In this work, analytical pushover curves for concentric braced steel frames with active tension diagonal bracings (X-CBF) are proposed. A pushover "spindle", characterized by two trilinear analytical capacity curves defined for an X-CBF system subjected to prefixed lateral forces distribution, is defined. The curves are able to grasp the elasto-plastic behavior of the X-CBFs. The reliability of this analytical proposal is verified by a series of numerical comparisons obtained through an accurate finite element model, calibrated on the basis of experimental results. The proposal is extended to whole single- and multi-storey structures, showing a good correspondence with the numerical results of the analyzed case studies.
