Seismic Performance Analysis Of High-rise Building Structure With Steel Reinforced Beam Transformation Layer

A big chassis towers with a steel reinforced beam transformation layer is of complex body, and it is considered as multiple transfinite high-rise building structure. In order to maintain the safety and good seismic performance of the structure, research on the seismic performance of the structure is taken out in this paper.Firstly, a simplified model of the structure is established based on piece-wise continuity method. The analysis of the transformation layer height variation on the effect of the structure under horizontal action,which to suggest a preliminary scheme of reasonable transformation layer height position for the engineering design, is taken out by solving the vibration equation in MAPLE. Then accurate finite element analysis model of the structure is established respectively by the two commonly used software PKPM and MIDAS. Considering the bidirectional earthquake action, the vibration mode decomposition response spectrum method is adopted for elastic calculation analyzing the rationality and feasibility of design scheme of the structure under the action of minor earthquakes. On the basis of the analytical method, further comparison and analysis of transformation layer height position for the more comprehensive, reasonable and feasible scheme is taken to determine the final transformation layer height. And the structure supplement calculation with an artificial seismic wave and two natural earthquake waves is taken to validate the rationality of structure seismic performance indicators.Secondly, based on MIDAS software, within the elastic range, conversion component model with three type of cell is set up respectively, to calculate internal force of conversion components with different types of cell and study the influence of calculation of the internal force of conversion components with different types of cell, for subsequent analysis to provide basis for the selection of the cell of conversion components. With three typical transfer beam as analysis object, stem cell is chosen to establish finite element analysis model, to analyze the influence of internal force of conversion beam with different span ratio, for the optimization analysis of the transfer beam with reasonable span ratio.And then, using the dynamic elastic-plastic time history analysis method, based on Takeda three linear regression models, the elastic-plastic performance of whole structure under severe earthquake is studying out.Finally, the research of seismic performance of the structure under severe earthquake with the static elastic-plastic method (Pushover) is taken out. Based on capacity spectrum method of displacement control, select FEMA skeleton curve and the modal load form side force are select to the performance point of the structure. The analysis of the seismic performance of the whole structure and the development of plastic hinge in structure components is carry out, aiming at put forward the measures for strengthening the weak part of the structure.Study shows that the structure has good seismic performance, and the main conclusions following:1. In the optimization of structure plan, the inter-layer displacement Angle of changing law is almost the same, no matter by analytical method or finite element method. Applied to the optimization analysis of the preliminary plan of large chassis towers structure with transformation layer, the analytic method of piece-wise continuity with simplified model is feasible and has good practicability.2. Under the action of small earthquakes in two-way, the maximum inter-layer displacement angle of large chassis structure of two towers with conversion layer usually appear in the layer of the tower which above the transformation layer, also in the the central location of whole structure. But under strong earthquakes, inter-layer displacement angle of the transfer layer become biggest with the result of the internal force redistribution made by the stiffness mutation itself, as the transformation layer become weak layer.3. In asymmetric two towers structure of large chassis with conversion layer, the greater lateral stiffness of the tower, the smaller of its maximum inter-layer displacement angle and the lower height of the position of the maximum inter-layer displacement angle appear will be, But the maximum inter-layer displacement angle increase ratio with increasing of the height of conversion layer will be larger.4. There is few significant influence on seismic response of the structure as a whole by changing the span ratio of transfer beam, but a great influence on the internal force of transfer beam itself. In practical engineering, Optimization of span ratio parameters of transfer beam can be taken out by the analysis of a variety of schemes with different beam span ratio, based on the indicators of internal force of the transfer beam span ratio.5. In the final structure scheme after optimization, every indicators of seismic performance in the elastic-plastic analysis is within the limit stipulated. The energy dissipation mechanism of the whole structure is reasonable, meet the seismic design philosophy "strong column weak beam, strong shear weak bending". In view of the structure with weak link layer formed by transfer layer, strengthen layer of shear wall above the transfer layer and the top layer of the tower, suggest to adjust the structure stiffness to resist lateral force, improve the conjoined structure layout of the chassis and improve the structure intensity of the weak layer. Increase the strength of the weak layer, by taking appropriately reinforcement ratio and stirrup ratio and improving construction measures of the ductility of the components.