Retrofitting of an RC frame building damaged in “April 2015 Gorkha earthquake” in Kathmandu valley

It remains elusive why there was only weak and limited ground shaking in Kathmandu valley during the 25 April 2015 Mw 7.8 Gorkha, Nepal, earthquake. Our spectral element numerical simulations show that, during this earthquake, surface topography restricted the propagation of seismic energy into the valley. The mountains diverted the incoming seismic wave mostly to the eastern and western margins of the valley. As a result, we find de-amplification of peak ground displacement in most of the valley interior. Modeling of alternative earthquake scenarios of the same magnitude occurring at different locations shows that these will affect the Kathmandu valley much more strongly, up to 2–3 times more, than the 2015 Gorkha earthquake did. This indicates that surface topography contributed to the reduced seismic shaking for this specific earthquake and lessened the earthquake impact within the valley.

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Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence

Tectonophysics ◽

10.1016/j.tecto.2016.09.030 ◽

2017 ◽

Vol 714-715 ◽

pp. 146-157 ◽

Cited By ~ 18

Author(s):

S. Rajaure ◽

D. Asimaki ◽

E.M. Thompson ◽

S. Hough ◽

S. Martin ◽

...

Keyword(s):

Strong Motion ◽

Earthquake Sequence ◽

Kathmandu Valley ◽

Gorkha Earthquake ◽

2015 Gorkha Earthquake

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Influence of Staircase and Elevator Core Location on the Seismic Capacity of an RC Frame Building

Journal of Architectural Engineering ◽

10.1061/(asce)ae.1943-5568.0000274 ◽

2017 ◽

Vol 23 (4) ◽

pp. 05017007

Author(s):

Srinivasa Rao Botsa ◽

Kaustubh Dasgupta

Keyword(s):

Rc Frame ◽

Seismic Capacity ◽

Frame Building ◽

Rc Frame Building

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Seismic Performance of Multistorey RC Frame Building With The Soft Storey and Masonry Infill

International Journal of Advanced Research in Science, Communication and Technology ◽

10.48175/ijarsct-1307 ◽

2021 ◽

pp. 650-656

Author(s):

Kugan K ◽

Mr. Nandha Kumar P ◽

Premalath J

Keyword(s):

Time History ◽

Seismic Loading ◽

Rc Frame ◽

Base Shear ◽

Maximum Displacement ◽

Soft Storey ◽

Masonry Infills ◽

Frame Building ◽

History Analysis ◽

Rc Frame Building

In this study, four geometrically similar frames having different configurations of masonry infills, has been investigated. In this article attempts are made to explain the factors that impact the soft storey failure in a building are compared with different type of infill. That is Four models like RC bare frame, RC frame with brick mansonry infill, RC frame with brick infill in all the storeys exept the firstsoft storey, RC frame with inverted V bracing in the soft storey. Time history analysis has been carried out for a G+8 multistoried building to study the soft storey effect at different floor levels using E tabs software. The behavior of RC framed building with soft storey under seismic loading has been observed in terms of maximum displacement ,maximum storey drift, base shear and storey stiffness as considered structure.

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Effect of uniform temperature load on design of long reinforced concrete structures without expansion joints

Journal of Science and Technology in Civil Engineering (STCE) - NUCE ◽

10.31814/stce.nuce2021-15(3)-06 ◽

2021 ◽

Vol 15 (3) ◽

pp. 68-80

Author(s):

Pham Thai Hoan ◽

Nguyen Minh Tuan

Keyword(s):

Rc Frame ◽

Uniform Temperature ◽

Expansion Joints ◽

Rc Structures ◽

Frame Building ◽

Medium Length ◽

Building Models ◽

Temperature Load ◽

Internal Forces ◽

Rc Frame Building

This study presents an investigation on the design of long reinforced concrete (RC) structures subjected to uniform temperature load by considering three RC frame building models with different lengths of 45 m, 135 m, and 270 m using Etabs. The uniform temperature load is considered being the change from the annual average highest to lowest air temperature at the construction site in the case of unavailable temperature data of concrete. The analysis results indicate that the uniform temperature load mainly influences on the internal forces of RC members at storey 1 and slightly effects on the internal forces of RC members at storey 2. For short-length RC structures, the effect of temperature load can be ignored in the design of RC elements, whereas it must be taken into account in design of slab, beams and some column positions at storey 1 of medium-length and long RC structures without expansion joints. For the present RC frame building models, the required slab reinforcement in long direction increases about 33.4% for medium-length RC structures (135 m) and about 48.2% for long RC structures (270 m) without expansion joints. The required reinforcement for positive moment at mid-span increases from 33.7 to 39.4%, whereas the total required reinforcement for negative moment at the supports of beams increases from 19.4 to 34.9% in long direction of 270 m long RC structures without expansion joints due to uniform temperature load. Column design of long RC structures without expansion joints under uniform temperature load must be concerned, especially for columns in the corners.

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Liquefaction hazard assessment and ground failure probability analysis in the Kathmandu Valley of Nepal

Geoenvironmental Disasters ◽

10.1186/s40677-021-00203-0 ◽

2022 ◽

Vol 9 (1) ◽

Author(s):

Mandip Subedi ◽

Indra Prasad Acharya

Keyword(s):

Soil Liquefaction ◽

Kathmandu Valley ◽

Borehole Data ◽

Gorkha Earthquake ◽

Engineering Structures ◽

Liquefaction Potential ◽

Ground Failure ◽

2015 Gorkha Earthquake ◽

Scenario Earthquakes ◽

Liquefaction Hazard

AbstractDuring the 2015 Gorkha Earthquake (Mw7.8), extensive soil liquefaction was observed across the Kathmandu Valley. As a densely populated urban settlement, the assessment of liquefaction potential of the valley is crucial especially for ensuring the safety of engineering structures. In this study, we use borehole data including SPT-N values of 410 locations in the valley to assess the susceptibility, hazard, and risk of liquefaction of the valley soil considering three likely-to-recur scenario earthquakes. Some of the existing and frequently used analysis and computation methods are employed for the assessments, and the obtained results are presented in the form of liquefaction hazard maps indicating factor of safety, liquefaction potential index, and probability of ground failure (PG). The assessment results reveal that most of the areas have medium to very high liquefaction susceptibility, and that the central and southern parts of the valley are more susceptible to liquefaction and are at greater risk of liquefaction damage than the northern parts. The assessment outcomes are validated with the field manifestations during the 2015 Gorkha Earthquake. The target SPT-N values (Nimproved) at potentially liquefiable areas are determined using back analysis to ascertain no liquefaction during the aforesaid three scenario earthquakes.

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Compliance-Based Estimation of Seismic Collapse Risk of an Existing Reinforced Concrete Frame Building

10.21203/rs.3.rs-287402/v1 ◽

2021 ◽

Author(s):

Anastasios Tsiavos ◽

Pascal Amrein ◽

Nathan Bender ◽

Bozidar Stojadinovic

Keyword(s):

Earthquake Ground Motion ◽

Rc Frame ◽

Seismic Code ◽

Existing Structures ◽

Frame Building ◽

Seismic Collapse ◽

Rc Building ◽

Hazard Level ◽

Rc Frame Building ◽

Code Compliance

Abstract The seismic evaluation of existing structures is based on the determination of the damage likely to occur during the lifetime of these structures due to earthquake ground motion excitation. However, there is not a consensus about the acceptable level of seismic damage, the expected lifetime of these structures, and the seismic hazard level(s) to evaluate the structures at. This paper presents a methodology for the parametric determination of the seismic collapse risk of an existing Reinforced Concrete (RC) frame building based on its seismic code compliance, quantified by a dimensionless metric. This metric, defined as compliance factor, compares the seismic capacity of an existing structure with the seismic demand for a new structure at a predetermined hazard level. The inelastic seismic behavior of four models of the RC frame building of varying compliance was analytically investigated in this study to demonstrate the implementation of the novel methodology. The four models of the RC building were chosen to represent existing RC frame structures, designed and constructed before the introduction of the modern seismic code provisions. These four building models were excited by a group of earthquake ground motion excitations using Incremental Dynamic Analysis (IDA). The collapse probability of the four models of the RC building representing varying values of seismic code compliance was determined for two different locations corresponding to regions of moderate and high seismic hazard, thus laying the basis for the compliance-based estimation of the seismic collapse risk of existing structures.

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The 2015 Gorkha Earthquake and response of the Kathmandu Valley sediments

Journal of Nepal Geological Society ◽

10.3126/jngs.v49i1.23136 ◽

2015 ◽

Vol 49 (1) ◽

pp. 1-5

Author(s):

Sudhir Rajaure ◽

Megh Raj Dhital ◽

Lalu Prasad Paudel

Keyword(s):

Source Zone ◽

Great Earthquake ◽

Kathmandu Valley ◽

Main Central Thrust ◽

Gorkha Earthquake ◽

Ground Acceleration ◽

Low Frequencies ◽

High Frequencies ◽

Nepal Earthquake ◽

2015 Gorkha Earthquake

The Gorkha Earthquake occurred on the gently dipping part of the Main Himalayan Thrust (MHT), close to the Main Central Thrust (MCT). This earthquake possibly occurred in the source zone of the 1833 Nepal Earthquake (Mw 7.6), which occurred after 182 years. The region between the 1905 Kangra Earthquake and 1934 Bihar-Nepal Earthquake has not produced any great earthquake since the last 500 years and still remains a potential site for great earthquake(s) in future. The Kathmandu Valley witnessed moderate ground acceleration and comparatively large velocity as recorded at Kantipath during the Mw 7.8, Gorkha Earthquake. The analysis of the records show that high frequencies were damped and low frequencies were dominant over the sedimentary basin, which can be attributed to the response of the sediments underneath. Because of damping of high frequencies, the engineered, low storey buildings were less damaged and resisted the ground shaking comparatively well. However, on the other hand, the historical monument 'Dharahara' collapsed completely and the high rise apartment buildings suffered more because of the dominance of low frequencies.

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