In view of the defects of increase coefficient of bias distance \%\% formula (GBJ10-89)in practice,considering the result of the limitstate alternative method resulted from the effect of the second coracte moments,by regression analysis and after much calculalion,the regression count expression formula of increase coefficient of bias distance is established.

To be in light of the fault of increase coefficient of bias distance η formula in current lightweight aggregate concrete standard in practice,considering the influence of two stepped moments by using the entire proceeding analyses theory,we reached the η of corresponding side and side deflection f and curvature φ of circular cross section biasing structure whose column ends are different.

Taking into consideration the fact that all loads will not be woved in building construction when a structure is strengthened, we studied by the method of computer-test, how to calculate eccentricity amplifier of the slender concrete column strengthened non symmetrically with concrete to enlarge section subjected to axial load and bending moment.

Based on artificial neural network,this paper presents a new method of estimating the eccentricity magnification factor η of reinforced concrete columns.

Improvement of moment amplification factor method considering second-order effect in lateral sway frame;