Low cost passive dampers for highway traffic signs

A low cost passive mass-rubber damper is introduced in this work to mitigate damage of highway signs caused by ground motion and wind gusting. The damper is designed and constructed to alleviate stresses due to bending, shear, and fatigue loading. Lab experiments based on sign responses and strains were conducted in order to evaluate the damper effectiveness in extending the life of the sign structure. Experimental Modal Analysis was performed to deduce the modal parameters of the structure using Easy Analyst and ME'scope commercial software. Ground motion was simulated using a shaker table and lighten earthquake signals. The wind gusting is simulated by simply pulling the tip of the sign and then releasing it. The results have shown that the proposed damper was able to minimize the horizontal relative ground motion between the base of the structure and the ground, which is an indication of smaller shear forces. Strain results have shown that the proposed damper was able to lower the maximum strain by up 73 percent. Finally, the damper was very effective in filtering the high frequency components of the signals entering the system, minimizing by that failure due to high cycle fatigue.