A simplified dynamic condensation scheme with specific application to tall buildings | |
| Author | Alam, Javed |
| Call Number | AIT Thesis no. ST-79-01 |
| Subject(s) | Tall buildings Tall buildings |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | A simple and efficient dynamic condensation scheme for the dynamic analyses of tall multi-storey frames is presented. The floors of the frames are assumed to be rigid in-plane. The masses are assumed to be concentrated at each storey level and only the effect of lateral translational inertia is considered. In the condensation procedure a fraction of lateral nodal displacements are retained as generalized coordinates. The potential energy of the reduced system is written in terms of master nodal displacements, assuming the same transformation relation between master and slave nodal displacements as in the standard static condensation technique. The approximate kinetic energy of the full system is expressed in the velocities of the master coordinates by assuming a linear velocity field between two adjacent masters. Lagrange's equations are employed to derive the equations of motion for the reduced system. The results obtained by the proposed scheme are compared with those obtained using the lumped mass, consistent transformation and various component mode substitution methods. A detailed investigation is made to assess the accuracy and the convergence of the numerical solutions. Numerical examples show that the proposed scheme is superior to the lumped mass method, and comparable to the consistent transformation method. The component mode substitution method predicts accurate results but they are quite sensitive to the choice of normal modes retained. Natural periods for the first few lower modes obtained by the simplified condensation scheme are in good agreement with those of the unreduced system when 30% or more nodal dis placements are retained as generalized coordinates. Finally, dynamic responses for different reduced systems subjected to two types of loading are found to be in good agreement with the corresponding full system responses. |
| Year | 1979 |
| Type | Thesis |
| 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) | Karasudhi, Pisidhi ; Panitan Lukkunaprasit |
| Examination Committee(s) | Worsak Kanok-Nukulchai |
| Scholarship Donor(s) | The United Kingdom Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1979 |