Pseudodynamic Tests On Full Scale Masonry Walls

Abstract

To investigate the performance of unreinforced masonry shear walls under earthquake loadings some full scale pseudodynamic tests have been carried out at the Department of Concrete Structures of the Technical University Munich. Thus simulating the main shear wall in the first floor of a four-story building, which was supposed to be constructed on medium soil conditions with an assumed peak ground acceleration up to 1,6 [mls2]. According to the corresponding elastic response spectrum an earthquake ground acceleration timehistory was generated artificially and given as input data to the computer calculating the pseudodynamic algorithm. The used accelerogram with a duration of 9 seconds characterises regions of low seismicity where the design seismic action results from short focal distance earthquakes with low magnitudes. With time and load progress significant stiffness reductions appeared and, as a consequence, the eigenfrequency decreased. Compared with uncracked specimen, the shift in the elastic response spectrum led to reduced loads. The link between the degree of stiffness-reduction and reduction of resulting seismic loads was properly specified using the pseudodynamic test method. The tests indicated, that the current design standards for masonry, based on conventional design methods, were too conservative.