Sixteen shear-type friction dampers were made and tested under cyclical loading to investigate the effect of the lap gap on the frictional resistance of the damper. The test results have indicated that the frictional resistance of a shear-type friction damper depends not only upon the tensile force by the high-strength bolts that clamp the slipping steel plate but also strongly upon the lap gap. Based on the experimental results, a formula for assessing the effect of the lap gaps on the frictional resistance of the damper was developed. Comparisons between the measured frictional resistances and the predicted ones have indicated that the frictional resistance of a shear-type friction damper with lap gap could be evaluated by the proposed formula very well.
