Finite Element Analysis of In-plane Cyclic Loading on Masonry Walls with Traditional Mortars Used in Nepal Using Simplified Micro-modeling

Abstract

Masonry construction relies critically on the mechanical performance of mortar joints, especially under cyclic loading such as seismic action. This study numerically investigates the in-plane cyclic behavior of masonry walls built with cement, lime-surkhi, and mud mortars using a validated simplified micro-modeling approach in ABAQUS. The finite element model demonstrates strong agreement with experimental benchmarks, replicating load-displacement response, crack propagation, and stress redistribution with a root mean square error of 1.3%. Under cyclic loading, each mortar type exhibited distinct degradation patterns quantified by key metrics: cement mortar showed high initial stiffness ( 170 kN/mm) but rapid stiffness loss of approximately 75% within the first 1 mm displacement, indicating swift yielding despite good energy dissipation. Lime-surkhi mortar exhibited moderate ductility with a gradual stiffness reduction from 25 kN/mm to 5 kN/mm over 4 mm displacement. Mud mortar demonstrated negligible structural capacity, with brittle failure occurring at 15 kN and 3 mm displacement, constant low stiffness ( 5 kN/mm), and minimal energy dissipation. Analysis of equivalent plastic strain (PEEQT) and tensile damage (DAMAGET) provided further insight into mortar-specific damage evolution. These quantitative findings offer a clear performance hierarchy to inform the resilient design and restoration of masonry structures, particularly those of cultural and historical significance.