Research On Seismic Ultimate Bearing Capacity Of Reinforced Concrete Structure Based On Strength Fusion

Reinforced concrete(RC)structures have the advantages of good moldability,good integrity and long service life,and are widely used in engineering structures.At the same time,reinforced concrete structures also have the characteristics of large self-weight,which are the factors must be considered in the analysis of seismic ultimate bearing capacity.At present,the ultimate bearing capacity analysis of reinforced concrete structures mainly includes fiber beam-column element method,incremental nonlinear finite element method and elastic modulus adjustment method,among which the elastic modulus adjustment method has higher calculation efficiency and stability,and has been successfully introduced into reinforced concrete structures,but there are still insufficient considerations for the influence of selfweight and other constant loads on the ultimate bearing capacity of the structure.Therefore,in this paper,an improved strength fusion method for the analysis of the ultimate bearing capacity of structures with significant constant load effect is studied,and it is introduced into reinforced concrete structures,and then combined with the seismic lateral force distribution,the linear elasticity iterative analysis format for the seismic lateral ultimate bearing capacity analysis of RC structures is studied,and the algorithm has better calculation accuracy and calculation efficiency through comparison.The main research contents are as follows:(1)By introducing the strength reduction factor,an improved strength fusion method for structural ultimate bearing capacity analysis with significant constant load effect was established.Firstly,the strength reduction factor is defined according to the generalized yield function,according to which the axial strength and bending strength of the components under the combination of multiple internal forces are corrected,and an improved strength fusion technology is established.Then,the homogeneous expression of the generalized yield function is established by regression analysis,and the element bearing ratio is defined accordingly.Furthermore,the stiffness damage of the structure during loading is simulated by strategically reducing the elastic modulus of the high load-bearing element,and the ultimate bearing capacity of the structure with significant constant load effect is quickly calculated through linear elastic iterative analysis.Finally,through the analysis of examples and the comparison with the calculation results of the Elastic-Plastic Incremental Analysis(EPIA),the wide applicability of the proposed method is verified,and the scope of application of the traditional strength fusion method is clarified.(2)An iterative analysis format for linear elasticity analysis of RC structure with significant constant load effect is established.Firstly,the strength reduction factor of RC structure is defined according to the generalized yield function of RC structure,and then according to the characteristics of reinforced concrete structure,the effects generated by the weight and external constant load of the structure itself and its ancillary structure are integrated into the cross-section strength through improved strength fusion technology,and a modified structural model is established.Then,based on the specification,the calculation formula of boundary axial force and boundary bending moment of reinforced concrete section after integration into constant load is derived.Then,the stiffness damage process of the structure is simulated by strategically reducing the elastic modulus of elements,and then the ultimate bearing capacity of RC structure with significant constant load effect is analyzed.The example analysis shows that the bearing capacity calculation results of the proposed method are more consistent with the experimental results and the results of the fiber beam-column element method,and have high calculation efficiency.(3)An iterative analysis format of linear elasticity for the analysis of seismic lateral bearing capacity of RC frame structure is proposed.Firstly,the lateral force distribution of the structure under seismic load is determined according to the characteristics of mass distribution and stiffness distribution of the structure,and then the effect of constant load on the structure is integrated into the cross-section strength through the cross-sectional strength fusion technology,and then the elastic modulus of the high load-bearing element is strategically reduced to simulate the structural stiffness damage process,and the collapse mode and ultimate bearing capacity of the RC frame structure under the action of seismic lateral force are determined.The example analysis shows that the ultimate bearing capacity calculation results of the improved intensity fusion method have high accuracy,and can effectively simulate the collapse mode of the structure under the action of seismic lateral force.