Modeling of magneto-rheological dampers to be used in semi-active control of civil engineering structures is addressed. The behavior of this kind of dampers is modeled through a first order Lugre dynamic friction model whose structure is analytically simpler than other dynamic friction models used in the literature. With this structure real-time parametric identification of the magneto-rheological damper is possible. Forces obtained with this modeling approach are in good agreement with those produced by other models.