INVESTIGATION OF THE BEHAVIOR OF UNREINFORCED MASONRY CONCRETE BEARING WALLS USING MICRO MODELING APPROACH
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Date
2025-10-14
Authors
Abuhasan, Hadeel
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Publisher
An-Najah National University
Abstract
Unreinforced masonry concrete bearing walls (UMCBWs) were commonly used in Palestinian buildings between the 1950s and 1970s, as well as in historical architecture in Palestine and the Middle East. Although these buildings are no longer constructed today, many of them remain in service for residential and commercial purposes. Due to limited research, their seismic behavior is not well understood and requires further investigation. This study develops a numerical micro model using ABAQUS software to examine the in-plane lateral behavior of UMCBWs.
The research began by defining the wall system and using a published experimental study as a reference case study for developing and validating the micro model. The model was validated by comparing its lateral load-displacement response and damage pattern with the experimental result. The validated modeling approach was applied to the parametric study. Four main parameters were investigated, wall length, concrete thickness, axial pressure, and opening ratio, to evaluate their effects on lateral behavior. Nonlinear static general analyses were performed on fifty-six UMCBW models in ABAQUS to generate pushover curves.
The influence of these parameters on lateral strength, stiffness, ductility, and failure mode was analyzed and confirmed by the micro model results. The results showed that increasing wall length and thickness leads to higher strength and stiffness but reduces ductility. Increasing axial pressure significantly enhances lateral strength. The pressure levels were expressed as percentages of the
concrete compressive strength (f^' c). Below 15% of f'c, the effect of axial pressure on stiffness is negligible, whereas above 35% of f^' c, it significantly reduces stiffness. In addition, increasing axial pressure dramatically decreases ductility. The presence of an opening reduces strength, stiffness, and ductility, although at low axial pressures, for certain opening ratios, it can improve ductility.
The results obtained from the micro models were categorized based on axial pressure levels and subsequently used to derive equations for estimating bilinear pushover curves. These simplified equations provide a practical tool for representing the seismic response of UMCBWs and can support future assessment and rehabilitation strategies for existing buildings.