METHODOLOGY FOR MONITORING THE FLEXURAL BEHAV-IOR OF STRUCTURAL CONCRETE MEMBERS WITH UNBONDED INTERNAL STEEL

This paper presents a numerical methodology for a nonlinear analysis model to investigate the complete load vector versus strain vector and the deformational response of structural concrete members reinforced with unbonded post-tensioned steel and conventional nonprestressed steel. The adopted calculation procedure of this methodology includes an iterative algorithm for determining the strain and the stress in concrete, unbonded prestressed steel and nonprestressed steel at different loading steps including the ultimate stage. Based on the nonlinear analysis that performed at different sections along the beam and depending on the attained stress-strain state of the structural concrete member under the applied loading, the stress in unbonded steel is determined using an extensive iterative procedure. During any loading step, the analysis is repeated until the strains in concrete, unbonded prestressed steel, and nonprestressed steel are evaluated within a reasonable tolerance, an experimental verification was carried out using test results taken from four different investigations that performed between 1976 and 1991 on different flexural concrete members. It was observed that an excellent correlation was found between the results of the proposed methodology and the experimental tests.