Seismic performance improvement of existing RCFs using external PT-PBSPC frame sub-structures: Experimental verification and numerical investigation

A novel external sub-structure is developed for the seismic performance improvement of existing frame buildings, namely, post-tensioned precast bolt-connected steel-plate reinforced concrete frame (PT-PBSPC frame). The mechanism and design of the sub-structure are introduced, and the pseudo-static experiments are conducted based on 4 scaled frames to verify the technique details (e.g., precast or monolithic, with or without prestress) as well as the macro responses (e.g., failure patterns, hysteresis curves, strain developments, self-centering capacities). The simulation model verified by the experiments is given, and the numerical elements and materials are compared to indicate the distinct varying tendency as well as the necessary detail selection. The parametric study is also performed to extend experimental work and to further discuss the different con-trolling parameters. Generally, the experiments prove the equivalent-performance to the mono-lithic specimen as well as the high-efficiency of the external precast-assembly operation. Superior functions of prestressed tendons are verified in view of hysteresis behaviors and indices analyses (e.g., peak capacity improvements and residual deformation reductions). The simulations sup-plement with the test data, recommend the main factors for the passive control design, and provide the model base for the further performance explorations and technique applications of the PT-PBSPC frame in the earthquake-prone areas.