CAMPOS, DOMINGOS1; GUEDES, JOÃO2; LOPES, VALTER3

1) Civil Engineering student, FEUP, ec07118@fe.up.pt

2) Assistant Professor, FEUP, Department of Civil Engineering, jguedes@fe.up.pt

3) Civil Engineer, NCREP – Consultoria em Reabilitação do Edificado e Património, valter.lopes@ncrep.pt

The brittle behaviour and the low strength of stone masonry under tensile forces make this material particularly sensitive to seismic type actions. During an earthquake, a masonry structure is submitted to important and fast variations of stresses that tend to deteriorate mortar between stone blocks decreasing strength and stiffness, either to horizontal or vertical forces. Past events indicate that this is particularly relevant when seismic actions include vertical accelerations with high amplitude (near-site earthquakes). In this case, there may appear, although instantly, tensile strains at the mortar interface, splitting masonry into macro-blocks and increasing its vulnerability to seismic actions.

To help understand the influence seismic vertical actions may have on the behaviour of stone masonry structures when combined, or not with horizontal seismic actions, two simple structures were subjected to simulated earthquake loads through finite elements and using a continuous damage material behaviour model. Through the combination of different vertical and horizontal seismic actions defined by artificial ground acceleration time histories fitting EC8 spectra, it was possible to estimate conditions where vertical accelerations seem to have more influence on the response of stone masonry structures.

Keywords: Masonry walls, seismic behaviour, vertical seismic action, damage model.