الفهرس | Only 14 pages are availabe for public view |
Abstract Prestressed concrete is widely used in the construction industry in buildings, bridges, towers, pressure vessels and offshore structures. In numerous structures, the architectural requirements prescribe the incorporation of long span and slender elements in which the prestressed concrete is rendered the most feasible design alternative. The strength and serviceability of reinforced concrete (RC) and prestressed concrete (PC) elements are generally affected after fire exposure. The basic design objective for such elements would be life safety and collapse prevention. The main objective of this investigation is to the study behavior of statically determinate prestressed concrete beams subjected to fire. In this respect, an extensive experimental! analytical investigation was conduced on number of medium scale post-tensioned concrete girders subjected to fire. The experimental program consisted of testing twelve beams, fIve of which were partially prestressed, five beams fully prestressed and the remaining two beams are non prestressed beams. The beams had an overall width, depth and length of 160, 340 and 4400 mrn, respectively. The beams were simply supported with a clear span of 4000 mm. The prestressing strand had a harped profile similar to the shape of the applied bending moment. The main test variables are concrete compressive strength, concrete cover and prestressing index. All prestressing specimens were cast using bonded prestressing strands. The strands were stressed after the concrete had reached an age of 28 days, and then grouted with cementitous grout. The test program was divided into two phases. Five beams were tested as control beams and the remaining seven beams were loaded and exposed to fire at level of 600°C for a three hours duration. |