A more rational scheme to well-pose seismic soil-structure interaction problems | |
| Author | Sakda Katawaethwarag |
| Call Number | AIT Diss. no.ST-11-01 |
| Subject(s) | Seismic Soil structure |
| 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-11-01 |
| Abstract | The method proposed presently replaces th e propagating rupture on the fault surface by a fictitious focal point and a seismogra ph station in the vicinity of the given soil site. The scheme is used to calibrate the free field ground motion of the soil site. The harmonic vibration analysis of the half space, in which elastodynamic infinite elements are adopted in the far field and finite elements in the near field , yields the Fourier transform of any constituent wave in terms of the amplitude of the forces applied at the focal point, thus in terms of the Fourier transforms of th e accelerations in three orthogonal directions recorded at a seismograph station. Rationally used are far-field Green's functions as the shape functions of infinite element nodal lines. The ma ss and stiffness matrices of infinite elements involve exponential integral , for which the Gauss-Laguerre integration is used. If a seismograph station is in the far field (as it is usually), the recorded values there can be transformed into the values at the infinite element node by means of appropriate shape functions. The results can be more refined in case of the availability of simultaneous records at more seismograph stations. For example in case of N stations, we assume N fictitious focal points in the same vertical line, and solve a set of 3N simultaneous equations of 3N forces, three orthogonal forces at each focal point. Naturally, the results by the present method are ‘exact’ at the calibrated points, and should be accurate in- between and near those points. The accelerations at the points near seismograph stations at various depths can also be obtained. An appropriate inverse Fourier transform algorithm properly yields all results as time functions. The proposed method is also used to so lve the problems of seismic response of structures in the soil domain, such as foundations of st ructures and nuclear containment structures. The seismic analysis of the finite embedded body, in which elastodynamic infinite elements are adopted in the far field and finite elements in the near field , uses the difference scheme to solve the problem. The impedance equations, governing the difference between the embedded body and the seismic free field , contain the difference displacements and the already known free-field quantities. No infinite element free-field node is involved in the analysis of the difference system. The results of a cylindrical foundation of the structure em bedded in a layered half space subjected to earthquake excitations in three orthogonal directions simultaneously are obtained. The proposed method could be extended to the seismic analys is of more complicated structures and the analysis / calibration of underground detonations |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ST-11-01 |
| 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) | Pisidhi Karasudhi ;Pennung Warnitchai (Co-Chairperson); |
| Examination Committee(s) | Worsak Kanok-Nukulchai ;Bergado, Dennes T.; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2011 |