In-Plane Failure

In-Plane failure occurs when the ground motion during a quake is in plane parallel to the wall. A telltale sign of in-plane failure is the presence of cracks in the walls that form an X-shape. In-plane failures are caused by quake-induced shear forces which exceed the strength of masonry material. Generally, an in-plane failure alone will not cause a building to collapse. Although a wall may have cracks present due to this type of failure, it usually still has enough strength to support the weight of the building. To prevent in-plane failures in existing URM buildings, the lateral strength of the load-bearing masonry walls must be improved. It´s not done easily on masonry buildings. Sheathing cannot simply be screwed into masonry as it can be with timber. The traditional remedy is to build additional walls that will adequately resist shear loads and attach them to the interior of the URM bearing walls. It´s a very costly procedure.