Seismic Performance Research Of High-Rise Building Structure With Irregular Plane And Weakly Connected Floor

In recent years,cross-shaped,Y-shaped and other plane concave and irregular buildings have appeared in Guangdong and Hong Kong.This kind of building,usually consisting of a central area and the limb structures extending in different directions,is connected by the floor.The separate limbs are independent of each other,thus creating better ventilation and lighting conditions.However,the width of the floor at the connection part is often small,forming a weakly connected floor.The structure with irregular planes and weakly connected floors is not recommended from the seismic concept,its seismic performance and failure mechanism have not been fully studied,and the seismic safety has not been fully demonstrated.The current code gives the seismic design concept and structural measures of this type of building,but it does not explain the calculation method of its seismic effect.The calculation method of the internal force of the connecting floor is not unified at present.Based on a series of typical irregular structures with weakly connected floors,this article discusses the analysis and design methods of weakly connected floor structures,and studies their seismic performance and failure mechanism.The main research contents are as follows:（1）Determine the appropriate analysis software and element of the floor,and analyze the simulation error.The differences of the floor elements in four commonly used structural design softwares were compared,and the analysis of test examples,element examples and specific structural examples were carried out.The results show that the ETABS shell element can better simulate the force of the floor,and the maximum error between calculation and test is less than 25%,and the average error is less than 10%.（2）Discuss the elastic analysis method suitable for weakly connected floor structures in small earthquake,and explore the distribution law of shear force of connecting floor along the height and the influence of different parameters on the stress of connecting floor.Taking the length-to-width ratio of the split limbs,the width ratio of the connecting floor to the typical floor of the split limbs,the thickness of the connecting floor and the layout of the split limbs as variable parameters,11 typical structures with weakly connected floors were designed.The elastic analysis was carried out by ETABS software.The results show that the structure with weakly connected floor should be calculated by elastic floor,and the time history analysis should be supplemented.Under the action of horizontal earthquake,the shear force of the connection floor increases gradually along the height of the structure,and the top floor of the structure reaches the maximum.The stress of the connecting floor is greatly affected by the length-to-width ratio of the split limbs,the width ratio of the connecting floor to the typical floor and the thickness of the connecting plate,but less affected by the layout of the split limbs.（3）The seismic design method of connecting plate is put forward and verified by elastic-plastic analysis in rare earthquake.Based on the internal force analysis results of ETABS in small earthquake and the amplification factor of moderate and rare earthquake,the seismic design method of connecting floor was proposed.Eleven typical models and one engineering case were analyzed by using SAUSAGE software,and the performance law of weakly connected floor structure was obtained in rare earthquake.The influence of different changing parameters on the seismic performance of the structure was analyzed,and it was proved that the connecting floor designed by this method can reach the preset performance target.（4）Reveal the failure mechanism of the structures with weakly connected floor.Taking one of the typical structural models as an example,the elastoplastic time history analysis under the action of a rare earthquake was carried out,and the performance law of the structure with weakly connected floor and each member was obtained,and based on the inter-story drift ratio criterion and the first vertical component failure criterion,the performance state of each member during structural failure was judged,and the failure degree,failure location,failure sequence and collapse mechanism of the structure were revealed.