Effects of Banded Post-Tensioning in a Prestressed Concrete Flat Slab

摘要

A new class of flat slab concrete bridges employs bidirectional post-tensioning.While longitudinal post-tensioning is uniform, transverse tendons are concentrated in the vicinity of column lines to act as bentcap-like supports. For multispan structures, transverse post-tensioning is limited to a series of narrow banded regions. The report, first in a series, documents displacement, strain, stress, and punch-through shear capacity of a 3/10ths scale model of a column and slab region of a prototype bridge. Concomitant efforts are underway on a large two-span laboratory bridge model, a field study of a full-size bridge, and a numerical simulation package. The current study investigates degree of validity of a design procedure for a column region of a prototype bridge. Construction, instrumentation, testing, and numerical simulation are described for the concrete model slab. A loading schedule enables stress distribution determination for a variety of tendon and load patterns. The number of stressed tendons varies from one to nine. Results of a large number of transducer readings and finite element simulations are presented via fringe plots, tables, and graphs. Finally, the slab is loaded by a specially fabricated load frame and the circular support column so as to impose punch-through shear failure.