AbstractConsidered nonstructural elements, infill walls and their participation in earthquake resistance are often neglected in structural design, which leads to deviations in the predictions of seismic responses. Generally, infill masonry walls are the most extensively used type, but they often exhibit out-of-plane vulnerability and insufficient reliability during earthquakes. To overcome the drawbacks and further improve the beneficial contributions of infill walls, a reinforced concrete (RC) infill wall isolated by polyvinyl chloride (PVC) tubes, abbreviated as PVCIW, was proposed to incorporate with coupled shear walls. Featuring flexible connections, the PVC tubes were adopted to eliminate the unfavorable constraints between infill walls and the main structure. RC panel was adopted for the infill because of its excellent compressive properties and out-of-plane resistance. Compression of the PVCIW was allowed during extreme quakes to contribute to anticollapsing of the coupled shear walls. Cyclic loading tests were applied to compare the hysteretic properties between coupled shear wall specimens equipped with RC infill walls, PVCIWs, and without infill walls, and the advantages of PVCIWs were validated. Finite-element analysis (FEA) was performed to simulate the test results, and parametric cases were investigated to optimize the design of PVCIWs. Finally, based on a modified coupling ratio CRM considering the influence of PVCIWs, a new seismic design approach was developed to obtain the optimized properties of this novel system.