SEISMIC ANALYSIS OF STONE MASONRY WITH MUD MORTAR: A CASE STUDY OF CHITLANG DWELLINGS

Abstract

Nepal's masonry heritage, shaped by its seismic, architectural, and cultural context, was highly vulnerable to earthquakes, as evidenced by the 2015 Gorkha earthquake. This study investigates the SMM structure's seismic performance, structural integrity, and mechanical properties focusing on Chitlang village in central Nepal. A reconnaissance survey identified two building types-three-story with an attic (Building 1) and one-story with an attic (Building 2). Non-destructive tests were conducted alongside laboratory tests of construction materials. Results indicate the compressive strength of stone and mortar was determined to be 62.8 MPa and 1.37 MPa respectively. An ambient vibration test using a velocimeter revealed natural frequencies of 3.27 Hz for Building 1 and 6.21 Hz for Building 2. Macro modelling for non-linear static analysis was performed using FEM-based software (Abaqus) to generate pushover curves based on the concrete damage plasticity (CDP) failure criteria. The capacity and response spectrum curves were used to obtain the performance point. The performance point of the structure observed in this study indicates that the structure's current state cannot adequately withstand higher seismic demands, which results in a high probability of structural failure or collapse under such conditions. Observed damage at performance points (displacement demand) includes out-of-plane wall separations, in-plane wall failures, shear cracks, and shear sliding failures that conclude the seismic vulnerability of SMM structures in Chitlang village.