Research On The Multi-scale Mechanical Performances Of SRHSC Frame Structure

Taking the advantages of high rigidity, high bearing capacity and superior seismicperformance into consideration, SRC composite structures would be the first choice to beapplied to the high-rise, long-span, heavy-load and towering structures in high intensitysecurity areas. Using of high-strength concrete in SRC composite structures which makestwo materials a better team work meets the development trend of structures in the verticaldirection and the horizontal direction, and then the excellent structural performance andgood economic benefits will be facilitated. However, with the limitation andnon-applicability of original theories and the fact that the global giant earthquakes occurfrequently, it is necessary to evaluate the multi-scale mechanical properties and analyzethe loss expectation of earthquake damage of SRHSC frame structure.Numerical simulation combines with physical model test and theoretical analysisare adopted to study the multi-scale mechanical performances and earthquake damageloss expectation of SRHSC frame structure. The key mechanical problems in thecomponent scale and seismic damage evolution laws in various scales are discussed inthis paper, then the damage model in macroscopic scale are established and earthquakedamage loss expectation of individual buildings are achieved finally. The main researchworks and conclusions are shown as follows:1. Based on mechanical behavior experiment of19steel reinforced high-strengthconcrete (SRHSC) beams, the crack development mode and failure mode are observed,and main factors which affect the mechanical behavior of SRHSC beam are revealed,then the relationships between concrete strength, steel ratio, shear span ratio, loadingmode, shear connection mode and flange width ratio (ratio of steel flange width andbeam width) are obtained. Methods for calculating the shear force of interface betweensteel and concrete under different shear connection modes are proposed, and theformulas for calculating beams bending stiffness in the short-term load effect are putforward. The calculting model and formulas applied for SRHSC beam bearing capacityof the flexural strength and the shear strength are established finally.2. Based on seismic performance experiment of16SRHSC columns, the crack development mode and failure mode are observed, and mechanism of the typical failuremodes is analyzed in this paper. Main factors which affect the seismic performance ofSRHSC column are studied, and then the influence laws of concrete strength, shear spanratio, axial compression ratio and the volumetric stirrup ratio on column seismicperformance (such as material strain distribution, the restoring force characteristics, thedeformation capacity and the hysteretic energy capacity) are revealed.3. Taking the calculation accuracy and the calculation cost into consideration, thenumerical modeling theorys for component scale with ABAQUS program and forstructure scale with OpenSees program are put forward respectively. The ralatedresearch works contain the selection of the material constitutive model and units, therealization of the bond-slip between the embedded steel and concrete in the numericalmodeling, the technical means of adding new materials and new unit types, thereliability verification of the modeling theory and so on.4. Seismic damage calculating models for component and storey are established byusing the typical mechanical performance indexs, and the damage sensitivity analysesfor main factors of component and storey are conducted by numerical simulation andexperimental research, then the damage evolution laws between closely scales arerevealed and the influence of beam equivalent flange width, column axial compressionratio and other performance parameters on storey damage are explored. The storeydamage model of SRHSC frame structure under cyclic loads is established ultimately.5. According to calculating formulas for column yield rotation and ultimate rotation,and taking the calculating method for interlayer maximum displacement angle intoaccount, the judging criterion for SRHSC frame structure damage model is built. Thedamage evaluation function which regards natural period frequency rate and maximumdisplacement on the top of the structure as characteristic variable is establishedrespectively, and the prescribed damage method is adopted to reveal the influence lawsof ground motion intensity, seismic wave attributes and structure height width ratio onwhole structure damage. Taking full consideration of influence of location, quantity andinjury degree of the damage storey on structure mechanical properties, method fordetermining the floor damage weights coefficient is proposed, and the seismic damagemodel for SRHSC structure is finally established.6. The recommended formulas for calculating the exceeding probability ofspecified intensity under different fortification intensities are proposed and the seismichazard curves of construction sites under different fortification intensities are presented,then the regression formula reflecting the relationship between interlayer maximumdisplacement angle and inputting ground motion intensity is established. Influence lawsof inputting ground motion intensity on the maximum interlayer displacement angle of SRHSC frame structure under different fortification intensities is revealed, and thefailure probabilities of structures with specified fortification intensities which subjectedto different damage degree is obtained. Taking the direct economic loss, indirecteconomic loss and the casualty loss into consideration, the earthquake damage loss ofthe individual buildings is fulfilled. The earthquake damage loss expectation of theindividual SRHSC frame structure achieved finally.