Cyclic response of low yielding connections using different friction materials

The main goal of the experimental campaign presented is to investigate the dependence of the friction coefficient on some of possible significant parameters. In particular, the 51 tests presented are devoted to evaluate the response of the interfaces taking into account the effect of the bolts preloading, the effect of the type of washers and the influence of the random material variability. In detail, the tests have been carried out with four different configurations of washers (with flat washers and disk springs), considering a possible range of values of the clamping forces (between 40% and 100% of the standard proof preload). The results of the experimental activity are reported in the paper proposing a possible definition of the values of the friction coefficients to be used in design and regression analyses of the experimental data of the slip tests to be used in simplified rigid-plastic modelling for seismic analyses.