Vulnerability Assessment of All Saints’ Church - a Unique Heritage Building in Bengaluru

Increasing infrastructure projects in mega-cities are leading to greater vulnerability of heritage structures situated in the proximity. Heavy construction activities such as tunnelling, pile driving, deep excavation, movement of heavy vehicles, deep foundation, etc., are common in such projects. A combination of these activities leads to unintended distress in heritage structures, especially unreinforced masonry buildings. It is important to assess the structural health and vulnerability of such buildings. This would help in deciding on conservation strategies, including possible retrofitting of the structure. Bengaluru is one such mega-city which is bestowed with numerous heritage buildings, many of which are in proximity to the on-going metro project. All Saints’ church is one such unique single-storied unreinforced masonry building neighbouring one of the underground metro stations proposed. The church was designed by Robert Fellowes Chisholm, a legend in architecture and pioneer of the Indo- Saracenic style, about 150 years ago. Its structural and architectural uniqueness is certainly worthy to be conserved. This paper brings out the details of the attempt made to assess the vulnerability of this structure due to possible lateral loads caused by ground motions induced by construction activities. An investigation has been made to collect the structural details required to model and analyse the structure. An attempt has been made to identify the regions in the load-bearing elements of the building which could experience higher levels of stresses due to lateral loads, using general purpose finite element software. During the study, it is observed that there are certain unique structural elements that have been robustly configured into the architectural features and thus rendered the building healthy despite its age. It is concluded that these unique structural elements need to be carefully monitored and protected to conserve the heritage building.