Modeling Seismic Vulnerability of Heritage Church Structure Using Terrestrial Lidar Data: A Case Study

Indian heritage structures display exceptional detail, adorned with numerous sculptures that offer insights into the nation's diverse cultural heritage and artistic legacy. Most of the regions in India are in seismically active zones; therefore, seismic assessment of heritage structures is essential for identifying structural weaknesses, potential points of failure, and areas requiring reinforcement. At the same time, assessing the seismic vulnerability of heritage structures in India faces a significant challenge due to the lack of detailed digital data regarding the structures' geometry, size, and dimensions. Many Indian heritage structures were constructed several decades ago, and therefore, traditional construction drawings in digital formats are often unavailable or nonexistent. To address this issue, we attempted a terrestrial lidar scanner (TLS) survey to collect comprehensive digital data concerning heritage structures' geometry, size, and dimensions. Further, the scanned data was transformed into structured AutoCAD drawings, which were the necessary inputs for comprehensive structural simulations and seismic assessments using ANSYS finite element modeling. The structural analysis encompassed seven load combination scenarios, adhering to site conditions and the code provisions of the IS:1893 (Part 1)–2002. The permissible compressive strength and tensile strength of the structure were determined to be 6.760MPa and 0.676MPa, respectively. The structural analysis revealed a maximum compressive strength of 2.630 MPa and a tensile strength of 1.980 MPa. Compared with the permissible stress limits, it was evident that the structure remains safe under site conditions in compression. However, vulnerability was observed in tension, where longer-span walls estimate high vulnerability compared to shorter-span walls, and the height of a wall significantly influences its vulnerability, with higher walls proving more susceptible to lateral seismic forces than lower ones. The structure under study is safe for existing loading or site conditions but vulnerable to seismic loads. Results indicate the potential of TLS in collecting crucial geometry data required for seismic vulnerability assessments of structures that do not have any digital data about their geometry.