Abstract
Investigation was conducted at the Civil Engineering laboratory of the Texas A & M University to observe the flexural behavior of prestressed composite T-beams of lightweight aggregate concrete. Tests were made on twelve beams comprising two series. The first series consisted of five beams without shear connectors but stirrups were used in the precast web to prevent premature shear failure. In the second series, the stirrups were extended into the flange for use as shear connectors. The variables in the tests were (a) strength of in-situ flange, (b) length of shear span, and (c) time interval between castings. The composite T-beams were constant in cross section and length. A rectangular web 3 in. x 9 in. was used to combine with an in-situ flange 12 in. wide and 2.5 in. thick. The beams were 10 ft. in length, with an effective span of 9 ft. Nominal concrete strength of 4000 psi at 7 days was used for the prestressed precast web and nominal concrete strengths of 2000 psi, 3000 psi, and 5000 psi at 7 days were used for the in-situ flange. Except for two flanges which were cast on the fourteenth and twenty-eighth day after the casting of the webs, all the flanges were cast on the twenty-first day. Two 0.375 in. diameter high tensile steel strands, each stressed to a prestressing force of 14,000 lb, were used in each beam. Mild steel deformed bars with a diameter of 0. 375 in. were used as stirrups and shear connectors. Creep and shrinkage strains in beams and control specimens were periodically observed up to the time of testing for computing loss in prestressing force and differential shrinkage between precast web and cast-in-situ flange. The beams were tested between 14 to 16 days after casting of the flanges. ...
Hasnat, Abul (1965). Behavior of prestressed composite T-beams of lightweight aggregate concrete. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -174790.