Numerical model and dynamic analysis of multi degree of freedom masonry arches

A new model is presented for planar multi-block arches subjected to earthquakes. The blocks are assumed to be rigid, and every interface between the blocks may split open and may close, ie, the blocks may impact to each other. During impact, both the classical Housner's approach and improved models with lower energy dissipation are considered. The arch model is verified by comparisons with the available results in the literature. Using the new model, it was found that the circular arch moves as a four-hinge mechanism typically only at the beginning of excitation, and several cracks split open during motion; furthermore, that modeling a multi-block arch by a single degree of freedom (SDOF) four-hinge mechanism may significantly overestimate its collapse load. While, in accordance with the literature, the overturning curves of single blocks and arches with symmetrically located four hinges are similar; for multi-block arches where several hinges may occur they can be very different.