Research On Anti-seismic Performance Of Ground-Base-RC Frame Structure Under Near-field Earthquake

Near-field earthquake is one of the hottest issues in the anti-seismic engineering field. There are huge differences between near-field and far-field earthquake,including vertical effect, long cycle speed pulse, directional effect, which lead to its different impact on the anti-seismic performance of structure.Given the fact that reinforced concrete frame structure has been widely applied in the field of engineering, reinforced concrete frame structure is chosen as the research object in this thesis, the dynamic elastic-plastic time-history analysis is carried out and the near-field anti-seismic performance of structure under earthquake is explored. In addition, the structure is built in a particular site, the soil-foundation-the upper structure is consequentially bound to form an unity, structural anti-seismic performance is inevitably affected by the soil-structure interaction. Therefore, this thesis will be a study about anti-seismic performance of RC frame structure of soil-structure interaction under near-field earthquake. Specific studies are as follows:(1)First, the research background and significance of soil-structure interaction is briefly introduced in the thesis. Based on concise analysis of relevant research status and application, the thesis’ s research content and technical approach is presented.(2)After analyzing and contrasting different simulation methods, the method of ATC40 is chosen to simulate the soil-structure interaction. In order to analyze elastic-plastic time-history of structure seismic responses, SAP2000 is applied for modeling after ascertaining correlation parameters of time-history.( 3) Seismic simulation of a 10-floor reinforced concrete frame structure is conducted by the elastic-plastic time-history method under the analogue of a near-field earthquake: A seismic wave each in the II, III,IV type of field is selected to simulate the structure under 7 intensity of frequent and rare earthquakes. Take soil-structure interaction, second-order effects and seismic responses of rigid foundation into consideration, the displacement and the shear force of relative story of structure is contrasted and analyzed under the action of horizontal seismic wave and the joint action of horizontal and vertical seismic wave. It is plain to see in the result that vertical seismic action and soil-structure interaction effects should not be ignored,and as the soil becomes soft, adverse effects increase.( 4) To study the influence of vertical seismic wave on the anti-seismic performance of structure, seven seismic waves, whose vertical and horizontal PGA ratio is different respectively, are selected in the II,III,IV field. The time-history analysis of the structure is conducted based on the soil-structure interaction. The influence rule between maximum relative story displacement, top displacement,bottom shear force, vertical and horizontal PGA ratio of the structure under 7 intensity of frequent and rare earthquakes is found out. It show that under the near-field earthquake, and with soil-structure interaction, the anti-seismic performance of structure will be least affected while the ratio of vertical and horizontal PGA is around0.6, affected the most while the ratio is around 0.7.( 5) When the height of the reinforced concrete frame structure is changed,identical method is applied to conduct elastic-plastic time-history analysis on the structure. Comparing the parameters with those before, it is concluded that under near-field earthquakes, as the height of the structure increases, the enhancement coefficient of seismic response index becomes larger, the structure becomes less secure, moreover, while the field soil becomes softer, the seismic effect influence on higher structure becomes stronger.