A quasi-conforming shell element for geometric and material nonlinearity | |
| Author | Lomboy, Gilson Rescober |
| Call Number | AIT Diss. no.ST-07-01 |
| Subject(s) | Finite element method Elastic plates and shelts |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ST-07-01 |
| Abstract | The quasi-conforming technique was introduced in the 1980's to meet the challenge of inter-elements conforming problems and give a unified treatment of both conforming and nonconforming elements. While the linear formulation is well established, fully nonlinear formulations put forward only provided solutions to problems of geometrically nonlinear stiffening. For the case of elasto-plastic material non-linearity, preservation of constructing element matrices explicitly, i.e. without using numerical integration, have led to simplifications that do not account on the spreading of plasticity within the element. The nonlinear formulation based on the quasi-conforming technique that includes geometric and material nonlinearity is presented in this research. The formulation is derived in the framework of an updated Lagrangian stress resultant, co-rotational approach. The geometric nonlinear formulation provides solutions to buckling and post-buckling behaviour while the material nonlinear formulation considers the spread of plasticity within the element while maintaining an explicit construction of element matrices. These are achieved by using constant trial basis functions for the nonlinear strains in the derivation of the geometric stiffness while element elasto-plastic stress field and rigidity matrix functions are defined using interpolation functions to consider the spreading of plasticity. Aside from the elasto-plastic constitutive relation, formulations on laminate composites are also presented, including a method for the analysis of progressive failure of fibre and matrix for quasi-conforming shell elements. Beam, plane and shell elements are derived and subjected to various linear and nonlinear benchmark tests to verify the proposed formulation. An auxiliary objective of this research is the application of derived finite elements to the three-dimensional construction stage analysis of prestressed concrete box girder bridges. Construction stage analysis has been traditionally analyzed with frame elements. The use of frame elements is convenient in modelling and is computationally efficient compared to a full 3D model. However, 3D analysis would include cross-section deformations, more accurate non-prismatic cross-section modelling, localized stresses and strains and transverse prestressing in an integrated manner. The time dependent material functions are based on the ACI and CEB codes. The time dependent concrete material properties considered are changes in strength, elastic modulus, creep and shrinkage. For the prestressing tendon, relaxation effects are considered. Anchorage and friction loses during tendon installations are also included. Two bridge models are analysed using beam and shell elements. |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ST-07-01 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Worsak Kanok-Nukulchai;Kim, Kidu; |
| Examination Committee(s) | Pennung Warnitchai ;Park, Kyung-Ho; |
| Scholarship Donor(s) | AIT Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2007 |