Shahnewaz, Md

Cross-laminated timber (CLT) is becoming a feasible alternative as structural material for midand high-rise buildings. Although CLT walls are appropriate for resisting lateral loads from wind and earthquakes, the current provisions in the Canadian Standard for Engineering Design in Wood lack analytical expressions for estimating their resistance and deflection. In this thesis, the performance of nailed single and couple CLT shear walls is investigated by comparing UNBC test data with the strength and stiffness predictions using analytical proposals. Four methods are considered: Method A (Casagrande et al. 2017), considers the minimum strength value of the hold-down and the vertical fasteners; Method B (Shahnewaz et al. 2019), which accounts for the rocking resistance of all connectors; Method C (Masroor et al. 2020) which accounts for the bi-axial behaviour of connectors; and Method D (Nolet et al. 2019) which describes the elastic-perfectly plastic behaviour of CLT shear walls while neglecting the bi-axial behaviour of brackets. The best match for the elastic behaviour of the nailed shear walls was achieved using Method B, while Method C reasonably predicted the inelastic shear wall behaviour. With the validation against test results, designers should consider using either method depending on the design intentions. Future research should aim at either extending Method B (Shahnewaz et al. 2019) towards the inelastic behaviour or improving Method C (Masroor et al. 2020) in the elastic range.

The widespread availability of Cross-laminated timber (CLT) provides opportunities to extend the use of wood beyond traditional low-rise residential construction. Although previous studies have shown that ground motion duration impacts the collapse risk of structural systems, duration effects are not explicitly accounted for in current building codes, and information on the impact of ground motion duration on the seismic performance of CLT buildings is not available. This study aims to quantify the effects of long duration ground motions on a newly constructed two-storey balloon-type CLT building located in Vancouver, Canada. A three-dimensional numerical model of the building was developed in OpenSees. The shear wall and connections models were validated with test data. 24 pairs of long and short duration records with approximately the same amplitude, frequency content and the rate of energy build up were used for nonlinear dynamic analyses. The building was subjected to the earthquakes in its long (weak) direction. To assess the building’s collapse capacity, fragility curves were developed based on incremental dynamic analysis. The long and short duration motions on average resulted in interstorey drift ratios of 3.7% and 4.8%, respectively, before collapse, indicating that long duration motions are more likely to lead to structural collapse. Similarly, compared with short duration motions, long duration motions increased the probability of collapse by 7% due to the larger number of inelastic cycles. These results suggest that further research is required to further evaluate the effect of ground motion duration on the seismic performance of CLT buildings.