Development And Application Of A New Beam-column Joint Element Based On ABAQUS

The beam-column joint of the reinforced concrete frames is the most complicated region of force transferring in the whole structure.In the past few decades,a lot of study of transfer mechanisms of the beam-column joint has been done by scholars home and aboard.And with the development of the theory,some joint element models have been proposed for numerical simulation.So it becomes possible to achieve the more accurate prediction of the full-frame with the influence of the beam-column joints' deformations.Among these models,the super element,which is proposed by Lowes and Mitra,is relatively accurate and efficiently.However,it is a little complex to define the parameters of the shear panel of this model.This restricts its wide application to a certain extent.In this thesis,a new beam-column joint model is proposed on the basis of the super element,in which the shear panel is replaced by an eight-node plane stress element.The new model is relatively easier to define the parameters without the relationship between the shear-stress and the shear-force and is more efficient when being using in the fullframe analysis.The main contents of this thesis are as follows:(1)Firstly,various beam-column joint models are introduced in detail.After comparing these models' advantages,the super model is selected as the prototype of the new element.(2)Secondly,the mechanism of the beam-column joint is studied.And according to its characteristic,the proper material constitutive relationships are selected.Next,it is detailed derived in the theory analysis of the new developed element,and its rigidity matrix is given.(3)Thirdly,Based on the theoritical analysis,the proposed beam-column joint element is implemented in ABAQUS successfully by using the UEL module.Then some key issues about modeling,such as the proper element for the beam and column,the crake of the concrete and the influence of the bond between the concrete and the steel bar,are discussed.(4)Lastly,to thoroughly evaluate the new model,a wide range experimental data from previous investigations of joints,which had different material properties,geometric and design parameters,are collected for verification in this study.Overall,the new joint element is capable of simulating most of the inelastic connection behavior and shows good ability to describe the characteristic of the hysteresis of the joints.However,the simulation results also shows that there exist some exceptions.The analysis and explanation for the exceptions are given followed.