Capacity of nonlinear large deformation for trusses assembled by brittle FRP composites

Capacity of nonlinear large deformation is favored for structures because of its indication of potential failure. Such behavior is achieved mainly through material ductility, for example yielding of steel, or so-called pseudo-ductility at the price of progressive failures of structural components. A strategy is proposed in this paper for structures made using brittle fiber reinforced polymer (FRP) materials to achieve such behavior at structural level without the failure of materials. The concept is to take advantage of the post-buckling process of certain structural components in compression, during which the structure loses its redundancy and structural deformation increases as the applied load is sustained. The concept is introduced and illustrated using the analysis of a simple truss. Experiments are then reported which visualize the proposed concept on two FRP truss structures. Experimental results from the first truss demonstrate nonlinear large deformation similar to material ideal elastic–plasticity and those from the second truss exhibit a response analogical to material strain hardening. Possible applications and developments of this concept are further suggested.