Prestressed concrete structures are often assumed to be corrosion resistant because of their use of high-strength materials and their crack-free nature. When prestressed concrete structures corrode prematurely, reliable methods of repair and strengthening must be available to minimize the economic consequences. One such method is the use of external prestressing. An investigation into the effectiveness of this method when the internal prestressing steel has suffered various levels of deterioration is described.

University of Wisconsin-Madison’s 5-year winning streak snapped.

At the ACI Fall 2008 Convention, Joint ACI-ASCE Committee 447, Finite Element Analysis of Reinforced Concrete Structures, and ACI Committee 118, Use of Computers, will cosponsor a two-part session titled “Practical Use of Finite Element Analysis in the Design of Concrete Structures.” One of the presentations in the session will cover the modeling of a 25-story hotel building being constructed together with a 60-story residential tower in New York City. The project and its modeling are discussed in this article, including the use of the equivalent slab-beam concept to model the two-way slabs, rigid diaphragms to model slab behavior, and plate elements to model the structural walls.