Study On Nonlinear Earthquake Response Of Rigid Rocking Body

Earthquake response research based on the design concept of bearing capacity has been very mature,but with the frequent occurrence of strong earthquakes in the world in the past 20 years,researchers have found that the traditional concept has limitations.Under the action of a large earthquake,the structure cannot possibly exhibit non-linear behaviors such as plastic hinges and basic mat uplift.Therefore,some scholars have proposed the theory of “rocking vibration isolation”.Different from the traditional method,the concept of oscillating isolation is no longer overstrengthening the structural members to avoid the nonlinear behavior of the structure under large earthquakes,allowing the structure to oscillate,the basic lift,the plastic hinge,and the plastic deformation of the foundation soil.,And make full use of these nonlinearities to consume the energy of the earthquake and reduce the impact of seismic loads on the superstructure.This concept has been recognized,valued and researched by more and more scholars.The influence of the basic lift on the seismic response of structures has become a hot spot in seismic research.In this paper,five types of tests,fixed rigid body,non-sliding rigid rocking body,rigid-slide rocking body,rigid rock-rock column,and sand-rock rigid rocking body,are designed first,and different types and amplitudes of seismic loads are applied.Analysing the test results,the basic law of the seismic response of the rocking structure was initially explored.Secondly,through comparative analysis,the effects of seismic load type and amplitude,basic mat uplift,slip and ground soil properties on the horizontal and vertical dynamic response of the specimen are discussed.The specific comparison is: fixed rigid column and no-slip Rigid rocking column test,non-sliding rigid rocking column and sliding rigid rocking column test,sliding rigid rocking column and rigid rocking column test on flexible foundation,soft soil foundation and sandy soil foundation test,etc.In this paper,after a series of experiments and numerical simulation analysis,the basic mat uplift,slip and the characteristics of ground soil properties influence the seismic response of the rocking structure.Mainly reflected in the following aspects:(1)under the action of small and medium earthquakes,the basic mat uplift and slip will reduce the dynamic response of the upper structure of the rocking structure system.(2)When large earthquakes are encountered and the basic mat uplift and slip occur,the structural dynamic response will obviously increase,but the vertical dynamic response at the top of the structure will decrease when slip occurs.(3)The flexible foundation can reduce the dynamic response of the structure,in which the sandy soil foundation has a greater impact on the horizontal dynamic response,while the soft soil foundation has a greater impact on the vertical dynamic response.Finally,on the basis of experimental research,the contact element method was used to simulate the test,and a calculation method considering the influence of the uplift and slip of the foundation was established.The comparison test and numerical simulation results verify the feasibility of the calculation method.On this basis,the law of seismic response of the rocking structure is discussed.According to the comparison between the numerical simulation results and the experimental data,the contact surface element method can simulate the non-linear characteristics of the contact surface to a certain extent,but it can not consider the impact effect during contact,and can be initially applied to the seismic response analysis of the rocking body.