Nonlinear Finite-element Analysis On Flexural Behavior Of Pre-stressed Steel I-beam With External Tendons

Prestressing with external tendon is one of the efficient techniques for thestrengthening of steel structures as well as controlling the overall deflection. Thistechnique can use for the new structure as well as for rehabilitation of existing structures.A three-dimensional nonlinear finite-element analysis had been performed duringthis study to investigate the prestressing effects on flexure behavior and the structureresponse of prestressed simply supported steel I-beam prestressed with externallyunbonded tendon. ANSYS software had been used to analyze and simulate the process ofapplying prestressing force to FEM. A plasticity model with Alternative bilinear isotropicbehavior had been used to define the mechanical properties of the steel material. TheFEM controlled by Newton s method as convergence criteria. The initial imperfectionsand the buckling modes of the unloaded beam were taken into consideration as an initialcondition to indicate its effect on the structural behavior. The initial imperfectionconsidered to be1/1000of the beam span. The effect of bracing“lateral restraintconditions”had been considered at the top flange and the bottom flange of the steel beamafter applying the prestressing force on the tendon taking into account the situationduring the tensioning and the coordinate positioning of the model.This thesis consisting of two main parts, the first one is verification study onexisting experimental results. The results obtained that the finite-element model conductby ANSYS can simulate the behavior of prestressed steel beam and shown goodagreement with the existing experimental results. Whereas, the second part is aparametric study on simply supported steel beams with span length of30meters. Theeffect of several factors on the overall behavior of prestressed beams had been conductedin this part in terms of the number of deviator, eccentricity of the external tendon, prestressing technique, tendon profile, and type of loading. In each numerical analysis,one factor considered to vary while other factors held constants to isolate the effects ofthe considered parameter.