System Identification and Finite Element Modelling of Damaged Bal Mandir Monument in Kathmandu After the 2015 Gorkha Earthquake

Rupakhety, Rajesh; Gautam, Dipendra; Adhikari, Rabindra; Jha, Pratyush; Bhatt, Lalit; Baruwal, Rewati

doi:10.1007/978-3-030-90788-4_21

Cited by 5 publications

(2 citation statements)

References 6 publications

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“…Rupakhety et al considered "Bal Mandir," which is an aggregate masonry complex located in Kathmandu, Nepal, for system identification using ambient vibration records taken after the Gorkha earthquake that significantly damaged the structure. For comparison with ambient vibration, the finite element analysis was conducted and both showed a noticeable change in the dynamic properties of the building (Rupakhety et al, 2022). Khansefid et al (2022) conducted an eigenvalue and pushover analysis to assess the model properties, crack propagation patterns, and crack widths based on the base shear of the buildings.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Himalayan irregular stone masonry buildings for resilient seismic design

Khadka

Acharya²,

Acharya³

et al. 2023

Front. Built Environ.

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In the Himalayan region of Nepal, stone masonry has been used for centuries as the primary building material for structures with or without mud mortar. In three distinct remote rural villages, a thorough structural survey of approximately 223 buildings was conducted with an emphasis on their structural irregularities. The thickness of masonry walls frequently varied between floors, which caused mass irregularities. Openings in the front wall of the buildings were not symmetrical in the vertical direction, which caused in-plane discontinuity. There were also out-of-plane offset irregularities due to the cross wall on the ground floor. These buildings were irregular in many aspects and were constructed without seismic considerations. This type of construction is more susceptible to earthquakes as a result of these irregularities. In this study, a thorough examination of a typical building was conducted using construction information obtained following the 2015 Gorkha earthquake. The database for each structural typology was prepared with an emphasis on construction practice to enhance the seismic design. The use of mud/cement mortar was extremely sparse, and the use of timber bands at various heights along the height of the masonry wall and an inappropriate connection between the wall and the roof were also negligible. The three main community-learned improvements following damage were the replacement of the gable wall with a metal sheet, the reduction of individual stone masonry homes to one story, and lighter construction on the upper stories of hotel buildings. Based on regional building techniques, non-linear finite models for typical and enhanced buildings were simulated. Due to the irregular stone units, construction variability, and constrained linear behavior, stone masonry with and without mud mortar presents difficulties in conducting a detailed numerical analysis. The development of these structures using mud/cement mortar and other regional materials, with careful attention to detail, was found to have significant potential as a seismically resilient building form.

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Section: Introductionmentioning

confidence: 99%

Enhancement of Himalayan irregular stone masonry buildings for resilient seismic design

Khadka

Acharya²,

Acharya³

et al. 2023

Front. Built Environ.

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“…Ambient vibration testing is one of the efficient and economic techniques to acquire the time domain response of the structure. The use of ambient vibration-based system identification covers dynamic characterization under ambient as well as excited conditions (e. g. [7][8][9][10][11][12]). In this paper, we assess the time series data collected from a wood frame building to estimate dynamic characteristics using operational modal analysis.…”

Section: Introductionmentioning

confidence: 99%

Operational Modal Analysis of Non-Redundant Wood Frame Building

Gautam,

Olafsson,

Rupakhety

2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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For the design and assessment of structures, precise dynamic characteristics are a must. A vast array of literature regarding dynamic characteristics of RC and steel structures estimated using experimental and numerical analyses can be found in either published research as well as codal provisions. On the other hand, similar studies for structures constructed using uncommon materials are limited. This adds uncertainties in the design and assessment of structures as experimental studies prior to construction or assessment are rather unpragmatic. We address a unique issue that sheds light on the identification of dynamic characteristics of a 12.8 m tall non redundant wood frame building. The building has two bays along the longer direction and one bay along the shorter direction. The columns in the buildings are made up of Sal timber (hardwood). We conducted ambient vibration measurements in the building near the geometrical center and performed system identification using the numerical algorithm for subspace state space system identification (N4SID) approach. Using operational modal analysis, the first mode frequencies and damping ratios of the building are estimated for the shorter (X) as well as the longer (Y) directions. The fundamental vibration frequency of the building along the X direction is found to be 1.16 Hz with a damping ratio of 3.02%. Along the Y direction, the fundamental vibration frequency was obtained as 1.26 Hz with a damping ratio of 2.84%. We have compared the results from system identification with several codal formulas used to estimate fundamental period/frequency to provide a rational basis for the selection of period-height or frequency-height relations. The results could serve as a notable reference in the formulation of guidelines that are likely to be developed in the future.

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