In consideration of strong needs for cost-effective seismic retrofit for old houses built in urban areas, proposed is a type of retrofit techniques in which detached houses are linked together by inexpensive materials like ropes, cushions, etc. A system having such linkage exhibit strong nonlinearity even if individual structure behaves linearly. As the first step toward the establishment of the seismic retrofit, a procedure to convert the nonlinear system into an equivalent linear system was developed, and analytical expressions are presented on the equivalent linear stiffness and damping ratio. Associated numerical analyses were conducted, and the accuracy of the expressions was calibrated in terms of the resonance period and the dynamic amplification of the corresponding resonance curves. Examples are presented for the selection of stiffness of linking elements to make the linked system achieve the assigned response reduction, and the effectiveness of the developed linealization is demonstrated.
