Lattice damping wall system using torsional steel tube dampers at the crossing position is proposed. As indicated in the Fig. 1, this system composed of vertical steel bars, horizontal steel bars, and circular steel tubes. In this study, the formula for evaluating elastic stiffness of damping wall system considered stiffness of lattice bars is introduced. Then, validity of the formula for evaluating elastic stiffness is verified by FEM analysis and experiment of pure shear partial model arranged 4 steel tubes.
 The model considered the calculation of the stiffness of damping wall system represents damping wall system installed in center-to-center of column-beam frame. It is shown in Fig. 2. The deformation of damping wall system consists of deformation of circular steel tubes and one of lattice bars, as shown in the Fig. 3. Torsional deformation causes in circular steel tubes, and bending shear deformation causes in lattice bars. The model to compare FEM analysis with calculated value is the same. The model of FEM analysis consists of beam element. As indicated in the Fig. 5, the calculated stiffness and full plastic shear strength correspond to the analysis result.
 The test specimens are partial model arranged 4 steel tubes. It is shown in Fig. 6. The parameters of test specimens are thickness of steel tubes, length of steel tubes, thickness of lattice bars, and width of lattice bars. In this experiment, pure shear type loading device was used for cyclic loading, as shown in the Fig. 7. In the cyclic program, all test specimens showed steady hysteresis behavior.
 From the results of test and analysis, the following findings were obtained.
 (1) The formula for evaluating elastic stiffness of the damping wall system correspond to the result of FEM analysis. The model of FEM analysis consists of beam-element. The full plastic strength calculated the formula driven also correspond to the result of FEM analysis.
 (2) The ratio _eK/_cK (experimental values/calculated values using the formula introduced) of elastic stiffness of the damping wall system introduced to one of the test result is 0.91 to 1.06.
 (3) The ratio _eQ_p/_cQ_p (experimental values/calculated values using the formula introduced) of full plastic strength of the damping wall system introduced to the test result is 0.82 to 0.87. There is some possibility of an effect of welding heat.
 (4) In this experiment, equal torsional deformation caused in the four steel tubes in the elastic region. Because, in the elastic region, shear strains calculated from the values of tri-axial strain gauges passed on in side of them showed equal values. In the plastic region, the shear strains of steel tubes aren't equal. However, the four steel tube dampers share torque equally.