Engineering Application Research On Three-line Defense Seismic Fortification Design Method For First Seismic Grade Frame With PSRC Vierendeel Truss Transfer Storey

Modern commercial complex buildings often need large bottom space structures with vertical functional zones.The vierendeel truss transfer storey of Prestressed Steel Reinforced Concrete(PSRC)is an ideal structure form.Based on the two-dimensional plane model test and finite element analysis,our team had put forward design method of first grade seismic three-lines of defense in PSRC vierendeel truss transfer storey frame structure,which has made a stipulated rule on domestic standard.Based on the three-line design method,this paper takes the three-dimensional spatial structure model as the research object,and carries out research on the engineering application of this kind of structure,which is of great significance to promote its popularization.Taking 8 degrees(0.2g)level of seismic fortification zone first seismic grade frame with PSRC vierendeel truss transfer storey as the research object,based on the design method of three-lines of defence,this paper design six basic examples with domestic mainstream structure design software ETABS,include the factors of different floors of lifting frames,global or local transfer storey,different lifting frame column net spacing and different large span number at the bottom.And we also design another four typical examples,like adding a little shear walls,core cylinder,high-position transfer storey and large chassis uplift single tower form.By comparing with Open Sees refined finite element spatial model,the effectiveness of SAUSAGE spatial model is verified.Based on the simulation analysis results of SAUSAGE model,the seismic performance of the above engineering examples is evaluated.Through the research of this paper,the main conclusions are as follows:(1)SAUSAGE model transfer storey and the following floor displacement angle,column end,and chord beam plastic hinge distribution location can envelope Open Sees model,reflecting that the analysis results are overall safe.SAUSAGE software is adopted to the seismic performance analysis in rare severe earthquake situation.This paper found that the quantitative control index checking of rotational capacity demand ratio is not necessary when the transfer column is not more than a slight damage and the upper frame column next to it is not more than a slighter damage.(2)The 6 basic engineering examples in this paper have considered the changes of many factors,such as floors of lifting frames,global or local transfer storey,lifting frame column net spacing,and the number of large span at the bottom.In the rare earthquake,the large span direction uplift frame column spacing decreasing results in the decrease of the beam and column’s ratio of plastic hinge,and there is no obvious difference in the seismic performance of other examples.This structure has achieved the three lines of defence fortification goal,reached its quantitative control index,and whole structural seismic performance can reach C performance goals.(3)In this paper,there are two methods to improve the lateral stiffness ratio of the structure and mitigate sudden stiffness changes along the floor height,by adding a small amount of shear walls in the transfer storey and its lower floors,and a core tube through each floor in the elevator of the building.The frame part should be designed according to the shear wall and cylinder body can work independently after withdrawal.Under rare earthquake,in the first line of defense,the beam and column hinge rate decreases and ratio of beam and column hinge rate increases,and the energy dissipation performance of the structure is obviously improved.At the same time,the number of plastic hinges of the transfer column is obviously reduced,and the seismic performance of the transfer storey is obviously improved.The seismic performance of the frame part of the structure can still meet the design requirements after the shear wall or core cylinder part is seriously damaged.(4)When the high-position transfer storey is set,the displacement angle between the floors next to the transfer storey increases significantly,which becomes the lower mutation point.When the bottom large chassis is used to lift the tower,the inter-story displacement angle of the first line of defense increases significantly.Under rare earthquakes,the damage degree of the beam components in the first line of defense of the two structures is aggravated,where the latter even reaches the severe damage,and the column plastic rate of the upper floor adjacent to the vierendeel truss is also significantly increased.However,the seismic performance of the calculation examples of the two structures can still meet the design requirements.