Application Of The Method Of Response Surface FEM Apply In Reliability Analysis Of Existing Concrete Bridge

Because of structural damage, material aging,the carrying capacity of bridges reduces gradually. Therefore how to evaluate the existing bridges effectively and calculate their reliability has become a world subject in bridge engineering academia. The aging of concrete, to the mechanical performance falling of existing reinforced concrete bridges, is a important facet. Adopting reasonable concrete constitutive equations is the base of analyzing reinforced concrete bridges. On the basis of experiment, this thesis studies the stress-strain curve of ageing concrete in the state of single axle compression. The curve indicates that the ageing concrete shows obvious nonlinear character at the beginning of compression, and brings obvious deformation under the action of small stress. The curve also indicates that the peak value of the ageing concrete strength and elastic module is declined, and the curve shape becomes sharp. This thesis calculates the ultimate carrying capacity, deflection, stress and strain of the experimental beam, By using large-scale finite element programming ANSYS, putting the engineering background on experimental simply-supported reinforced concrete beam, and considering material nonlinear adopting three-dimensional entity model. And the results of numerical simulation indicate that the failure of the experimental beam occurs at midspan in form of compression, which is consistent with experiment phenomenon. Thereforce, the model of this thesis is correct and reliable. A practical reliability algorithm is put forward, i.e, the method of response surface FEM base on ANSYS. Through the curve of cumulative distribution, it calculates the flexibility reliability of experimental beam in serviceability limit state, under the action of different load. The calculation is completed by repetitional iteration. And on the base of reliability analysis, the parameter sensibility anslysis of experimental beam is carried out. The results indicate that in the factor of flexibility reliability of experimental beam, the effect of the reinforced elastic module is dramatic, the beam high and the area of main reinforced is also grate, but the thickness of top plate and concrete protective layer are less.