1. ABSTRACT A study for strengthened hinged frames subjected to four-point bending is presented in this paper. Four full scale hinged frames are tested in this study; three of them are strengthened using steel plates at locations of sagging and hogging moments. Epoxy mortar is used to bind the steel plates to the frames in positive and negative moments' areas. As part of the experimental scheme, clamps are used in addition to epoxy mortar in the fourth specimen to avoid steel plates separation. A non-linear analysis for the tested hinged frames using the software package ANSYS is also presented. The strengthened specimens achieved considerable improvement by increasing both; failure load and ductility, especially in the fourth specimen where clamps are used. Also for the purpose of assessment of other strengthening techniques, the results are compared with experimental results of a recent research carried by the author where the frames were strengthened using CFRP sheets.