Practical assessment of the seismic behavior of a confined masonry system

摘要

Seismic assessment of the failure mechanisms of masonry buildings can become an onerous task in light of the vast range of typological and structural characteristics of masonry constructions. Ranging from unreinforced masonry old structures that date anywhere from the 19th and early 20th Century, up to contemporary buildings constructed according to modern standards, seismic assessment of masonry buildings challenges the state of the art well beyond the familiar procedures used for Reinforced Concrete and Steel frame structures due to the frequent lack of diaphragm action, their distributed stiffness and mass in the vertical rather than the horizontal elements and the intense brittleness of the material. To facilitate practitioners in assessing the load bearing capacity of existing masonry buildings a practical evaluation procedure was recently introduced by the authors. The procedure allows the determination of the envelope of developed deformations and the tendency for deformation and damage localization throughout the examined building for a given design earthquake scenario, which is then compared with drift capacities of the structural members associated with predefined performance limits. In this paper the assessment procedure is presented through application to two layouts of confined masonry houses, representing many similar structures on the Ionian Island of Cephalonia, Greece, which survived with practically no damage the January 24, 2014 and the February 03, 2014 near-field strong earthquakes of magnitude 6.1 and 6.0 that occurred in the island; these structures were relief-homes made in 1953 under a state of emergency after complete devastation of the island during the 1952 earthquakes of similar magnitude and origin as the 2014 events.