Quantifying safety in structural strengthening design guidelines

A methodology for quantifying the conservativeness in fibre reinforced polymer (FRP) based strengthening of concrete structures is presented. Various types of conservativeness are classified using a systematic framework. The proposed methodology is illustrated using a generalised shear strengthening design protocol. Conservativeness is quantified in terms of relative conservativeness index (/c). Criteria under which the conservativeness associated with FRP material properties does not reach upto the design solutions are highlighted. lt is shown that the design solutions based on TR55, in spite of it specifying relatively high partial factors of safety on FRP material properties, are less conservative than those based on ACI440.