Analytical Model for the Investigation of the Out-of-Plane Behavior of Unreinforced Masonry Walls

Introduction & Objective Load-bearing and non-load-bearing unreinforced masonry (URM) is used for many types of buildings in Europe and all over the world. In nuclear power plants (NPP), non-load-bearing partition walls are often built as URM. While for ordinary building structures, static load-bearing capacity verification is sufficient in many cases, for NPP's there are high requirements on the earthquake-resistant design. The building structure itself as well as substructures and secondary structures need to be stable in case of an earthquake. Although, in most cases, only secondary non-safety relevant elements or structures (e.g. cable trays or piping systems) are anchored or fixed to partition walls, their collapse however can be a risk for safety relevant structures and components, due to falling debris or sequential effects (Class Ha structures/components according to KTA 2201.1 [1]). Therefore, it must be verified that there is no risk of collapsing walls or falling debris. For this purpose, in-plane and out-of-plane (Figure 1) load-bearing capacities are required to be determined. Since the out-of-plane capacity (stability transverse to the plane) often is decisive in an earthquake scenario, it is investigated here.