| Because the advantages of special-shaped column structure of Steel Reinforced Concrete(SRC)are obvious compared to the same of Reinforced Concrete(RC)on bearing capacity,ductility performance,engineering techniques,etc.,researches and applications have been done to this new structure by domestic scholars.At present,domestic researches mainly concentrate on components such as special-shaped columns,joints of SRC frame with special-shaped columns,etc.Researches on overall the performance of frame structure have just started.Moreover,only the quasi-static test had been done to the plane frame of the special-shaped columns,theoretical supports for the seismic response rules and control measure studies are still insufficient.Therefore,in this paper,systematic researches have been done on the seismic response rules and control measure studies of the spatial frame structure with SRC special-shaped columns in the following four aspects.1 The Lateral,vertical and torsional dynamic characteristics of a 5-floor solid web spatial frame structure model of SRC special-shaped columns were acquired via the 3-dimensional seismic simulation shaking table test;in addition,a comprehensive analysis has been done to the multi-dimensional seismic responses of both the structure and components.The results show that: as the seismic intensity increases,the free vibration frequency of the frame structure of SRC special-shaped columns declines constantly,the acceleration amplification coefficient declines gradually,and the structural responses are mainly shear type;The corresponding vibration mode form of the first 5 orders of free vibration frequencies in turn were: X direction translation,Y direction lateral-torsional coupled,Z direction vibration,torsion,and Y direction translation;under the 3-dimensional seismic effect,because the axial stiffness of the model is relatively higher,and the vertical vibration response of the structure is relatively smaller,the impact of accidental eccentric torsion to the seismic performance of the structure of special-shaped columns not exceeding the height limitation is small.When the structure is symmetrically arranged,the SRC special-shaped columns can maintain the linear elastic torsion;under the effect of strong earthquake,the storey stiffness degenerates relatively faster,and the lateral displacement curve of the entire structure shows an “S”.In the later stage of the elastic-plastic stage,the plastic hinge firstly appears on the side frame beams,which conforms to the beam-column hinge mechanism,and shows that the structure is with a good seismic capacity and deformation performance;After the comparison between the simulated seismic responses and design values,it has been discovered that the bending moment caused by the horizontal displacement is the main aspect of those columns subjected to bending.The N-? second-order effect of SRC special-shaped columns is very small,and the vertical gravity load is the leading factor of those beams subjected to bending and shearing.2 Considering the influence of the torsion of the column member,the theoretical formulas for calculating the lateral stiffness,torsional stiffness,internal force and deformation of the special-shaped column are derived.The rotational components of ground motion and floor torsional stiffness considering the ground rotational components was approximately determined via the establishment of seismic response analysis model considering the ground rotational components;in addition,the lateral-torsional period ratio generated by the ground rotation has been introduced on the basis of the above,and the Y direction lateral-torsional coupled vibration characteristics of eccentric structures considering the impact of ground rotation were analyzed.The results show that: The trends of theoretical calculation of stiffness and internal force considering torsion of special-shaped column member agree well with experimental situation.The variation tendencies of free vibration frequency ratio,lateral-torsional coupled coefficient,torsionamplitude ratio,vibration model participation coefficient,and torsional effect ratio of eccentric structures considering the impact of ground rotation is the same as that of the structures only considering the impact of eccentricity;in addition,the above two have similar lateral-torsional coupled response rules.However,the ground rotation has an obvious amplification effect on the internal force and torsion deformation of the structure.3 Researches were done on the elastic-plastic torsion response rules of eccentric frame structures of SRC special-shaped columns designed according to standards using beam and column units of detailed fiber models based on the flexibility method.The results show that: Under the effect of strong earthquake,the inter-story drift ratio of the frame structure of SRC special-shaped columns is obviously affected by the floor location,eccentric distance and intensity of ground motion.In case the eccentricity is more than 0.3,then the lateral-torsional coupled effect of earthquake response of the structure is obvious;In case the eccentricity is not more than 0.1,and the structural ductility coefficient is 3.56,then the ductility is relatively good.The ductility coefficient declines constantly as the eccentric distance increases;and the decline amplitude declines constantly as the eccentric distance increases.From the capacity spectrum method,it shows that,the SRC special-shaped column structure with a larger eccentric distance reaches the performance point earlier,which is relatively disadvantageous in terms of structural seismic;Under the effect of strong earthquake,the weak floor of SRC specialshaped column structure with a small eccentric distance appears in the lower part of structure;and the same of SRC special-shaped column structure with a larger eccentric distance appears in the upper part of structure.4 Adopting strain-energy based two-parameter damage model to assess the damage degree of the frame structure of SRC special-shaped columns.In consideration of the section feature and mechanical property of SRC special-shaped column,torsion control indicators and measures are proposed to optimize and adjust the seismic design and calculation procedures of SRC frame structure with special-shaped column,to provide a reference for optimal seismic design and torsion-resistance design of SRC frame structure with special-shaped column.Through above researches,the seismic response analysis model of SRC frame structure with special-shaped column was explored and established,a set of seismic response rules of SRC spatial structure with special-shaped columns was summarized,and references were provided to the torsion-resistance and seismic design of SRC special-shaped column structures. |
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