Drift Capacity of Walls Accounting for Shear: The 2004 Canadian Code Provisions


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Title: Drift Capacity of Walls Accounting for Shear: The 2004 Canadian Code Provisions

Author(s): P. Adebar

Publication: Special Publication

Volume: 236


Appears on pages(s): 151-170

Keywords: concrete walls; displacement-based design; drift capacity; seismic shear; shear design

Date: 5/1/2006

The new provisions in the 2004 Canadian code for flexural displacement capacity of concrete walls, and the new provisions for seismic shear design of slender concrete walls are presented. To facilitate explanation of the seismic shear provisions, general expressions for shear design are first presented, and the non-seismic shear design provisions in the Canadian and ACI 318 building codes are briefly reviewed. According to the new seismic shear design provisions presented here, the maximum shear force and concrete contribution depend on the inelastic rotation demand in the plastic hinge, and the compression stress (critical crack) angle used to determine the quantity of horizontal reinforcement depends on the axial compression stress applied on the wall. The 2004 Canadian code provisions generally require more horizontal reinforcement than the ACI 318 provisions except when inelastic rotational demand is small and axial compression stress is large; however, the Canadian provisions permit significantly higher shear stress for high-strength concrete walls. The new provisions can be used to design concrete walls given the expected level of drift demand or, as demonstrated in this paper, can be used to estimate drift capacity of walls accounting for the significant influence of shear.