Finite element analysis and parametric study of continuous steel–concrete composite beams stiffened with post-tensioned tendons

Abstract

Externally post-tensioned tendons can cause an initial compressive stress in steel-concrete composite sections at the hogging moment region, and then a part of the tensile stress in the concrete flange can be relieved. This study presents a detailed finite element analysis of the nonlinear flexural response of continuous steel-concrete composite beams strengthened with externally post-tensioned tendons. The initial post-tensioning force is introduced as an initial strain in the truss element that used to simulate the external tendons. The accuracy of the finite element model is validated using existing experimental works. The effects of tendon eccentricity, longitudinal steel rebar ratio, and initial post-tensioning force on the beam behavior are explored. Furthermore, deterministic and stochastic shrinkage effects are carried out to obtain the long-term random responses of the strengthened beams as well as unstrengthened beams. However, the ultimate capacity of the strengthened beam increases only by 8%, the cracked moment redoubles, and an affirmative behavior over the unstrengthened beams is obtained. Also, a rapid decay in the long-term deformation of continuous steelconcrete composite beams is obtained at the early age while a linear decrease in the remaining part of the age occurs.

Numerical Modeling and Analysis of Strengthened Steel–Concrete Composite Beams in Sagging and Hogging Moment Regions

“…No initial tensile strains are created due to the secondary moments, caused by the effect of the eccentricity of the external post-tensioning, because the small eccentricity and the initial axial compressive strains overcome these tensile strains. Table 8 presents a summary of FE results to highlight the effect of the external post-tensioning at the hogging moment regions [17]. The composite beam exhibited an initial downward deflection of 1.2 mm due to the effect of the external post-tensioning.…”

“…Numerical research was carried out on the behavior of continuous prestressed composite beams at hogging moment regions. The beam capacity increased only by 8%, and the cracked moment redoubled [17]. The vertical shear strength of continuous composite beams is significantly influenced by the concrete slab, and it rises as the degree of shear connection is increased [18].…”

“…Reliable FE models were developed for the accurate modeling of composite beams under negative and positive moments [10][11][12][13][14][15][16][17][18][19]. Special focus was placed on the shear connectors connecting the concrete slab and steel I-beam.…”

Some Aspects of Numerical Modeling of Steel-Concrete Composite Beams with Prestressed Tendons

“…Acceptable matching between experimental and analytical results is then found, however no FE study was realized. In El-zohairy et al (2017), a numerical and parametric FE study is realized in composite beams with internal and external tendons for ultimate loads. Validation with experimental results is provided for external posttensioned composite beams only, but analyses including unbonded and bonded internal tendons are not compared with experimental dataset.…”

Beam-tendon finite elements for post-tensioned steel-concrete composite beams with partial interaction

“…The studied parameters include different cases of loading, tendon profiles, beam spans, initial prestressing levels and different dimensions of steel sections and concrete deck, for different tendon layouts. Other works on PSCCB's based on nonlinear static 3D analysis were recently published [16,17].…”