Damage Reconnaissance of Unreinforced Masonry Bearing Wall Buildings after the 2015 Gorkha, Nepal, Earthquake

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 243-273 ◽  
Author(s):  
Giuseppe Brando ◽  
Davide Rapone ◽  
Enrico Spacone ◽  
Matt S. O'Banion ◽  
Michael J. Olsen ◽  
...  
Keyword(s):  
Response Spectra ◽  
Visual Assessment ◽  
Unreinforced Masonry ◽  
Assessment Process ◽  
Gorkha Earthquake ◽  
Field Reconnaissance ◽  
2015 Gorkha Earthquake ◽  
Out Of Plane ◽  
2015 Gorkha Nepal Earthquake

This paper documents and analyzes the seismic behavior of unreinforced masonry (URM) buildings that were damaged by the 2015 Gorkha earthquake in Nepal, and reports on the performance of palaces, giving an overview on the failures suffered by significant examples of these monumental buildings. Field reconnaissance was completed through both rapid, in-situ visual assessment and state-of-the-art procedures utilizing light detection and ranging (lidar) and virtual reality (VR) technologies. Both the visual and virtual assessments were compared for 20 structures and were generally consistent; however, the virtual assessment process enabled detection of damage that could not be captured or was difficult to distinguish in the field observations. Further, both in-plane and out-of-plane mechanisms were analyzed and attributed to specific structural deficiencies that usually characterize poorly detailed masonry buildings. Moreover, wall overturning was correlated with the peculiarities of the pseudo-accelerations and rocking response spectra of the earthquake.

Seismic Vulnerability Assessment of Two Nepalese Rana Palaces

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 345-362 ◽  
Author(s):  
Hima Shrestha ◽  
Dmytro Dizhur ◽  
Rajani Prajapati ◽  
Marta Giaretton ◽  
Ivan Giongo ◽  
...  
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
Seismic Retrofitting ◽  
Gorkha Earthquake ◽  
Seismic Vulnerability Assessment ◽  
Sample Extraction ◽  
2015 Gorkha Earthquake ◽  
2015 Gorkha Nepal Earthquake

The Rana dynasty ruled Nepal from 1846 to 1951 and was responsible for the construction of a number of private and government Neoclassical- or Baroque-style palaces in Kathmandu and other parts of the country. Following the 2015 Gorkha (Nepal) earthquake, detailed damage assessments of these buildings were undertaken by local and international teams. Two case study buildings that suffered moderate structural damage are presented herein, the Kaiser Mahal Palace and the Ananda Niketan Palace. Kaiser Mahal was assessed prior to the 2015 Gorkha earthquake in order to develop potential seismic retrofitting options, and the results are compared with the damage observations made following the Gorkha earthquake. Ananda Niketan was only assessed after the Gorkha earthquake with an extensive damage evaluation, in-situ material testing and sample extraction, and the undertaking of a comprehensive detailed seismic assessment. The two case studies are presented herein, followed by a comparison between the two buildings.

scholarly journals Multiple remote-sensing assessment of the catastrophic collapse in Langtang Valley induced by the 2015 Gorkha earthquake

2017 ◽  
Vol 17 (11) ◽  
pp. 1907-1921 ◽  
Author(s):  
Hiroto Nagai ◽  
Manabu Watanabe ◽  
Naoya Tomii ◽  
Takeo Tadono ◽  
Shinichi Suzuki
Keyword(s):  
Monsoon Season ◽  
Deposition Process ◽  
Visual Interpretation ◽  
Gorkha Earthquake ◽  
Water Stream ◽  
2015 Gorkha Earthquake ◽  
Himalayan Mountain ◽  
Hazard Process ◽  
Langtang Valley

Abstract. The main shock of the 2015 Gorkha Earthquake in Nepal induced numerous avalanches, rockfalls, and landslides in Himalayan mountain regions. A major village in the Langtang Valley was destroyed and numerous people were victims of a catastrophic avalanche event, which consisted of snow, ice, rock, and blast wind. Understanding the hazard process mainly depends on limited witness accounts, interviews, and an in situ survey after a monsoon season. To record the immediate situation and to understand the deposition process, we performed an assessment by means of satellite-based observations carried out no later than 2 weeks after the event. The avalanche-induced sediment deposition was delineated with the calculation of decreasing coherence and visual interpretation of amplitude images acquired from the Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR-2). These outline areas are highly consistent with that delineated from a high-resolution optical image of WorldView-3 (WV-3). The delineated sediment areas were estimated as 0.63 km2 (PALSAR-2 coherence calculation), 0.73 km2 (PALSAR-2 visual interpretation), and 0.88 km2 (WV-3). In the WV-3 image, surface features were classified into 10 groups. Our analysis suggests that the avalanche event contained a sequence of (1) a fast splashing body with an air blast, (2) a huge, flowing muddy mass, (3) less mass flowing from another source, (4) a smaller amount of splashing and flowing mass, and (5) splashing mass without flowing on the east and west sides. By means of satellite-derived pre- and post-event digital surface models, differences in the surface altitudes of the collapse events estimated the total volume of the sediments as 5.51 ± 0.09  ×  106 m3, the largest mass of which are distributed along the river floor and a tributary water stream. These findings contribute to detailed numerical simulation of the avalanche sequences and source identification; furthermore, altitude measurements after ice and snow melting would reveal a contained volume of melting ice and snow.

scholarly journals The Performance of Slender Monuments during the 2015 Gorkha, Nepal, Earthquake

2017 ◽  
Vol 33 (1_suppl) ◽  
pp. 321-343 ◽  
Author(s):  
Anjali Mehrotra ◽  
Matthew DeJong
Keyword(s):  
Ground Motion ◽  
Low Frequency ◽  
Kathmandu Valley ◽  
Discrete Element Modeling ◽  
Frequency Content ◽  
Gorkha Earthquake ◽  
Long Period ◽  
2015 Gorkha Earthquake ◽  
Long Period Ground Motion ◽  
2015 Gorkha Nepal Earthquake

This paper studies damage to a few specific monuments in the Kathmandu Valley that were either partially or completely destroyed during the 2015 Gorkha earthquake. Three of these structures—namely, the Basantapur Column, the Dharahara Tower, and the Narayan Temple—were modeled both analytically using rocking dynamics and computationally using discrete element modeling (DEM). The results emphasize the importance of large low frequency content within the ground motion, demonstrating that the Dharahara Tower could have collapsed due to the primary long-period ground motion pulse alone. In addition, comparison of analytical and computational modeling to the observed response enables evaluation of structural behavior, including discussion of the importance of elastic amplification and column embedment on performance during the earthquake.

scholarly journals In Situ Out-of-Plane Testing of Unreinforced Masonry Cavity Walls in as-Built and Improved Conditions

Structures ◽  
2015 ◽  
Vol 3 ◽  
pp. 187-199 ◽  
Author(s):  
Kevin Q. Walsh ◽  
Dmytro Y. Dizhur ◽  
Jalil Shafaei ◽  
Hossein Derakhshan ◽  
Jason M. Ingham
Keyword(s):  
Unreinforced Masonry ◽  
Out Of Plane

scholarly journals Rapid Terrain Assessment for Earthquake-Triggered Landslide Susceptibility With High-Resolution DEM and Critical Acceleration

2021 ◽  
Vol 9 ◽  
Author(s):  
Season Maharjan ◽  
Kaushal Raj Gnyawali ◽  
Dwayne D. Tannant ◽  
Chong Xu ◽  
Pascal Lacroix
Keyword(s):  
High Resolution ◽  
Landslide Susceptibility ◽  
Earthquake Ground Motion ◽  
Depth Information ◽  
Gorkha Earthquake ◽  
Ground Acceleration ◽  
Critical Acceleration ◽  
Field Reconnaissance ◽  
2015 Gorkha Earthquake ◽  
Glaciated Valley

Earthquake ground motion often triggers landslides in mountainous areas. A simple, robust method to quickly evaluate the terrain’s susceptibility of specific locations to earthquake-triggered landslides is important for planning field reconnaissance and rescues after earthquakes. Different approaches have been used to estimate coseismic landslide susceptibility using Newmark’s sliding block model. This model requires an estimate of the landslide depth or thickness, which is a difficult parameter to estimate. We illustrate the use of Newmark sliding block’s critical acceleration for a glaciated valley affected by the 2015 Gorkha earthquake in Nepal. The landslide data came from comparing high-resolution pre- and post-earthquake digital elevation models (DEMs) derived from Spot 6/7 images. The areas where changes were detected provided an inventory of all the landslides triggered by the earthquake. The landslide susceptibility was modeled in a GIS environment using as inputs the pre-earthquake terrain and slope angles, the peak ground acceleration from the 2015 Gorkha earthquake, and a geological map. We exploit the depth information for the landslides (obtained by DEM difference) to apply the critical acceleration model. The spatial distribution of the predicted earthquake-triggered landslides matched the actual landslides when the assumed landslide thickness in the model is close to the median value of the actual landslide thickness (2.6 m in this case). The landslide predictions generated a map of landslide locations close to those observed and demonstrated the applicability of critical acceleration for rapidly creating a map of earthquake-triggered landslides.

scholarly journals Seismic assessment of out-of-plane loaded unreinforced masonry walls in multi-storey buildings

2014 ◽  
Vol 47 (2) ◽  
pp. 119-138 ◽  
Author(s):  
Hossein Derakhshan ◽  
Dmytro Y. Dizhur ◽  
Michael C. Griffith ◽  
Jason M. Ingham
Keyword(s):  
Spectral Response ◽  
Response Spectra ◽  
Worked Examples ◽  
Unreinforced Masonry ◽  
Acceleration Response ◽  
Single Degree Of Freedom ◽  
Floor Response Spectra ◽  
Stiffness Properties ◽  
Out Of Plane ◽  
Ground Motion Records

A procedure is proposed to evaluate the dynamic out-of-plane stability of cracked unreinforced masonry (URM) walls located in multi-storey URM buildings. The equations of dynamic motion are derived from first principles and representative single-degree-of-freedom (SDOF) models are proposed. The models have nonlinear stiffness properties that correspond to the restoring gravitational forces. A method is suggested to transform the nonlinear problem to a corresponding linear equivalent so that conventional spectral methods can be used to calculate wall response. The dynamic interaction between the URM building as the main structural system and the out-of-plane loaded walls as secondary elements is addressed by developing floor response spectra. Several buildings were assumed in a parametric study and subjected to code-compatible ground motion records. The absolute acceleration response at floor levels was calculated and the response spectra for that modified acceleration were subsequently obtained. The results from the study suggest that modifications should be made to the equations proposed for the Parts response spectra in the New Zealand seismic loading standard, NZS 1170.5:2004, in order to calculate the spectral response of out-of-plane loaded URM walls. Several worked examples are presented to demonstrate application of the procedure.

scholarly journals In Situ Out-of-Plane Testing of As-Built and Retrofitted Unreinforced Masonry Walls

2014 ◽  
Vol 140 (6) ◽  
pp. 04014022 ◽  
Author(s):  
Hossein Derakhshan ◽  
Dmytro Dizhur ◽  
Michael C. Griffith ◽  
Jason M. Ingham
Keyword(s):  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Out Of Plane

scholarly journals Response Spectra-Based Post-Earthquake Rapid Structural Damage Estimation Approach Aided with Remote Sensing Data: 2020 Samos Earthquake

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 14
Author(s):  
Onur Kaplan ◽  
Gordana Kaplan
Keyword(s):  
Remote Sensing ◽  
Damage Assessment ◽  
Structural Damage ◽  
Estimation Method ◽  
Remote Sensing Data ◽  
Response Spectra ◽  
Assessment Process ◽  
Damage Estimation ◽  
Sensing Data

Effective post-event emergency management contributes substantially to communities’ earthquake resilience, and one of the most crucial actions following an earthquake is building damage assessment. On-site inspections are dangerous, expensive, and time-consuming. Remote sensing techniques have shown great potential in localizing the most damaged regions and thus guiding aid and rescue operations in recent earthquakes. Furthermore, to prevent post-earthquake casualties, heavily damaged, unsafe buildings must be identified immediately since in most earthquakes, strong aftershocks can cause such buildings to collapse. The potential of the response spectrum concept for being associated with satellite-based remote sensing data for post-earthquake structural damage estimation was investigated in this study. In this respect, a response spectra-based post-earthquake structural damage estimation method aided by satellite-based remote sensing data was proposed to classify the buildings after an earthquake by prioritizing them based on their expected damage levels, in order to speed up the damage assessment process of critical buildings that can cause casualties in a possible strong aftershock. A case study application was implemented in the Bayrakli region in Izmir, Turkey, the most affected area by the Samos earthquake, on 30 October 2020. The damage estimations made in this research were compared with the in situ damage assessment reports prepared by the Republic of Turkey Ministry of Environment and Urbanization experts. According to the accuracy assessment results, the sensitivity of the method is high (91%), and the necessary time spent by the in situ damage assessment teams to detect the critical buildings would have been significantly reduced for the study area.

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