| As the main lateral resistance component of the frame-core wall structure and the first defense line of the structure,the performance of the core wall directly reflects the seismic performance of the structure.Hence,it is of great significance to fully study the mechanical behavior of the core wall to master the seismic capability of the structure.However,at present,the research mainly focuses on the core wall in square plane form,lacking of the research on other plane form.The z-shaped buildings have the advantages of north-south transparency,good lighting,etc,which is quite popular in the south China.In order to meet the requirements of building fire protection,its core cylinder plane is also z-shaped.It is meaningful for the popularization and application of z-shaped buildings and structural design to research deeply on the seismic performance of the core wall in the plane form of z.Therefore,based on the actural engineering of a z-shaped building in Shenzhen,analysis on the core wall in the plane form of z was carried out through static elastoplastic analysis,incremental dynamic analysis(IDA)and seismic vulnerability analysis:(1)In order to study the seismic performance of the z-shaped core wall in all bulges ratio on different load Angle,five core wall in plane form z with different protruding proportions have designed.Through the static elastoplastic analysis along 12 load angles in the software PERFORM-3D,the major axis,the minor axis and the range of adverse load was confirmed.It shows that the minor axis of z-shaped core wall is in the zero degree direction,which is independent of the bulge ratio.The major axis of the z-shaped core wall with the bulge ratio between 0 and 1/9 and 1/4 and 1/3,including 1/9 and 1/3,is in the 60 degree direction.The major axis of the one with the bulge ratio between 1/9 and 1/4,including 1/4,is in the 105 degree direction.The seismic performance of the z-shaped core wall is worse in the certain range of load angle which relate to its bulge ratio.(2)Aims to explore the influence rule of the beam-span height ratio of couple beams in X direction and Y direction on it,the z-shaped core wall in different bulge ratio was loaded along the directions of 0 degree and 90 degree respectively.Through the comparison of the seismic performance,the recommended value was given.The results show that the beams-span height ratio of the coupling beams parallel to the load angle has great impact on the performance of the z-shaped core wall.As the beams-span height ratio decreases,he ultimate bearing capacity of the core wall is obviously improved,but the ductility decreases.However,the beams-span height ratio of the coupling beams perpendicular to the load angle are no effect on the performance of the z-shaped core wall.There is transverse shearing perpendicular to lengthwise direction of the beam.It is suggested that the beam-span height ratio of the Y-direction coupling beams should be between 1.3 and 2.0 and the one of the X-direction coupling beams of the z-shaped core wall in bulge ratio from 1/4 to 1/3,1/5 to 1/4,1/6 to 1/5 and 0 to 1/6 should respectively take between 1.0 and 2.0,1.3 and 1.5,1.5 and 2.0,and 2.0.(3)In order to study the dynamic performance of the z-shaped core wall,IDA analysis and vulnerability analysis were performed on the z-shaped core wall using 22 seismic records recommended by ATC-63.Taking the maximum peak acceleration of ground motion(PGA)as IM parameter and the maximum inter-layer displacement Angle(?)as DM parameter,amplitude modulation was carried out for many times,and its IDA curve cluster,IDA Quantile curve and vulnerability curve were obtained respectively.The results show that the dispersion of the IDA curve clusters taking ?-PGA as the DM-IM parameter is small.The stiffness degradation degree of the z-shaped core wall with protruding ratio in the range between 0 and 1/4,including 1/4,is similar,and its collapse failure probability under the action of 8-degree(0.3g)earthquake is less than 20%.However,The Z-shaped core wall with protruding ratio in the range between 1/4 and 1/3,including 1/3,has the fastest stiffness degradation under the action of ground motion,and its collapse failure probability under the action of 8-degree(0.3g)earthquake is as high as 92%.(4)The performance in static and dynamic analysis of the z-shaped core wall is roughly the same.The z-shaped core wall with protruding ratio in the interval between 1/4 and 1/3,including 1/3,has the high probability of collapse because its torsion effect is large and the connecting beam on the bottom is easy to be damaged.The z-shaped core wall with protruding ratio in the interval between 1/9 and 1/4,including 1/4,has poor ductility,and its stiffness degenerates rapidly,but its collapse probability is relatively low.The z-shaped core wall with protruding ratio in the interval between 0 and 1/9,including 1/9,has better ultimate bearing capacity and ductility,and the lowest collapse probability.Through ETABS,a kind of structural analysis software,the elastic time history analysis of the damping structure under the action of frequent earthquakes is done,which show that the self-resilient coupling beam damper can effectively reduce the torsion effect of the structure and enhance the ductility of the structure.(5)The design suggestion of the z-shaped core wall was given through the study.It is suggested that the z-shaped core wall with protruding ratio in the interval between 0 and 1/9,including 1/9,should be preferred and design as the usual structure.As for the z-shaped core wall with protruding ratio in the interval between 1/9 and 1/4,including 1/4,a smaller beams-span height ratio of the coupling beams should be used.The z-shaped core wall with protruding ratio in the interval between 1/4 and 1/3,including 1/3,should use the energy dissipation and damping devices,such as the self-resilient coupling beam damper,to improve the seismic performance and reduce the probability of collapse failure. |
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