms, where anodic metal dissolution and hydrogen embrittlement (HE) are not unique stages [11-12].
On 4 April, the European Commission reduced by 80% the fine levied against steel giant ArcelorMittal for participating in a cartel operated by prestressing steel
The stress-laminated technique consists of a series of timber planks placed side by side between supports of the bridge and compressed transversely with high-strength prestressing steel
THE EUROPEAN Commission has fined 17 producers of prestressing steel
Euro 518 million for operating a cartel that lasted 18 years until 2002 and covered all but three of the then 15 European Union (EU) member states--Britain, Ireland and Greece.
The concrete provides perfect protection for the steel, passivating any corrosive reactions, and the prestressing steel
keeps the concrete in the tank walls under constant compression to enhance its water-tightness.
The stress in the prestressing steel
varies continually with time due to the effect of concrete shrinkage and creep, and the steel relaxation.
In addition, projects are underway to develop new technologies for the evaluation of prestressing steel
in pre-stressed concrete, the evaluation of bridge substructures, and the development of special tools and methods to evaluate stay cables.
With regard to the prestressed concrete bridges, this refers especially to the embedded reinforcing and prestressing steel
in cracked sections.