Sensitivity of the strong ground motion time histories to a finite source model: A case study for the January 12, 2010 Haiti earthquake (M-w=7.0)

We analyze the waveforms generated by the January 12, 2010 Haiti earthquake (M-w=7.0) for its source characteristics. A 60 to 25 km source model is retrieved by the Kikuchi and Kanamori finite source inversion technique that uses broadband teleseismic body wave records. The derived rupture model points out unilateral rupture propagation commenced at the eastern side of the fault plane where the major seismic moment release occurred. The rupture front propagated westward and terminated at a site where the largest aftershocks occurred. Our estimates yield a seismic moment of M-o=8.17 x 10(19) N m released on a 60 km-long fault plane. A patch at the eastern side of the ruptured fault plane inferred as a region of maximum moment release

Response of the Fatih Sultan Mehmet Suspension Bridge under spatially varying multi-point earthquake excitations

The study aims at investigating the structural behavior of the Fatih Sultan Mehmet Suspension Bridge, i.e. the second Bosphorus Bridge in Turkey, under multi-point earthquake excitations, and determining the earthquake performance of the bridge based on the results obtained from this analysis. For this objective, spatially varying ground motions in triple direction were produced for each support of the bridge considering the Mw=7.4 scenario earthquakes on the main Marmara Fault. In order to simulate the ground motions, modified stochastic finite-fault technique was utilized. Taking the ground motions into account, non-linear time-history analysis was carried out, and the results obtained from the analysis were compared to those from uniform support earthquake excitation to identify the effects of multi-point earthquake excitations on the seismic performance of the bridge. From the analysis, it was determined that modal response of the towers and the deck was mostly effective on dynamic response of the entire bridge rather than other structural elements, such as cable and approach viaduct. Compared to the results obtained from simple-point earthquake excitation, noticeable axial force increase in the cable elements was obtained under multi-point earthquake excitation. The changes at the main cable and the side span cable were determined as 21\% and 18\%, respectively. This much increase in the cable elements led to increase in axial force at the towers and in shear force at the base section of the tower column. These changes in the structural elements were closely related to response of the deck and the towers since they had considerable contribution to response of the entire bridge. Based on the findings from the study, spatially varying ground motions has to be considered for long span suspension bridges, and the multi-support earthquake analysis should be carried out for better understanding and obtaining reliable results necessary for retrofitting and performance evaluation. (C) 2016 Elsevier Ltd. All rights reserved

Multi-Point Earthquake Response Of The Bosphorus Bridge To Site-Specific Ground Motions

The study presents the earthquake performance of the Bosphorus Bridge under multi-point earthquake excitation considering the spatially varying site-specific earthquake motions. The elaborate FE model of the bridge is firstly established depending on the new considerations of the used FEM software specifications, such as cable-sag effect, rigid link and gap elements. The modal analysis showed that singular modes of the deck and the tower were relatively effective in the dynamic behavior of the bridge due to higher total mass participation mass ratio of 80%. The parameters and requirements to be considered in simulation process are determined to generate the spatially varying site-specific ground motions. Total number of twelve simulated ground motions are defined for the multi-support earthquake analysis (Mp-sup). In order to easily implement multi-point earthquake excitation to the bridge, the practice-oriented procedure is summarized. The results demonstrated that the Mp-sup led to high increase in sectional forces of the critical components of the bridge, especially tower base section and tensile force of the main and back stay cables. A close relationship between the dynamic response and the behavior of the bridge under the Mp-sup was also obtained. Consequently, the outcomes from this study underscored the importance of the utilization of the multi-point earthquake analysis and the necessity of considering specifically generated earthquake motions for suspension bridges

Near-Fault Earthquake Ground Motion and Seismic Isolation Design

Seismic isolation is one of the most reliable passive structural control techniques with adequately established standards for the earthquake protection of structures from earthquakes. However, it has been shown that the seismic isolation systems may not function the best for the near-fault ground motions, since in the proximity of a capable fault, the ground motions are significantly affected by the rupture mechanism and may generate high demands on the isolation system and the structure. In fact, several earthquake resistant design codes state that the seismically isolated structures located at near-fault sites should be designed by considering larger seismic demands than the demand on structures at far-field sites. When the fault ruptures in forward direction to the site most of the seismic energy arrives in coherent long-period ground velocity pulses. The ground-motion prediction equations (GMPEs) typically cannot account for such effects with limited distance metrics and lack adequate data at large magnitudes and near distances. For the reliable earthquake design of the isolated structure in near fault conditions that meets the performance objectives, the 3D design basis ground motion(s) need to be appropriately assessed. Measures in the design of the isolation system, such as modifications in the stiffness and damping characteristics, as well as in the limitation of vertical effects are needed. The behavior of the base-isolated buildings under near-fault (NF) ground motions with fling-step and forward-directivity characteristics are investigated with a rational assessment of design-basis near-fault ground motion, are investigated in a parametric format. The parametric study includes several variables, including the structural system flexibility; number of stories; isolation system characteristic (yield) strength, and the isolation periods related to the post-elastic stiffness. Furthermore, the effect of additional damping by viscous dampers were tested for some selected cases. Important findings observed from the parametric performance results and the overall conclusions of the study are provided.Politecnico TorinoWOS:0009635759000092-s2.0-85148693217Conference Proceedings Citation Index – ScienceProceedings PaperUluslararası işbirliği ile yapılmayan - HAYIRNisan2023YÖK - 2022-2

Rapid earthquake hazard and loss assessment for Euro-Mediterranean region

The almost-real time estimation of ground shaking and losses after a major earthquake in the Euro-Mediterranean region was performed in the framework of the Joint Research Activity 3 (JRA-3) component of the EU FP6 Project entitled "Network of Research Infra-structures for European Seismology, NERIES". This project consists of finding the most likely location of the earthquake source by estimating the fault rupture parameters on the basis of rapid inversion of data from on-line regional broadband stations. It also includes an estimation of the spatial distribution of selected site-specific ground motion parameters at engineering bedrock through region-specific ground motion prediction equations (GMPEs) or physical simulation of ground motion. By using the Earthquake Loss Estimation Routine (ELER) software, the multi-level methodology developed for real time estimation of losses is capable of incorporating regional variability and sources of uncertainty stemming from GMPEs, fault finiteness, site modifications, inventory of physical and social elements subjected to earthquake hazard and the associated vulnerability relationships