Post-tensioning systems

The containment is a prestressed reinforced concrete structure in the shape of a cylinder with a torispherical dome and a flat foundation mat. The cylindrical portion of the containment is prestressed by a post tensioning system consisting of horizontal tendons and vertical tendons. The dome is prestressed with crossed tendons that are anchored at the dome stiffening ring girder. The foundation mat is conventional reinforced concrete. 

Pre-tensioning and post-tensioning systems using APC materials to rehabilitate concrete structures. 

The causes and effects of corrosion of unbonded single strand tendons are, in several respects, different fixnn those of bonded conventional reinforcing or other post-tensioning systems. Thus, the methods for evaluating and repairing corrosion of single strand tendons are also different in some respects. ... 

Structures built prior to the adoption of these new standards, especially those in aggressive environments, are more likely to experience corrosion of the post-tensioning system than those designed and built since. 

Stains on the surface of the concrete can also provide external evidence of possible internal distress due to corrosion of the post-tensioning system. Grease stains on the soffits of slabs, especially at low points of tendon profiles, can be an indication of unrepaired damage to the tendon sheath as well as shallow concrete cover over the tendons. Such grease staining may be accompanied by water stains or evidence of leaching, indicating water infiltration into the slab tendons. 

Sagiies, A.A., Wang, H. and Powers, R.G. (2005). Corrosion of the Strand -Anchorage System in Post-Tensioned Grouted Assemblies. NACE Corrosion 2005. Paper No. 05266. 

However, it may be feasible to design a system, possibly of interlocked, post-tensioned, prestressed concrete blocks, which would perform tlie structural duties required and maintain adequate biological shielding, but would not require cutting during demolition. As with the PCRV planes of v akness proposals, lack of fit due to tolerances would need to be considered. 

Hassan, T. and Rizkalla, S. (2002), Flexural strengthening of post-tensioned bridge slabs with FRP systems , PCI Journal, Vol. 47, Issue 1, PP- 76-93. 

Structural system, the Coupled Pan Space Frame, a post-tensioned concrete structure developed at the Center for Sustainable Cities. This light, economical space frame is capable of spanning large distances (19 x 19 m or 62.3 x 62.3 ft) with moderate depth (1 m or 3.29 ft) and at the same time allows for systems infrastructure to be interwoven within the depth of the structure. The space frame system also easily accommodates future expansion and modification of the city, allowing the surface to evolve and increase in complexity over time as a response to continued stakeholder scenario-building planning/governance processes. 

Less common are innovative systems, which employ at the connections unbonded or partially bonded post-tensioning tendons alongside non-prestressed longitudinal bars and allow the whole stmcture to rock with respect to the ground, or its components to rock in a stable manner relative to each other as rigid bodies. Sometimes supplemental energy dissipation is added to reduce the displacement response. Such systems were proposed and tested in the end of the last century (Nakaki et al. 1999). They comprise ... 

Lemery s use of mechanical explanations for chemical phenomena is, in fact, very restricted. Although he deploys a particulate matter theory throughout the book, using it both post and ad hoc to explain chemical processes, he actually talks exclusively of only two kinds of shaped particles - acids which are pointy and alkalies which are porous. This system is in marked contrast to that of Descartes who happily postulated shapes for a great variety of particles - smooth, round, straight, bent, branched, hooked, and helical - to explain the properties of everything from oils and salts to magnetic attraction.11 Moreover, Lemery s explanations based on the shapes of acid and alkali particles alone creates a serious, but hitherto unremarked, tension within his chymical system. For Lemery equally maintains the traditional... 

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