ABSTRACT
This chapter presents the application of limit principles, derived from the plastic analysis of steel structures, to the masonry arch. It discuses analysis of the safety of masonry arches based upon their geometry. The chapter also discusses the effect of geometry changes due to yielding of the abutments. The voussoir arch bridge at Pontypridd, completed by William Edwards in 1751, collapsed during the course of construction after the removal of the centering. C. S. Chettoe and W. Henderson made direct heavy loading tests on a large number of bridges. The classic problem of arches in the eighteenth century was precisely that of their thrust against the abutments. In the limit the perfectly flat arch has an infinite geometrical factor of safety, but also, of course, an infinite abutment thrust as the thickness decreases to zero. Detailed investigation of the voussoir arch itself was only of interest insofar as it led to some method for estimating the value of that thrust.
