On the Dynamic Behaviour of Strengthened Stone Masonry Walls

摘要

Unreinforced stone masonry is common in heritage structures worldwide. Unfortunately, these structures are susceptible to failure or severe damage when subject to dynamic or seismic loading. Conservation of historic structures is a challenge as the heritage and cultural values need to be preserved while the advent of new seismic codes may require major strengthening to be implemented. The new seismic codes demand high seismic strength and ductility for such structures, whereas neither the strength nor the ductility of an existing stone masonry building can be quantified easily. The Parliament buildings of Canada fall into this category. Therefore, an extensive experimental program was carried out to investigate the dynamic and seismic behaviours of stone walls representative of Canada's Parliament buildings. The walls were constructed of double stone wythes with the cavity between being filled with weak mortar, shards and small stones, constituting a rubble core of the walls. The experimental program included in-plane quasi-static, free vibration and high frequency loadings, together with out-of-plane shake table tests. The tests were aimed at investigating the integrity, strength, damping, stiffness degradation, and ductility of the walls. Different potential strengthening methods were assessed, methods that would minimize structural intervention and preserve the heritage values of the building. The methods involved different metallic anchors and traditional stone interlocking to tie the two outer wythes together. Fortunately, the stone walls exhibited satisfactory performance in all cases. In addition, the test results suggested that plain un-strengthened stone walls had strength and other characteristics similar to those of the rehabilitated walls, in the range of the imposed load scenarios.