The Effect of Rocking Component of Strong Ground Motion on the Structural Response

Gholam Reza Nouri

In traditional earthquake engineering, structures are designed to resist only simplified representation of strong ground motion, in terms of three translational components of ground motion. The rotational components are almost ignored in design or assessment of engineering structures due to lack of recorded motions. Rotational component of seismic strong motion is attracting attention because of its influence on the overall response of structures. The previous studies were indicated that the effect of rocking component can be considerable especially in near field earthquakes. In this paper the effect of rocking component on the structural response is studied. The structures are modelled as single degree of freedom (SDOF) oscillator with varying structural parameters such as height and ductility. The data of Chiba dense array and geodetic method are employed to estimate the rocking ground motion from translational component. Elastic and inelastic analyses are performed on the models for two excitation cases: (1) rocking and translational components acting simultaneously and (2) only translational component. Comparing the dynamic response of the system for these two loading cases will be introduced as the effect of rocking component. The results show that, the response of structures was increased by including the rocking excitation. This influence is more considerable in tall and ductile structures.