NUMERICAL INVESTIGATION ON PERFORMANCE OF STEEL CONCRETE COMPOSITE BEAMS UNDER COMBINED NEGATIVE AND TORSIONAL LOADING STRENGTHENING BY COVER PLATE AND STEEL FIBRES

Abstract

To support all loads exerted during the service life, steel-concrete composite beams combine the benefits of both steel and concrete components. Due to the need of service of the structure, torsion moment were induced which causes a significant loss in load carrying capacity and introduces a change of mode of failure on the composite beams. In addition, in different ratio between the applied negative bending and torsional moments of a composite beam increases more, deflection and its consequent problems become a matter of concern. The major goal of this research is to use steel plate cover and steel fiber to increase the stiffness and load carrying capability of composite beams subjected to combined negative bending and torsional loading. Numerical analysis was done via ABAQUS software to examine the non-linear stress-strain behavior of steel-concrete composite beams. Straight steel concrete composite beams are modeled examined under Combined Negative and Torsional Loading. To get load carrying capacity steel plate cover and steel fiber are used in steel beam and concrete slab respectively. Addition of steel plate cover with length (1900mm and 2400mm) at bottom flange of steel beam gave better result and also steel fiber reinforced concrete are considered to investigate the effect of combined load. As inferred from the FEA output results the addition of steel plate cover boost the performance of load carrying capacity. Due to steel cover plate at bottom flange it is increased to 8.89 % for load applying (stage-1 and satage-2) and 15.06 % for load applying (stage-2) only which gave in different ratio of torsion to negative bending moment. As a length of steel cover increased the load carrying capacity boosted at the percentage of 6.81% and 8.89 % for specimen-1, and 5.2% and 15.06% for specimen-2. Likewise, 1.6 % and 2.7%, improvement of load carrying capacity are observed by adding steel fiber on normal concrete which have good effect on crack initiation and propagation.