The IAStructE–IIIT Hyderabad Student Chapter organized an expert lecture on “Seismic Damage Gradation for Structural Brick Masonry Buildings” on 26th August 2025 in online mode. The lecture was delivered by Dr. S. R. Balasubramanian, Principal Scientist, CSIR-SERC, Chennai. The session provided an in-depth discourse on advanced methodologies for earthquake damage assessment and structural modelling of masonry buildings. Dr. Balasubramanian began by highlighting the limitations of subjective damage classifications such as “minor” and “severe,” and emphasized the necessity of adopting objective parameters including crack width, volume loss, and story drift. He particularly underscored the significance of story drift, critiquing the use of fixed damage thresholds and advocating instead for deformational control, which provides a more precise framework for damage assessment. In this context, he introduced the concept of story shear modelling as a valuable tool to evaluate the seismic response of building components and to facilitate cost-effective repair strategies.

The lecture further explored failure mechanisms in masonry structures, with distinctions drawn between sliding shear modes and diagonal tension modes. Dr. Balasubramanian stressed the importance of deriving capacity curves for individual components, obtained by multiplying displacement values with utility ratios, and explained the procedure for aggregating these into a total capacity curve for the entire structure. He elaborated on the non-linear behaviour of capacity curves, noting that the weakest link within a subsystem typically undergoes plastic deformation, thereby influencing displacement responses. Clarifications were also provided on the differential behaviour of forces and displacements in parallel and series systems, with special reference to sliding, rocking, and diagonal tension mechanisms in masonry.

During the interactive discussion, Dr. Balasubramanian addressed pertinent queries regarding the reliability of drift ratios in real-world assessments, retrofitting strategies informed by the demand and capacity relationship, and the criteria governing allowable opening limits in masonry walls. In conclusion, the lecture offered a comprehensive perspective on seismic damage gradation for brick masonry buildings. Dr. Balasubramanian’s scholarly insights on deformational control, failure mechanisms, and dynamic modelling contribute significantly to advancing the understanding of seismic resilience and serve as a valuable guide for the development of effective retrofitting strategies in masonry structures.