Hello everyone, I have been trying to model a steel frame isolated with friction pendulum bearing (FPB) using Perform 3D software. The link element for the FPB in Perform 3D defines the variation of friction coefficient at the sliding interface with respect to slip rate. The Perform 3D manual states that ‘If desired, the friction coefficient can depend on the slip rate. You can specify up to five slip rates and corresponding friction coefficients. These define a multi-linear relationship between slip rate and friction coefficient’. Whereas other commercial packages like SAP 2000 and Seismostruct define the variation of friction coefficient with respect to sliding velocity using input parameters like coefficients of friction at fast and slow velocities and rate parameter. I could not find proper literature explaining how friction coefficient varies with respect to slip rate and on defining the friction coefficient with respect to slip rate in Perform 3D. I am so thankful if you can help me. With the best regard.