Combined Loading Relativity Ansysis Of Engineering Structures Under Combined Torsion With Bending Based On Thin-walled Theory

Thin-walled reinforced concrete structures have many advantages suchas good mechanical performance, light weight and low cost, so they havebeen extensively applied in water conservancy, traffic engineering andcivil engineering. But they are usually under combined load cases suchas bend-shear, bend-torsion, bend-shear-torsion, destructions ofthin-walled structures are often caused by the combination of bend, shearand torsion under dynamic loading. Research on torsional structure in ourcountry is a later subject, and at present, the characters of thin-walledstructure members under combined torsion is not fully understood, sofurther research into this field is needed. This paper selected typicalthin-walled structures in traffic engineering and hydraulicengineering—composite bridges and large scale aqueducts, and study onthe combined loading relativity of it under bending moment and torsion,the main points of this paper are as follows:(1) In this paper, corresponding national criterion, current torsiontheories of reinforced concrete and thin-walled structure members weresummarized. Numerial methods of thin-walled structure members wereintroduced. No settled questions exist in thin-walled members undercombined loading, the engineering background and effective value of theselected topics were presented.(2) Based on FEM software (ANSYS) and secondary development tool-ANSYS Parametric Design Language (APDL), corresponding command flowprograms were compiled. Considered interface slip, full-range nonlinearanalysis of thin-walled composite beams with open/box section underbending moment was finished, and the Tecplot post-processing software wasapplied, which uses OpenGL technique, the solution results were revealedintuitionistically and vividly. Results show that box-section compositebeam will greatly increase structures' ultimate bearing capacity. (3) Based on thin-walled theory, using generalized coordinate method,the differential equations for restrained torsion of thin-walled boxsection girder considering the outline deformation was derived. AppliedFORTRAN arithmetic language, corresponding calculate main programs weresuccessfully compiled by using the solver of ordinary differentialequations (ODEs) -COLSYS. The results were input into post-processingsoftware -Tecplot, and output in 2D/3D multicolor status. Based on ANSYSsoftware, selecting included shear deformation 3D beam element, theanalysis of the thin-walled box girder under torsion loading was finished,and the results were compared with corresponding reference. The resultsshow that COLSYS program has the characters of convenience and highprecision.(4) With prescribed generalized coordinate and reasonableassumptions, the differential equation system for restrained torsionanalysis of box-section composite beam was established based on theprinciple of generalized coordinate method, corresponding main programswere compiled using FORTRAN arithmetic language, the solver of ordinarydifferential equations (ODEs)-COLSYS was employed to solve the equationsystem, and the relativity curve and corresponding equations were gainedby comparing the results with the test and theoretical analysis ofcorresponding references.(5) AS a type of thin-walled structures, large scale aqueducts wereselected from Water Transfer Project from South to North of China. Theanalysis of box/U type section thin-walled aqueduct under combinedbending and torsion loading were finished and bending-torsion relativitycurves and equations of the aqueduct were gained through mathematicsanalysis software-Origin7.0. Finally, the two type section aqueductcombined loading relativity was compared.(6) Both relativity compared box-section composite beams withlarge-scale aqueducts under bending-torsion, the results show that:under combined flexure and torsion, the ratio of torsion to bending moment is the main factor for their destruction. When the ratio of torsion tobending moment is small, the bending moment played an important role onthe destruction of structure components, and presents failure withflexural, in contrast, when the torsion has a leading effect on thedestruction of structure components, and presents failure with torsionalfeature, box-section composite beams have obvious effect on bendingmoment increases ultimate torsion and torsion increases ultimate bendingmoment.The interaction equations are gained through the relativity researchon box-section composite beam and large scale aqueduct under bending andtorsion, and results were compared, the results of this paper can providereferences to the design of thin-walled reinforced concrete structuresand the establishment of national specification.