Experimental and Theoretical Study of the Composite Rolled and Corresponding Castellated Steel Beams Under Torsion

Abstract

1-1 Overview

One of the most common applications of composite action between two materials occurring in structural engineering is that between steel beams and an overlaying concrete slab. To insure composite action, shear connectors are welded to the top flange of the steel beam and embedded in the concrete slab. The necessary connection between the slab and the beam is provided either by the bond between concrete and steel for full encasement or by mechanical shear connectors. Adequate bond is necessary to transfer longitudinal shear from the slab to the beam so that the two will act as one unit. In addition to longitudinal shear transfer, bond devices must insure that steel and concrete can not separate vertically. Whenever there are no shear connectors and the surfaces between steel beam and concrete slab are smooth, slip occurs so that the beam and slab act separately. Castellated beams are not widely used in Egypt in spite of the many advantages of this type of beams. These advantages are (i) giving opportunity to have many cross-sections in standard tables of Egyptian steel and (ii) allowing electro-mechanical equipment such as electric cables and water pipes to pass through. Many investigations have been carried out in the field for rigid and relatively light structures, such as steel beams, plate girders, composite steel beams and composite castellated steel beams. Advanced investigations of structural engineering require that the structures have to be are represented and investigated experimentally and that the analysis of the experimental results to be compared one the theoretical analyses are established. This is the most modem and the best when the investigated structures are of the heavy element type, such as composite structure [28].

1-2 Objectives

The objectives of this investigation are: (i) derivation of the torsional properties for the composite castellated beams; (ii) performing nonlinear analysis of composite rolled and castellated beams using the finite element approach; (iii) studying experimentally the structural behavior of composite rolled and castellated steel beams under torsion. Experimental program includes six tests of composite steel beams are