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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.
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Structures built with unreinforced stone masonry can be vulnerable to seismic activity and show very
low strength as evidenced by several failures in past earthquakes, although most of these structures
did have thick and heavy walls (EERI 2005). The Parliament buildings of Canada are typical historic
buildings that were built with unreinforced stone masonry and possibly warrant seismic strengthening
provided that their heritage values is not affected. The buildings were built on “rule of thumb” in that
no seismic code was developed at that time. Of the Parliament buildings, West Block (Fig. 1) is of
particular interest currently. West Block was built of multi-wythe stone masonry. This type of
construction creates possible bond deficiencies between the wall wythes that affect structural integrity
and consequently the structural seismic performance. The absence of integrity during a seismic event
can lead to wall delamination and wall crumbling (Meyer et al. 2007). It has been deemed that seismic
rehabilitation of old stone structures is warranted in all seismic regions, and tying of the walls needs to
be provided in every case (Tomaževič 2000). Some techniques have been suggested for strengthening
of such heritage structures such as re-bonding, tie-back, reinforcing by means of grouting, and
cemented networks for the masonry (Lizzi 1981). For seismic purposes, strengthening of unreinforced
stone walls by cement grouting is preferred in regions of moderate and high seismic activity.
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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.
-%-" -# & " ./& -&& ,+ /"&&#
Structures built with unreinforced stone masonry can be vulnerable to seismic activity and show very
low strength as evidenced by several failures in past earthquakes, although most of these structures
did have thick and heavy walls (EERI 2005). The Parliament buildings of Canada are typical historic
buildings that were built with unreinforced stone masonry and possibly warrant seismic strengthening
provided that their heritage values is not affected. The buildings were built on “rule of thumb” in that
no seismic code was developed at that time. Of the Parliament buildings, West Block (Fig. 1) is of
particular interest currently. West Block was built of multi-wythe stone masonry. This type of
construction creates possible bond deficiencies between the wall wythes that affect structural integrity
and consequently the structural seismic performance. The absence of integrity during a seismic event
can lead to wall delamination and wall crumbling (Meyer et al. 2007). It has been deemed that seismic
rehabilitation of old stone structures is warranted in all seismic regions, and tying of the walls needs to
be provided in every case (Tomaževič 2000). Some techniques have been suggested for strengthening
of such heritage structures such as re-bonding, tie-back, reinforcing by means of grouting, and
cemented networks for the masonry (Lizzi 1981). For seismic purposes, strengthening of unreinforced
stone walls by cement grouting is preferred in regions of moderate and high seismic activity.
Advanced Materials Research Vols. 133-134 (2010) pp 671-676
© (2010) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMR.133-134.671