<p>This paper presents the effects of 3D conical topography on the pseudo-dynamically simulated ground motion characteristics. The simulation of pseudo-dynamic ground motion has been carried out using a fourth-order accurate staggered-grid time-domain 3D finite-difference method. In the case of numerical simulations, the radiation of seismic energy from the rupture plane as per Brune&#8217;s model as well as avoiding the coherency effects is a challenging job for the simulators. The randomization of slip, rise-time, and peak-time of the source time function and the rupture arrival time, as well as the incorporation of fault-roughness and damage zone, play important roles in seismic energy release from the rupture plane as well as in the reduction of currency effects on the high-frequency seismic radiations. Firstly, the ground motions have been simulated for a hypothetical strike-slip Mw 6.0 earthquake. The efficacy of the presented code has been validated with a good match of the computed average pseudo-spectral acceleration (PSA) using the simulated ground motion with that obtained using NGA-West2 GMPEs in the frequency range 0.1&#8211;5.0 Hz. The code has been able to correctly incorporate the rupture directivity effect. Further, the effect of 3D conical topography has been estimated with azimuthal coverage of receivers. The effect of the direction of the source on the topographic amplification has also been estimated. It has been observed that topography plays an important role in the amplification of earthquake ground motion. Also, the direction of the source plays an important role in estimating the pattern of topographic amplification.</p>
The paper presents the quantification of site-city-interaction (SCI) effects on the responses of buildings of a city and free field motion under realistic earthquake loading for the economic development of a smart city. The state of the art pseudo-dynamic earthquake rupture is implemented in the existing fourth-order viscoelastic staggered-grid SH-wave finite-difference program, and simulated results validated. SH-wave responses of various homogeneous and heterogeneous cities situated on horizontal sediment layer as well as in 2D heterogeneous basins are simulated and analyzed for different dynamic parameters of the buildings. The simulated SCI effects using realistic earthquake loading reveals a reduction of transfer function (TF) of buildings in a wide frequency bandwidth. This finding is conflicting with the reported splitting of bandwidth of the FoSB in the past SCI studies, carried out using simple plane incident wave-front with a single zero-phase wavelet. The obtained largest SCI effects on a building was highly dependent on the building type, city and basin heterogeneity in contrast to the general perception that it should be maximum at centre of city. It is also obtained that SCI effects are always beneficial to buildings when fundamental frequency of building on rock FoSR <1.4FoB( FoB is the fundamental frequency of basin/sediment layer). The obtained reduction of of building of city as well as free field motion due to the effects of SCI corroborates with the past SCI studies. The increase of coupling between the buildings and basin due to an increase of building density causes an increase of SCI effects on the responses of both the buildings and free field motion. The SCI effects in the case of buildings with low damping are beneficial during an earthquake. It is recommended that the smart city should be homogeneous in nature and of buildings should be less than around 1.4 times the of the underlying basin/sediment deposit and buildings should preferably be a steel one.
Slip distribution model has been developed for 15 th January 1934 Bihar-Nepal earthquake of M w 8.1 has been developed through stochastic model. The spatial variability of slip on the rupture plane is simulated as a random field with correlation lengths depending on the magnitude of the earthquake. The source dimensions have been computed from the scaling laws of Wells and Coppersmith (1994) and Mai and Beroza (2000). The slip distribution has been obtained from spectral synthesis method of Iguzquiza and Olma (1993) for both the source dimension. The slip distribution of each of the 5 samples has been shown in form of contour plots. The average slip estimated using different source dimension from WC and MB are 8.15 m and 12.96 m respectively. The simulated slip models developed can be used to simulate the displacement time histories of the 1934 Bihar-Nepal earthquake which can be used in seismic hazard studies in future
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