Study On Structural Response Of Ground Shaking Torsional Components To Different Aspect Ratios

The existing codes in China only take into account the influence of the ground motion component in the design of structures,but many seismic hazard phenomena show that there are three rotational components in addition to the three translational components,and the influence on the structure cannot be ignored,so the influence of the structure under the action of the rotational component needs to be further studied.This paper introduces the current status of research on the rotational components and the theoretical synthesis methods at home and abroad,and adopts the frequency domain method to obtain the angular acceleration time course of the rotational components of ground shaking.Shake table tests of seismic and isolated structures under multi-dimensional ground shaking were carried out,and the comparison of floor acceleration and floor displacement response was carried out by the finite element software ABAQUS to verify the reliability of the structural modelling method and the rotation component input method in the software.On this basis,steel frame structure models with aspect ratios of 1,2 and 3 were established,and 10 velocity pulses with and 10 velocity pulses without near fault were selected of seismic waves,the dynamic response analysis of the seismic and seismically isolated structural models with three aspect ratios is carried out,and the main conclusions are as follows:(1)As the aspect ratio increases,the first fourth-order period of the seismic-resistant and seismically isolated structures increases,as does the period ratio,and the structural torsional effect is enhanced;(2)For both structural models,the structural response with velocity pulse near-fault ground shaking is greater than that without velocity pulse.The torsional component of the ground shaking alone triggers the structural dynamic response,and the structural response increases further when the flat and torsional components of the ground shaking act together.The torsional component of ground shaking is the main source of torsional angle and torque between the layers of the symmetrical non-eccentric structure,and the torsional effect increases further as the aspect ratio of the structure increases;(3)As the aspect ratio increases,the acceleration response of the structure at each storey generally tends to decrease,and the axial force,shear force and bending moment at the base of the column tends to increase.Among them,the internal forces of the corner and side columns at each storey are more influenced by the torsional component,while the influence of the middle column is smaller;(4)The seismic isolation effect under the action of the ground vibration translational component is better and increases with the increase of the aspect ratio,while the seismic isolation effect under the action of the ground vibration torsional component is the second best and decreases with the increase of the aspect ratio of the structure;(5)The inter-storey displacement angles of the structure under small and large earthquakes meet the code limits when only the torsional and translational components of earthquakes are considered to act alone.