Study On The Structure Mechanical Property Of Frame Structure,Raft Foundation-Foundation Work Together

Frame structure with clear force, the good overall stiffness, fast construction speed, is widely used in modern architecture. Most designers assume that the foundation is completely rigid in the seismic design, regardless of the cooperative work of the foundation and upper structure. It leads to the big difference of the theoretical value and actual value.Therefore,when framework structure, raft foundation and foundation work together, the performance of stress study on the structure is very necessary.This article uses the finite element software ANSYS to establish two kinds of three-dimensional finite element model,which consider no cooperative work and cooperative work. The foundation selects entity unit,the raft and floor use shell element, the beam-column choose three-dimensional beam element, the contact between the foundation and the raft uses the contact element. This paper respectively analyses the overall structure stress under static and seismic, especially under teamwork,changing the raft foundation thickness and the foundation elastic modulu.The results showed that:(1) Under the action of static, after cooperative work, the maximum settlement of structural system increases by 7.561mm; In the underlying framework,the bending moment and shear force of the corner column respectively decrease by 66.54 KN.m and 75.98KN;the beam bending moment and shear force don't vary obviously;(2) Under the seismic action, after considering working together, with the increase of modal order,the structural vibration of natural frequency and period gradually increase.In the eighth order,modal natural frequency decreases by 10.6%, cycle increases by 11.87%;In the underlying framework,the bending moment and shear force of the corner column respectively decrease by 33.16 %and 43.44%;(3) Under the seismic action, after considering working together, raft thickness increases100 ?,foundation settlement decreases 7% ~ 8% and shear decreases 9.22%, the underlying beam-column moment decreases about 1%;The foundation elastic modulus increases 10 mpa,foundation settlement decreases about 4%, the internal forces influence of the foundation elastic modulus on the frame column is greater than frame beam.Thus, cooperative work had a greater influence on the displacement and internal force of structure, engineering designers in the design of building structures should consider teamwork on the influence of the structure.