Abstract: In conventional steel shear panel dampers (SSPDs), low cycle fatigue damage usually appears on the weld heat affect zone. A new SSPD with varying cross-sections and no-weld energy dissipation plate was developed, and the shape of which was optimized. 5 new SSPDs were designed and tested in this study. The width and height of the SSPDs were selected as the test parameters. In the tests, the specimens showed different levels of out-of-plane buckling. The degree of buckling depended significantly on the width and height of the new SSPDs. Finite element analyses were conducted to supplement the physical tests. The formulas for the estimation of yield displacement, yield restoring force and out-of-plane deformation are derived based on the results obtained from the physical test and finite element analyses.