THE USE OF CFRP PLATES TO STRENGTHEN MASONRY ARCH BRIDGES

A mathematical modelling technique is presented that can be used to predict the load carrying capacity of a voussoir arch either with or without CFRP plates attached only to its intrados. The analysis is carried out by applying the upper-bound theorem of collapse to an arch comprising a sufficient number of blocks of masonry to allow collapse to occur in a feasible manner. In order to prevent a hinge forming at the extrados beneath the applied load, CFRP plates can be attached to the intrados of the arch. The formation of a kinematically admissible collapse state requires inward movements of the arch beneath the applied load to be accompanied by outward movements elsewhere. However, the use of CFRP to prevent the formation of an extrados hinge will postpone the development of hinges elsewhere and thus increase the load carrying capacity of the structure. Since CFRP plates are currently considered to improve only the flexural strength, there is a limit to the extent of the improvement in the capacity of the structure. To quantify this, other forms of failure such as shear and crushing are included in the analysis. Finally, the practical application of CFRP to masonry that may be friable, damp, or coated with efflorescence is discussed. For the covering abstract see ITRD E122906.