Improving Torsional Rigidity and Seismic Performance of Tunnel Form Building Structures

Abstract

Tunnel form buildings, which have shear-wall dominant structural systems, are usually built in countries exposed to substantial seismic risk and very commonly used because of its fast construction technique and low cost. Very limited research has been directed to their experimental studies on 3D behavior, seismic performance, load capacities, collapse mechanisms, and crack propagations. Previous studies indicate that most of the time the first period of the structure is torsion due to construction techniques outer faces is open to take the tunnel forms to out by cranes. This will cause less torsional rigidity, whereas for strong earthquakes, torsional rigidity has to be increased. Four different strengthening techniques, i.e., steel braces, reinforced concrete (RC) infill shear wall, precast concrete shear wall, and RC shear wall at the facade, were applied to improve torsion rigidity. Experimental studies and 3D nonlinear finite element analysis (FEA) were performed on models. The analytical model results, the economy and applicability of construction techniques suggest that steel bracing is the most suitable and practical method to improve torsional rigidity as well as seismic performance. Three-story scaled existing and strengthened experimental models are tested under pushover loads, and the results are compared with 3D nonlinear finite element analysis.