This project will develop a novel Constrained Layer Damper (CLD) for retrofitting High-Mast Illumination Pole (HMIP) structures to mitigate wind-induced vibrations. Work in Stage 1 will focus on mechanical characterization of viscoelastic (VE) materials, and the subsequent numerical modeling and optimization of the CLD. A series of axial tests and shear relaxation tests will be performed to obtain the hyperelastic and viscoelastic properties of candidate VE materials using relevant standards. A small-scale tubular cantilever beam will be designed and modeled in Abaqus. The model will be used to perform parametric studies to optimize the thicknesses of the constraining layer and the VE layer. In addition, both steel and carbon fiber-reinforced polymers (CFRP) will be investigated for the constraining layer. The result will guide the small-scale laboratory validation in Stage 2. To estimate damping enhancement, a static loading will be applied to the numerical models, which will be then removed to generate free-vibration responses. A full-scale HMIP structure will be selected from KDOT’s inventory and modeled in Abaqus to perform parametric studies similar to those performed earlier in Stage 1. In addition to optimizing the thicknesses of the constraining and VE layers, an additional study will analyze the impact of the handhole detail, which the CLD must avoid covering. In Stage 2, laboratory and field validations will be carried out for the developed CLD technology. Small-scale tubular cantilever beam will be fabricated and the proposed CLD will be implemented according to the numerically optimized parameters (e.g., thicknesses of the VE and constraining layers). Free vibration tests will be conducted with the tubular cantilever beam before and after the CLD is installed. Free vibration responses will be recorded using an accelerometer to extract damping ratios. Full-scale HMIP will be instrumented with wireless accelerometers, and pluck tests will be carried out to obtain the intrinsic damping of the HMIP. The optimized CLD design will be installed on the HMIP. Particular attention will be paid to proper anchorage of the constraining layer at the bottom of the CLD to ensure full development of shear strain in the VE layer. This will be followed by pluck tests to assess the level of damping enhancement by the CLD.  The final report will include all relevant data, results, and conclusions.