| The sectional analysis method is a fundamental method embedded in the designcode of reinforced concrete structures, and most of the element models are also basedon it. For specimen with large shear span ratio, the sectional analysis method withoutshear can simulate its behavior well. However, most of softwares do not adequatelycapture shear-relate influence of shear-critical RC specimen.The purpose of this study is to develope and verify a nonliear sectional-analysismodel and a beam-column element model with the aim of capturing shear-relatedmechanisms accurately、resonablely as well as numerical stability under general loadingconditions.The thesis consists of three major parts:①Develop a nonlinear sectional-analysis model with shear，which is based on theModified Compression Field Theory（MCFT）；The modified dural-section methoddevelopd in the thesis is used to determine the shear strain/transverse normal stressdistribution along the section depth； and crack-closing effect is taken into account inthe concrete hysteresis constituitive model.②With the combination of section model with shear and the Timoshenkobeam-column element, a2D beam-column element model with shear is developed，Themodel is developed based on Hu-Washizu variational principle, which not only cansolve the problem of shear locking but also has good numerical stability and robustness.③To overcome the numerical problem of current iterative method based ontangent stiffness， a displacement-control method based on secant stiffness with originpoint of definition secant-stiff shift developed.Analyses of several shear-critical specimen demonstrate that the developed modelis highly successful in simulating the experimental responses in terms of load-deflectionresponse, failure mode, failure displacement, total energy dissipation, displacementductility ratio. |
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