Modified four-hinge mechanism analysis for masonry arches strengthened with near-surface reinforcement

A modified mechanism approach to estimate the load capacity of masonry arches strengthened with near-surface reinforcement is presented. This method is developed for reinforced masonry arches failing with a four-hinge mechanism in which measures have been taken to prevent premature failure by ring separation. The analysis takes into account crushing failure of the masonry and yielding of the steel reinforcement. Hinge positions are varied along the arch barrel and their optimum positions are identified when the minimum collapse load is achieved, in accordance with the upper-bound theorem of plasticity. Validation of the proposed method of analysis is carried out by comparing predictions of the load capacity and failure mode with those obtained from large-scale laboratory tests.