1 Ph.D student, Department of Civil and Resource Engineering, Dalhousie University, Halifax, NS, B3S 1Z1, Canada, xz601190@dal.ca
2 Associate Professor, Department of Civil Resource Engineering, Dalhousie University, Halifax, NS, B3S 1Z1, Canada, yi.liu@dal.ca
ABSTRACT
In veneer wall construction, the wall ties play an important role in supporting the veneer and transferring the face loads from wind or earthquakes to the backup wall. Wind pressure or suction and seismic loads result in both tensile and compressive forces in ties. The evaluation of the tie force has been traditionally based on tributary area, which results in prescriptive limits on tie spacing. However, some studies have shown that the distribution of forces in the ties is dependent on a range of factors and tributary area based distribution certainly does not reflect the true force in the ties.
The current Canadian masonry design standard prescribe that for a flexible backing, each tie be designed using a load equal to 40% of the tributary lateral load on a vertical line of ties. The rationale for 40% tributary load was based on elastic analysis assuming the tie infinitely rigid in tension and compression.
This paper presents a finite element study on the distribution of tie forces in veneer wall systems. Parameters considered include support conditions for veneer and back-up walls, load application being either pressure or suction, stiffness ratio of the veneer and backup walls, and stiffness and spacing of ties. The effects of these parameters on the tie force distribution are presented. The redistribution of tie force after tie buckling is also studied. The adequacy of 40% rule specified by the Canadian standard is discussed.
KEYWORDS: veneer wall, tie load, tie stiffness, flexible backup wall, Canadian masonry standard, numerical study
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