Nonlinear dynamic and natural frequencies of a gabled frame with elastic restraints and semi-rigid connections are investigated by using a program in OpenSees software. Natural frequencies are obtained for two states, which are flexible connections and semi-rigid supports, separately. The mode shapes of structure are also obtained for the described states. Also, the effect of connection flexibility on the dynamic responses of the frame is obtained for different values of peak ground acceleration. The members of this structure are modeled as a nonlinear beam-column element. The members of structure are assumed to be prismatic. Two equal lumped masses at the head of two columns in horizontal and vertical directions are considered as the mass pattern of structure. Note that three degrees of freedom are allocated to all nodes. Furthermore, the mode shapes of frame are obtained. Conclusively, the effects of semi-rigid connections and supports on the natural frequencies and mode shapes of structure are investigated. As results, the top level displacement and base shear responses of frame are reported.

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