Behaviour of post-tensioned prestressed concrete T-beams with large web openings

摘要

The results of analytical and experimental investigation on the behaviour of simply supported prestressed concrete T-beams with web openings are presented in this paper.Thestudyconsistedoftesting9T-beamsofsize36cm×5cmflangeand30cm×8cm weband of span4.2m gradually loaded tofailure. Each beam had webopeningsof size 36 cm × 12 cm. The variables considered were the size of openings, location of openings and type of reinforcement around openings. The openings were positioned both in the shear span as well as in flexure span. Measured ultimate loads and moments are compared with those calculated from the theoretical values computed from the codes of practice as well as those based on Vierendeel truss analogy. The ratio of the observed to calculated ultimate load indicated that there exists shear concentration at the openings. The deflections were well within those allowed by the code provisions. The results show that large web openings can be accommodated in post-tensioned prestressed concrete T-beams without sacrificing the strength. Serviceability requirements are also found to be satisfactory. The beams which were reloaded after failure carried 60 to 70 percent of their ultimate load thus exhibiting the resilient characteristics of prestressed concrete in spite of the discontinuities.