SEISMIC CONSIDERATIONS OF DUCTILE COUPLED SHEAR WALLS WITH OPENINGS

This paper describes the results of an analytical study of linear and nonlinear behaviour of ductile coupled shear walls with openings, unde r seismic loading. The walls in a typical building were studied and as sumed to be ductile. They were designed, calculated, and detailed in c ompliance with the National Building Code of Canada 1990 (NBC) and the Canadian concrete code CAN3-A23.3-M84. The results of the elastic ana lysis show, as expected, that the concentrated force at the top specif ied by the NBC does not accurately simulate upper-mode effects, at lea st for this type of structure. A spectral analysis covering the five f irst modes, as described in the NBC, seems more suitable for coupled s hear walls with openings with a period of more than 1.5 s approximatel y. The results of the nonlinear analysis show that application of the overstrength factor to the wall as recommended by CAN3-A23.3 greatly i mproves its behaviour and prevents tensile failure of the wall, althou gh it does not always guarantee the desired sequence of plastification in the case of severe earthquakes. Application of the factor does, no netheless, limit plastification of the wall to lower levels and keeps rotational ductility in beams and walls to a reasonable level.