UBC Theses and Dissertations
An efficient approach to evaluate seismic performance and reliability of wood shear walls Gu, Jianzhong
Performance-based engineering and design aim to achieve multiple performance levels under different hazard levels. There is a need to define and quantify structural performance in a reliability based format for managing risk and uncertainty. The tedious process of nonlinear dynamic analysis of shear walls requires an efficient tool to predict the drift with acceptable accuracy. A simplified mechanics-based analog model was developed for such purpose. The similarities of the load-displacement curves of individual nail connectors and shear walls indicate it may be possible to represent the shear wall behaviour with a large pseudo nail. To develop a pseudo nail model, a nonlinear optimization problem which minimizes the error of prediction is involved. Five search methods were implemented in solving the optimization problem: hill climbing, random search, genetic algorithm, simplex and artificial neural network. The input of the model is the load-displacement relationship of the structure subject to a half cyclic static load with the decreasing curve after peak load. Results from laboratory tests and validated models of two types of regular panel shear walls were used to verify the accuracy of this model. Good agreement was obtained. The uncertainty of structural performance is attributed to many sources of randomness. The combined effect of earthquake intensity and ground motion records, were considered in this thesis where wall drifts were considered as the performance measure. The drift demand distribution of a structure was formulated and a popular format of reliability procedure was discussed. A new reliability procedure based on conditional distribution at given earthquake records was established. Another procedure, the Monte Carlo method considering weighted ranking, was proposed to improve the efficiency of simulation when intensity measure is arbitrarily sampled. The construction of confidence curves is also presented for the analysis of structural performance. Both the pseudo nail model and the reliability procedures were implemented to calculate the reliability indices of eight types of Japanese walls. The results can be used for engineering practice and to guide the modification of building code.
Item Citations and Data