Performance of Quadrilateral Perforated Prestressed Concrete Rafters

Behavior of Perforated Prestressed Concrete Rafters

Abstract

The present study deals with prestressed perforated concrete rafters (PPCRs) system that has been planned and produced to be used for long-spanned roof rafters. PPCRs chose as an alternative preferred option from steel to support roofs. The experimental program consisted of testing seven simply supported prestressed concrete rafters; six rafters are perforated with quadrilateral openings, and the other one is solid as a reference. All rafters were tested under monotonic midpoint load. The variables which have been investigated in this work were number and height of the openings. The results indicate that the presence of quadrilateral openings in PPCR reduces its ultimate load capacity by (4.3 ~ 36) % and increase the mid-span deflection at ultimate load ranging between (14.8 ~ 33) % for PPCRs relative to the non-perforated one (PGB). For rafters having the same configuration extended over the same distance, when the number of openings increased (increasing posts number), the load carrying capacity increases. Whilst its companion deflection decreases for all loading stages. On the other hand, decreasing the depth of the upper and lower chords by 25% for PPCRs having the same openings number coincides with a reduction in ultimate load carrying capacity by (36, 29.5, and 24.5) % for rafters with 6, 8, and 10 openings, respectively, accompanied with a decreasing in mid-span deflection at all loading stages.