FLEXURAL BEHAVIOR OF VOIDED SLABS PRETENSIONED WITH REINFORCING BARS

Faculty of Engineering, Zagazig University

This paper introduces the construction, instrumentation and the experimental work of prestressed voided slab

models pretensioned with deformed reinforcing bars of grade 360/520. The objective is to examine their flexural

behavior at service and at collapse, as well as the potential of using reinforcing steel instead of prestressing steel

in the pretensioning of such systems. Three pretensioned voided slabs of 1500 mm length, 650 mm width, and

70 mm thickness were built and tested under monotonically increasing uniformly distributed load. The process

of pre-tensioning and anchoring is presented including the design and building of a prestressing steel frame. The

specimens were constructed with low-shrinkage concrete in order to reduce the prestress losses due to shrinkage.

A reinforced concrete reference specimen with the same dimensions was built and tested for comparison

purposes. Experimental work was conducted on the specimens to evaluate their flexure behavior (load-deflection

relation) and their ultimate capacity. Their structural adequacy was evaluated and the gain of prestressing found

to reduce cracking and significantly increases their flexural resistance (about 38 %). However, this occurs in

exchange with little reduction in their flexural ductility, about 25 %.