Stress-strain model for C-shape confined concrete masonry boundary elements of RM shear walls

•Reinforced Masonry Boundary Elements (RMBEs) are a kind of column added to wall ends.•Axial stress-strain response of 17 RMBEs with various aspect ratios (AR) is studied.•Stress-strain empirical model is proposed capable of predicting RMBEs axial response.•The model is calibrated using the experimental data of 33 RMBE specimens.•Model considers RMBE confinement and vertical reinf. ratios, grout strength, and ARs.