Construction Practices and Seismic Vulnerability of Buildings in the Indian Himalayan Region: A Case Study

Due to rapid growth in tourism and other economic activities, several small cities and towns in the Indian Himalayan region are facing problems of unplanned construction and extended use of deteriorating old structures. Despite being in the most active zone of seismic activity, significant nonengineered construction is practiced in this region. Hence, it becomes essential to examine the existing engineered and nonengineered building typologies and assess their vulnerabilities against earthquake shaking. This study presents typical engineered and nonengineered construction practices observed through a survey of 1,009 buildings located within Mandi, a small town in the lap of the great Himalayas in the Indian state of Himachal Pradesh. An attempt is made to identify the typical building typologies, visible structural irregular features and their seismic vulnerability. A few building typologies predominantly prevail in the northern zone of the Indian Himalayan region are identified. Rapid visual screening (RVS) of the surveyed buildings is performed using different existing guidelines. It is observed that a substantial number of buildings with hybrid typology (stone masonry mixed with brick masonry or reinforced concrete) prevail in the study area. It is also observed that the seismic vulnerability, as per the adopted RVS guidelines, of the majority of the buildings is high, indicating urgent demand to safeguard the vulnerable built environment and develop the framework for a seismic resilient society. It is further concluded that use of region-specific vulnerability attributes can improve the segregation of buildings based on expected damage. The seismic assessment of large existing building stock through rapid visual screening (RVS) is important for preliminary evaluation. This study presents crucial insights into seismic vulnerability assessment and earthquake-resistant construction practices in the Indian Himalayan region. It identifies new building typologies, prevalent poor construction practices, and critical vulnerable attributes in the case study region. These findings hold significant practical implications for various stakeholders, including engineers, researchers, policymakers, and practitioners. By understanding the ground conditions of construction practices, building typologies, and vulnerability attributes, stakeholders can develop robust RVS methodologies which accurately assess their seismic vulnerability for planning effective seismic risk mitigation strategies and promote earthquake-resistant construction practices. Identifying new building typologies will encourage future research to quantify vulnerability through numerical studies, experimental investigation, and field data.