Publications

DOI :- doi.org/10.5459/bnzsee.1733

ABSTRACT:

Nepal lies within the Himalayan seismic belt, making it one of the most earthquake-prone regions globally. Non-engineered masonry structures, though widely used, are highly vulnerable to seismic disasters. Replacing these structures is impractical and culturally insensitive due to their deep traditional and cultural significance. Retrofitting is a practical and culturally appropriate approach to enhance a building’s strength and safety against earthquakes. This study evaluates retrofitting and reinforcement techniques for unreinforced masonry (URM) structures in Nepal’s mid-Himalayan region through numerical modelling, non-linear static analysis, and fragility assessment. Pushover analysis revealed that reconstruction models significantly improve base shear capacity compared to the URM model. Although gabion wire retrofitting has a limited effect at the initial stage, it significantly improves strength at larger displacements. Vertical reinforcements and horizontal bands in the reconstruction model consistently enhance performance. The URM model exhibits concentrated cracking near openings and corners, while the retrofitted model improves stress distribution and reduces crack widths. Additionally, the reconstruction model confines cracks within bands, preventing vertical propagation and ensuring superior structural integrity. Fragility curves reveal that reinforcement significantly enhances seismic performance, as the retrofitted model improves resistance across damage states, with exceptional collapse resistance due to its ductility, allowing energy absorption and delayed failure. The reconstruction model offers consistent protection with lower probabilities of damage across all states, underscoring its reliability during seismic events. Although the reconstruction model incurs higher costs than the retrofitted model due to its extensive reinforcement features, both models provide substantial seismic benefits compared to the base URM model.

DOI :- doi.org/10.3126/joeis.v5i1.93493

ABSTRACT:

Masonry structures in earthquake-prone areas are highly vulnerable because they are often built with weak materials, poor detailing, and limited maintenance, yet their seismic behavior is still not well studied. Damping is one of the parameters that influences seismic performance. It plays a critical role in energy dissipation, but its effect on masonry fragility is not fully understood. This study focuses on the influence of Rayleigh damping variation on the seismic fragility of unreinforced masonry (URM) and reinforced masonry (RM) buildings using a numerical macro- modeling approach. Nonlinear dynamic responses were analyzed under damping ratios ranging from 1% to 6%, and incremental dynamic analyses (IDA) were performed to generate corresponding fragility curves for each damping level. Results show that with an increase in damping ratios there was a reduction in roof displacements and overall seismic response, with URM showing strong sensitivity to Rayleigh damping variation. In contrast to this, RM structures exhibited reduced sensitivity, with damping effects decreasing toward collapse states. Across all damage states, reinforced masonry consistently outperformed unreinforced masonry. These findings showed the need for site- and material-specific damping characterization for URM, whereas standard guideline- based damping ratios are generally sufficient for RM, even at collapse-level fragility. The study highlights the importance of evaluating damping sensitivity in seismic fragility assessments and contributes to improving the reliability of numerical modeling for masonry structures.

ABSTRACT:

The seismic vulnerability assessment of Bindhyabasini Temple, a 250-year-old stone unreinforced masonry structure in Nepal, is presented in this paper. The study encompasses both qualitative and quantitative evaluations. Qualitative assessments involved rapid visual screening and empirical vulnerability index methods, supported by field visits and interviews with locals and the temple committee. Quantitative assessments entailed computer software-based building design and seismic behaviour evaluation through time history analysis. Following both evaluations, a vulnerability curve was generated and a checklist was filled. The vulnerability curve showed the expected damage at different intensities which may be slight, moderate, and extensive damage grade. The structure is vulnerable to both tension and shear in the openings and dome-wall connection. This research serves as a valuable resource for assessing seismic vulnerability in similar building typologies.

DOI :- doi.org/10.3126/joeis.v3i1.67094

ABSTRACT:

Nepal is located in a seismically active zone and masonry structures are widely constructed throughout the country. Lwang Village a popular tourist destination in Western Nepal contains several masonry houses. This study aims to assess the vulnerability of these buildings using the vulnerability index method. Data from 24 houses were analysed resulting in a mean Iv of 71.3. A vulnerability curve was subsequently plotted to evaluate the potential damage under earthquake scenarios similar to the Jajarkot and Gorkha earthquakes. The analysis indicated that during an earthquake of intensity comparable to the Jajarkot event, a significant portion of buildings would experience moderate to heavy damage. In addition, an earthquake similar to the Gorkha event would result in very heavy damage to near collapse for many structures. Specifically, 45.83% of the buildings are expected to suffer heavy damage, and 50% could near collapse during an Intensity X event. These findings highlight the urgent need for targeted strengthening measures to enhance the seismic resilience of buildings in Lwang Village, thereby safeguarding both the local community and the area’s touristic value.