Strut Method for the Analysis of Confined Masonry Structure with Opening

Confined masonry construction (CM) is an efficient earthquake-resistant structural system that consist of masonry walls as the main structure and RC tie column and beam as confining elements. Despite the growing application of CM for residential building, its analytical method is still inconclusive. Researchers have proposed Strut and Tie and V-D strut method, but it does not specifically cover CM wall with opening. In this study, a strut method was proposed for the analysis of CM wall with confined opening. Prior to development of strut model, shell model was created using layered shell element, to be validated using test results by others. The shell model was adjusted to match the load-deformation curve of test results. The strut models for various centric opening ratio were made to match the stiffness of the valid shell models to obtain relationship between opening ratio, strut dimension and modifying factor for strut axial area. All models were analyzed using static pushover to obtain non-linear P-d curves of the models, without vertical load. The effect of confinement on the wall’s opening and opening type were also investigated. Analysis results show that the responds of shell models with reduced elastic moduli produce responds that mimic the test results well. Correspond to the validated shell model, strut models with its dimensions and axial area modifying factor for the strut was proposed for the analysis of CM wall with various opening ratio. The effect of opening confinement is significantly increases the stiffness of the wall, but different opening type of the same ratio slightly change the CM responds. Nevertheless, the crack initiated on the corners of opening will be halted by the confining elements