REINFORCEMENT OF MASONRY WALLS SUBJECTED TO SEISMIC LOADING USING STEEL X-BRACING

A design criterion is proposed for the seismic reinforcement of masonr y stuctures by joining shear walls with steel X-bracing. The seismic r esponse of the coupled system was investigated in the time domain by a step-by-step integration. Two suitable mechanical models for the shea r walls and the X-bracing were used. A wide parametric analysis was pe rformed varying the mechanical characteristics of the masonry walls as well as the X-bracing. Using 20 simulated ground motions the uncertai nties related to the definition of seismic loading were taken into acc ount. The results obtained established a structural design criterion b ased on the equivalent static lateral force method. Given this criteri on, the structural factor of the steel X-bracing had to be reduced. Th is reduction was necessary due to the mixed matched interaction of the two different seismic behaviors. The reduction was based on a suitabl e coefficient, named the ''coupling parameter.'' This coefficient is g iven in specific graphs proposed for design purposes.