Composite stocky box girders of variable thickness in high-support expressways: Constrained torsional analysis

• Published in: Engineering structures 2021-12, Vol.249, p.113272, Article 113272
• Main Authors: Luo, Yanan, Lu, Xiaoming, Gong, Yaoqing
• Format: Article
• Language: English
• Subjects: Basis functions; Boundary conditions; Boundary value problems; Boundary value problems of ODEs; Box girder bridges; Box girders; Composite stocky box girders; Constrained torsion; Differential equations; Highways; Mathematical models; Nodal line method; Numerical analysis; Ordinary differential equations; Structural analysis; Variable thickness
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2021.113272

•A kind of new theory is formulated for the composite stocky box girders.•The deformation shapes of a CSBG are expressed as a set of the families of curved surfaces.•The mechanics analysis model is a no-simplified CSBG itself.•The mathematical model for the analysis of a CSBG is a set of ODEs.•An ODE based method is developed for the constrained torsional analysis of CSBGs. The constrained torsional problem of composite stocky box girders (CSBG) of variable thickness in high-support expressways is still an intractable challenge in nowadays structural analysis. To surmount this challenge, a kind of new theory for CSBGs is formulated by employing the mindset of mathematical approximation theory in the study. Thusly, the new CSBG’s theory or the real shapes of a CSBG after torsional deformation is expressed as a set of families of curved surfaces by using nodal line method. By the grounds of the new CSBG’s theory and of the energy principle in elasticity, the mathematical model for the constrained torsion problem of a CSBG is transformed into a system of ordinary differential equations (ODEs) containing a finite number of unknown univariate basis functions. This system of ODEs together with their boundary conditions constitute a boundary value problem of ODEs, which can be solved by ODE’s solver. The numerical solutions of the mathematical model of examples reveal some valuable unprecedented occurrences about the behaviours of the CSBG due to pure constrained torsion, and indirectly verify that the CSBG’s theory is reasonable, and that the numerical analysis method illustrated in the study is effective.