In order to analyze the properties of horizontal resistance of RC columns

the total strain membrane effect theory of the RC beam was improved to found a theoretical method.The equation on the axial load and sectional neutral axis was found through the cross-sectional relationship and equilibrium relationship.The horizontal resistance equation was presented on the basis of virtual work principle

geometric relationship and equation on axial load and sectional neutral axis

which takes the axial gravity load and boundary restraint of RC column into account.A new theory and analytic formula was derived to calculate the relationship between horizontal resistance and deformation of RC column.The theoretical results were compared with the FEM analysis.The results revealed that the approach could calculate the horizontal resistance-deformation relationship of RC columns quantitatively

which was validated by the good agreement with the numerical results.The proposed theory has laid a foundation for further anti-blast dynamic analysis of RC columns subjected to blast loads.