The Equivalent Ductility approach for designing the structures using Resilient Slip Friction Joints (RSFJs)

Abstract

The innovative Resilient Slip Friction Joint (RSFJ) technology has recently been developed and introduced to the New Zealand construction industry. The RSFJ is a friction-based energy dissipation device that provides the required seismic performance regardless of the material used for the main structural components. It can be used in various lateral load resisting systems including (but are not limited to) shear walls, rocking columns, tension-compression braces, tension-only braces and moment resisting frames. The performance of the RSFJ technology has previously been verified by joint component testing and full-scale experimental tests.

Different design codes around the world have different approaches to determine the design seismic loads yet most of them recommend to reduce the elastic base shear by a factor that is related to the ductility. Most of the codes recommend ductility-related values for different types of conventional structures based on the type of lateral load resisting system and the material used. Nevertheless, there is still lack of information about the seismic design of buildings with more advanced technologies such as RSFJ.

This research aims to provide a simple analysis and design procedure for the structural engineers when designing a seismic resilient building with RSFJs. A step-by-step forced-based design procedure is provided that generally requires the use of the Equivalent Static Method (ESM) to specify the structural design actions followed by non-linear static pushover and non-linear dynamic time-history simulations to verify the performance. In this procedure, the designer adopts a force reduction factor at the start and verifies it at the end. A case-study structure that uses RSFJ braces as the lateral load resisting members is considered to explain and follow the proposed design procedure.