Earthquakes sometimes occur in regions with high population density, which potentially pose threats to human lives and infrastructures. Historically, structural failures due to earthquakes could lead to considerable casualties and severe socio-economic losses. In response, earthquake structural engineering research has advanced to develop mitigation strategies that enhance structural resilience. One approach involves the use of seismic response modification structural components to improve the seismic response of earthquake-resistant buildings. Friction-based structural components have been extensively developed and have been used in various structural applications for seismic response modification purposes over the past five decades. Friction-based structural components offer multiple advantages. They have high initial stiffness, decoupled strength and stiffness, and good energy dissipation capability. They are relatively low-cost and relatively easy to assemble and install. If designed properly, friction-based structural components could be damage-free and immediately reusable after earthquakes.
Despite their advantages, challenges and limitations are associated with the application of friction-based structural components. First, the response of friction-based structural components is highly dependent on the material pair used for the friction interface; therefore, the characterization of the response of friction interfaces is essential for friction-based structural components. Bimetallic friction interfaces were previously widely adopted but considered not practical nowadays because of the galvanic corrosion problem at the friction interface and their unstable long-term performance. Composite-metallic friction interfaces are considered alternatives to bimetallic friction interfaces because of their reduced vulnerability to the galvanic corrosion problem, but the research on composite friction materials for earthquake structural engineering applications is still limited. Second, the response of friction-based structural components has been observed to be sensitive to the machining tolerance of their parts. Without specifying the machining tolerance, the friction-based structural component might generate displacement-dependent friction forces (instead of a Coulomb-type frictional behavior) due to additional friction generated from contacts between the parts. Extra manufacturing processes to fulfill the machining tolerance requirements will require extra time and cost. Moreover, due to the characteristics of the friction mechanism, friction-based structural components typically have a very low (near zero) post-elastic stiffness if not specially engineered. The low post-elastic stiffness could result in increased connection deformation, especially in the application of using friction-based structural components as force-limiting connections between structural systems. The challenges and limitations sometimes make structural engineers hesitant to choose friction-based structural components as a design option.
The objective of my research is to improve the understanding, design, and performance of friction-based structural components in both short- and long-term operation; and ultimately to democratize and advance their applications in earthquake-resistant buildings. To achieve this goal, this research proposes to deepen the study of friction-based structural components through both experimental testing and numerical simulations from three levels: the material level, the component level, and the system level.