ABSTRACT
The chapter reviews a framework for seismic assessment of load-bearing unreinforced masonry (URM) structures. Seismic assessment of a masonry structure must be based on estimations of seismic demand that would be obtained through analysis following prescribed rules that may be executed in an unambiguous manner by a trained professional. When piers deflect in their plane of action, the rotations that develop are owing to a combination of flexural curvature and shear deformation. The "yielding point" may be associated with the exceedence of either of the two strength mechanisms. The nominal deformation capacity of URM walls, u , is estimated according to the following: i. Walls loaded parallel to their plane. The deformation capacity of a URM wall controlled by shear, may be expressed in terms of relative drift ratio and may be taken equal to 0,004 for primary seismic walls and 0,006 for secondary ones.
