Seismic Performance Evaluation of Two-story Dhajji-dewari Traditional Structure

Abstract

ABSTRACT Experimental and numerical studies performed on traditional timber-frame masonry buildings have confirmed excellent deformability of timber structure; however, observations from dynamic shake table tests and earthquakes have revealed the potential hazard of stone falls poses a risk for occupants to get injured. This research presents a seismic performance evaluation study carried out on a traditional two-story Dhajji-Dewari structure having reduced diagonal braces for economizing construction. Moreover, one in-plane wall and one out-of-plane wall were retrofitted with typical steel wire mesh to control dislodging and fall of infill stones. Shake table tests were performed on a representative 1:3 reduced scale test model. The testing was performed using natural acceleration time history with multi-level excitations. The structure damage mechanism was observed with increasing intensity of base motion. The fundamental dynamic properties like frequency, damping, and acceleration amplification factors were obtained. The structure lateral force-deformation capacity curve was derived and bi-linearized to compute the structure ductility, overstrength, response modification factors (approximated to 3.0), and to develop structural global performance levels (i.e. roof drift limits, the corresponding base shear coefficients, and the wall damage states). A simplified procedure was also presented for the global seismic performance assessment of the Dhajji-Dewari structure in various seismic zones. The overall behavior of the model was observed to be good; however, the Immediate Occupancy and Life Safety limit states were primarily governed by the falling of infill rubbles from walls without steel wire mesh. The proposed steel wire mesh negligibly contributes to the lateral stiffness and strength of the structure and primarily prevented the dislodging and fall of stones. The proposed response modification factor can be used for the seismic analysis of structures using an elastic model to compute design forces for timber members and connection fasteners.