Seismic Behavior of Energy-Saving Block & Invisible Multi-ribbed Frame Composite Walls with Different Opening Positions

In order to study the failure modes and seismic performance of energy-saving block & invisible multi-ribbed frame composite wall (EBIMFCW) in terms of hysteretic behavior, stiffness degradation, ductility, energy dissipation capacity, etc., low cyclic reversed loading tests were conducted on six test specimens of EBIMFCW designed in a scale of 1/2 and manufactured with varied opening positions. First, the test results of the specimens were compared and analyzed to determine their failure modes and hysteretic behaviors. Then, the stiffness degradation of each specimen was analyzed using the tangent stiffness calculation method and compared with others, the yield displacement was determined by the graphic method, and the displacement ductility coefficient was calculated using a formula to judge the ductility of each specimen. Finally, the energy dissipation capacity of specimens was studied using the equivalent viscous damping coefficient. Results show that under the horizontal low cyclic reversed loading, a shear-compression failure often occurs to the EBIMFCW with appropriate reinforcement and the failure process can be divided into elastic, elastoplastic and failure stages. The shape of hysteretic loop curve of specimens is relatively full, suggesting that the wall with holes has good seismic performance. Besides, the skeleton curve of the wall with a central opening is descending more slowly and the wall has better seismic performance than those with a non-central opening; a closer opening position to the wall center results in a more favorable contribution of the wall stiffness in the elastoplastic stage and thus a bigger deformation ability of the wall. In addition, the ductility coefficients of the six specimens are all greater than 3, meeting the requirements of the seismic design code; when the opening position is closer to the wall center, the specimen has a better ductility, a larger equivalent viscous damping coefficient, and better energy dissipation performance. Based on the test data, the allowable deformation values of the wall under different performance targets are determined, which provides a theoretical basis for design of EBIMFCWs.