Comparative study of the seismic response of the Pantabangan Main Dam using simplified and finite element methods | |
| Author | Carreon, Ronaldo L. |
| Call Number | AIT Thesis no. GE-95-08 |
| Subject(s) | Earthquake hazard analysis--Philippines--Pantabangan Dam Finite element method |
| Note | A thesis submitted in partials fulfilment of the requirements for the degree of Master of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-95-08 |
| Abstract | On July 16, 1990, a magnitude 7.8 (M.) earthquake struck the island of Luzon, in no1thern Philippines, originating from the left-lateral strike-slip motion which occurred along the Philippine Fault. The Pantabangan Main Dam, located approximately 10 km from the nearest ground rupture, was one of the major earth structures affected by the earthquake. At the maximum section of the dam, a crest settlement of 26 centimeters was observed with the settlements decreasing uniformly towards each abutment. Transverse tension cracks and other minor damage was observed but the dam was found to be in generally good condition after the earthquake with no sign of slope instability. The performance of the dam during this earthquake was evaluated in this study, focusing mainly on the analysis of permanent defonnations. The simplified method of estimating earthquakeinduced permanent deformations of dams and embankments proposed by MAKDISI and SEED (1977), originally developed for dams in the height range of 30 to 60 meters, was employed in the analysis. Due to the lack of available strong-motion records of the earthquake, the analysis of the dam was made using 3 input motions from the 1992 Landers earthquake and the 1989 Loma Prieta earthquake in California, both earthquakes caused by strike-slip faults. Based from published reports and as estimated from appropriate attenuation relations, peak ground accelerations of 0.35g, 0.45g and 0.50g for the damsite were used for this study. Both simplified and finite element methods were used to determine the maximum crest acceleration and first natural period of the dam required by the MAKDISI and SEED ( 1977) method. The values obtained by the two methods are in reasonable agreement, though the simplified method is somewhat less conservative. Four potential slip circles, 2 upstream and 2 downstream, were analyzed. The results of the permanent deformation analysis shows relatively small deformations at the deep slip circles. Somewhat larger deformations were obtained at the shallow slip circles indicating that these are the more critical. Estimated pennanent deformations ranging from 0 to 21 centimeters and 0 to 3 8 centi-meters for all the input motions were obtained using the results of the simplified analysis and the dynamic finite element analysis, respectively, as input into the MAKDISI and SEED (1 977) method. These results are in generally good agreement with the obse1ved performance of the dam, which showed no signs of slope instability or deformation as a result of the eaithquake. Slope movement may have contributed to the 26 centimeters of observed settlement of the dam crest, but with the transverse cracks, it is likely the result of densification of the dam. Even though the MAKDISI and SEED (1977) simplified method was developed for clams in the height range of 30 to 60 meters, the reasonably good agreement between the estimated deformations and observed pe1formance of the I 07-meter high Pantabangan Main Dam indicate that the method may be valid for higher dams though additional case histories with more complete data should be analyzed. In addition, the close agreement between the estimated seismic response of the dam using MAKDISI and SEED (l 977) simplified iterative procedure and the dynamic finite element method indicate that the simpler method, in some cases, may be used in lieu of the more complicated dynamic finite element method. However, it should be kept in mind that the simpler method was, in (iii ) fact, less conservative. This comparison should also be checked against case histories with more complete data. |
| Year | 1996 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-95-08 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Ashford, Scott A. |
| Examination Committee(s) | Prinya Nutalaya ;Bergado, Dennes T. ;Pennung Warnichai |
| Scholarship Donor(s) | Government of Spain; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 1996 |