New expression to estimate out-of-plane displacement of special concentrically-braced frames

Induced non-structural damages due to strong ground motion can affect the performance levels of a building. Special concentrically-braced frames are used in high and moderate seismicity regions because of high ductility and energy absorption capacity. In special concentrically-braced frames, storey drift ratio and the out-of-plane displacement are the most important parameters defining structural and non-structural damage. Various expressions for out-of-plane displacement without inertial effects are available in the literature. This study describes the development of new expressions to determine out-of-plane displacement for special concentrically-braced frames based on the seismic response of 16 different single-storey models: eight inverted-V and eight X-braced frames. Initially, out-of-plane displacement is calculated based on cyclic loading and then modified for earthquake excitations. A simplified iterative procedure is proposed to calibrate out-of-plane displacement expression using revised effective mass. Two new expressions for determining out-of-plane displacement are developed as a function of storey drift ratio, slenderness ratio, and the ratio of the tension to compression strength.