HETEROGENEOUS LIMIT ANALYSIS FOR MASONRY ARCH BRIDGES WITH FULL MODELING OF BACKFILL

Masonry arch bridges are widespread architectural heritages worldwide but are vulnerable to many disasters, such as floods and earthquakes. Understanding the failure mechanism of these bridges is very important. Recent works regarding the collapse analysis of masonry arch bridges almost neglected the backfill, whose absence will lead to inaccuracy in numerical simulation. This contribution discusses how to model the backfill when analyzing the collapse of masonry arch bridges in heterogeneous limit analysis. In this paper, the collapse of the bridge with triangular, random Voronoi, and centroid Voronoi mesh of the backfill is first compared. For such purpose, we in a prior extend the formulation of standard heterogeneous limit analysis to be applicable to arbitrary polygon elements. Then, we compare the collapse performance of the bridge employing an associated or non-associated sliding model at the interface of the backfill. The results show that although the employment of polygon elements for backfill can produce a more realistic crack propagation, it may also lead to severe locking problems, resulting in an overestimated load prediction. Besides, we would recommend employing a non-associated flow rule for a conservative prediction of collapse load (especially when using a polygon mesh).