Mechanics of MEXE method for masonry arch bridge assessment

The assessment of the load-carrying capacity of a masonry arch bridge has traditionally been undertaken using the Military Engineering Experimental Establishment (MEXE) method (or a modified version of this), which has its roots in idealised elastic structural modelling. This method has been supplemented by alternative techniques which have emerged over the last 25 years. These techniques have highlighted some apparent shortcomings of the MEXE method. The present paper presents a full derivation of the fundamental equations published by Pippard, which were used to underpin the MEXE method. These equations are studied in the light of the perceived shortcomings of the method and extended to present new equations that might be used for more general application. Conclusions are presented that will be useful to the assessing engineer.