Seismic design and evaluation of high-rise concrete shear wall buildings in Canada

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The long-term objective of this research program is to reduce the hazard for people living and working in high-rise buildings in Canada. Metro Vancouver, which will eventually experience a large earthquake, has more high-rise buildings than Seattle WA and Portland OR combined. Many of these shear wall buildings were built prior to modern seismic design requirements being adopted in Canadian building codes.***The research involves development of the methods engineers need to evaluate the seismic safety of existing buildings and design new buildings. The research program involves a number of related projects. Many previous projects from this long-term research program have resulted in significant changes to the Canadian building codes and the HQP that have been involved are in high demand by engineering companies that do this type of seismic evaluation and design.****Over the next five years, the projects will include:****Seismic safety of older existing buildings with thin concrete walls. Such buildings contribute significantly to the seismic hazard in Canada because of their prevalence, high occupancy and the likelihood that they will not perform well in an earthquake. Unlike buildings in the US, many of the older buildings in Canada have thin concrete walls as the seismic-force resisting system and the gravity-load resisting system. Two projects will be done - one looking at the global response of buildings using nonlinear dynamic analysis accounting for the typical non-symmetrical arrangement of walls, and a second looking at the influence of discontinuities using nonlinear finite element analysis.****Development of a rational model for the shear resistance of concrete walls subjected to earthquake loading. One of the greatest challenges engineers face when evaluating existing buildings or designing new buildings is providing sufficient shear resistance of concrete walls subjected to earthquake loading. The current methods were developed from tests with gravity loads applied for many hours. New laboratory tests will be conducted on simulated shear walls to determine the shear resistance of concrete walls subjected to earthquake loading. The walls will be subjected to a complex pattern of first mode displacements and a complex pattern of higher mode shear forces determined from nonlinear analyses of buildings. The shear resistance will depend on how the demand is calculated, e.g., single maximum shear force pulse during an earthquake.****Evaluation of shear wall building foundations. Shear walls in new buildings often extend through many levels below grade before reaching the foundation, while older buildings often have shear walls supported directly on shallow footings. Research will be done to refine the prediction of nonlinear foundation rotations and the force distribution in the highly indeterminate system when shear walls extend through numerous below-grade diaphragms.**