A softened membrane model for prestressed concrete composite box girders with corrugated steel webs under pure torsion

Abstract

Torsion can be regarded as a principal factor in some cases, such as in curved girders and eccentrically loaded girders, when conducting the structural analysis of prestressed concrete composite box girders with corrugated steel webs. Recently, a rational model, called the softened membrane model for torsion, was proposed for the torsional analysis of reinforced concrete members; thereafter, this model was extended to prestressed concrete members under pure torsion and called softened membrane model for torsion prestressed concrete. This article presents a modified model, the softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs, to analyze full torsional behavior. To build the model, the softened membrane model for torsion in reinforced concrete members is first extended to perform the torsional analysis of prestressed concrete composite box girders with corrugated steel webs by incorporating the torsional contribution of corrugated steel webs. Afterward, the initial stresses and strains due to prestressing are considered to extend the softened membrane model for torsion to softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs by modifying the equilibrium equations, convergence criteria, and constitutive laws of materials. The modified model is validated by experimental data and is proven to be capable of predicting the overall torque–twist curve, especially the precracked branch and postcracked ascending branch. In addition, a comparison between the softened membrane model for torsion and softened membrane model for torsion prestressed concrete indicates that the torque values before and after concrete cracking will be overestimated and underestimated, respectively, without considering the effect of the initial stresses and strains. Finally, another comparison shows that the softened membrane model for torsion prestressed concrete is superior to the rotating-angle truss model for torsion in its ability to predict the precracked branch of the torque–twist curve.

Modified rotating-angle softened truss model for composite box-girder with corrugated steel webs under pure torsion

“…Due to the integrity of whole cross section, it is inaccurate that the torsional deformation coordination of CBGCSW is only in terms with that of TBSC in previous research (Ko et al, 2013;Mo et al, 2000;Shen et al, 2018aShen et al, , 2018bShen et al, , 2018d. In other words, the twist of CBGCSW is not only related to shear strain and geometry of TBSC, but also related to that of CSW (Nie and Tang, 2007).…”

“…Based on FA theory, Ding et al (2013b) first proposed a theoretical model to calculate the performance of CBGCSW under pure torsion, which was verified by test results in available literature, and Ding et al (2013a) also conducted a test on four scaled specimens to analyze the impact of influencing factors on ultimate torque of CBGCSW, such as thickness of CSW, concrete strength, and type of corrugation shape. Afterwards, considering biaxial constitutive laws of concrete and Poisson effect in post-cracking stage, Shen et al (2018aShen et al ( , 2018b extended softened membrane model (a type of FA theory) for concrete members to single-box multi-cell CBGCSW under torsion, and comparisons of the proposed model with test data showed that the proposed softened membrane model was capable of computing torsional performance of CBGCSW with multi-cell. Besides, Zhou et al (2019) proposed a two-stage shear strain relationship between TBSC and CSW for softened membrane model to calculate the torsional nonlinear performance.…”

Fatigue Performance of Steel‐Concrete Composite Continuous Box Girder Bridge Deck

“…Compared with concrete bridges, steel-concrete composite structure bridges have the advantages of a lower self-weight and a larger span; compared with steel bridges, they have the advantages of less steel consumption, better structural stability, higher bending rigidity, and higher ductility [1][2][3]. However, steel-concrete composite beams are prone to fatigue problems under long-term repeated loading [2,[4][5][6].…”