Abstrakt

This project refers to the study the shear zone, under full and partial prestressing in comparison to beams with passive reinforcement.For comparison, variable parameters have been determined:- a/d (from 1,5 to 3,5) - it's shear span to effective depth of the beam . Assuming constant geometrical quantities, "a" is variable.- 26 beams had no vertical shear reinforcement, and the other 26 had closed stirrups.- prestressing intensity was given by "λ", the ratio of active reinforcement in the form of prestressed steel strands and passive reinforcement (ribbed steel bars). To retain constant beam load capacity on bending with changing prestressing intensity, single prestressing strands replaced adequate to the ripping force of ribbed bars.- prestressed strands' adhesion to the concrete - 18 beams were prestressed with unbonded and 18 with bonded strands.All tested beams had the same T-shaped section and their geometrical dimensions were: length 290cm, height 320 mm, width of flange 200mm and web 100 mm, effective depth of beam 220mm, height of flange 70mm. The beams were placed on the supports with l=210cm spacing.

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