Dynamic Validation of DDBD Procedures for Masonry Structures

Direct Displacement Based methods make use of over-damped SDOF systems, equivalent to the actual structure, to perform either the design or the assessment procedures. The equivalence criteria for masonry structures are discussed in this paper. A constitutive model for masonry structures, able of reproducing the main features of the response also in dynamic analyses, is discussed. Energy dissipation related to ductility is used to set an equivalent viscous damping as a function of the ductility demand. The effectiveness of the equivalent SDOF system is estimated comparing the response of a DDBD procedure with that of full non linear dynamic analyses that make use of several natural and generated time histories, either original and scaled to take into account also severe pga. The outcomes show that DDBD procedures are reliable also for simple masonry structures provided energy dissipation is carefully considered along with the limited values of ductility of masonry