A vibration damper device for warehouses and similar buildings of the type comprising at least one substantially horizontal main beam, and at least one substantially horizontal covering crossbeam which has an axial end in abutment on said main beam and extends transversely to the main beam; the vibration damper device being characterized by comprising: - a first anchoring structure which is adapted to be rigidly fixed on the body of the main beam, at or close to the axial end of the covering crossbeam; - a second anchoring structure which is adapted to be rigidly fixed on the body of the covering crossbeam, at or close to the axial end of the crossbeam; - an intermediate floating element which is slidingly coupled to the first anchoring structure so as to move freely forward and backward with respect to said first anchoring structure in a first direction (d 1) locally substantially parallel to the longitudinal axis of the main beam, and is also slidingly coupled to the second anchoring structure so as to move freely forward and backward with respect to the second anchoring structure in a second direction (d 2) locally substantially parallel to the longitudinal axis of the covering crossbeam; - a first deformable connecting member with elastoplastic behaviour, which is interposed between the first anchoring structure and the intermediate floating element, and is structured so as to deform in elastoplastic manner during movement of the intermediate floating element with respect to the first anchoring structure in said first direction (di); and - a second deformable connecting member with elastoplastic behaviour, which is interposed between the second anchoring structure and the intermediate floating element, and is structured so as to deform in elastoplastic manner during movement of the intermediate floating element with respect to the second anchoring structure in said second direction (d 2). - a first anchoring structure which is adapted to be rigidly fixed on the body of the main beam, at or close to the axial end of the covering crossbeam; - a second anchoring structure which is adapted to be rigidly fixed on the body of the covering crossbeam, at or close to the axial end of the crossbeam; - an intermediate floating element which is slidingly coupled to the first anchoring structure so as to move freely forward and backward with respect to said first anchoring structure in a first direction (d 1) locally substantially parallel to the longitudinal axis of the main beam, and is also slidingly coupled to the second anchoring structure so as to move freely forward and backward with respect to the second anchoring structure in a second direction (d 2) locally substantially parallel to the longitudinal axis of the covering crossbeam; - a first deformable connecting member with elastoplastic behaviour, which is interposed between the first anchoring structure and the intermediate floating element, and is structured so as to deform in elastoplastic manner during movement of the intermediate floating element with respect to the first anchoring structure in said first direction (di); and - a second deformable connecting member with elastoplastic behaviour, which is interposed between the second anchoring structure and the intermediate floating element, and is structured so as to deform in elastoplastic manner during movement of the intermediate floating element with respect to the second anchoring structure in said second direction (d 2).