Detailed Aseismic Survey of Public Structures Damaged by the Taiwan Chi-Chi Earthquake and the Iran Bam Earthquake

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The following conclusions were drawn from the field investigation and detailed analysis conducted on earthquake damages in the Taiwan Chi-Chi Earthquake and Iran Bam Earthquake :(1) Damage analysis was conducted on the Chang-Geng Bridge damaged by the mutual pounding of girders during the Taiwan Chi-Chi Earthquake, utilizing the results of field surveys and detailed drawings provided by the Taiwan side. The abutment of the bridge was modeled by incorporating field survey results. The nonlinear dynamic analysis with consideration for girder pounding reproduced the development process of actual damage, in which girders pounded each other after the supports had failed due to the inertia force of the superstructure, smashed into the abutment parapet, and then forced into the soil behind the abutment for about 1 m.(2) Detailed damage analysis and evaluation of aseismic capacity were conducted on the PC cable-stayed bridge damaged by the Taiwan Chi-Chi Earthquake. From the nonlinear dynamic analysis, it was found that the damage to the bottom of the RC pylon was caused by the higher-order deformation mode that appeared at the pylon. Then, from the parameter analysis, it was found that the response could be extremely large in the case of long-period structures like PC cable-stayed bridges, due to the effect of seismic waves in which long-period components are predominant.(3) Field survey was conducted on the public structures that were damaged by the Iran Bam Earthquake in December, 2003. Among the structures surveyed, damage analysis was performed specifically on the damaged bridges. The non-linear time history response analysis reproduced the development of the damage, in which RC girders pounded each other and moved on the piers after the supports had reached the maximum friction force due to the inertia force during the earthquake, causing gaps and residual displacements between girders.