Reliability estimation of a Tibetan heritage timber structure with inclination in its Que-Ti joints

Abstract

The reliability of a Tibetan timber frame in a heritage building in Lasha, China is studied. The frame is featured with stochastic Que-Ti joints with inclination. A new method integrating the relative entropy-based probabilistic sensitivity analysis and the Probabilistic Density Evolution Method with absorbing boundary condition is developed for this study. The contributions of stochastic parameters to the probabilistic bearing capacity of the joint can be clearly defined from the differences between the probability density functions of the bearing capacity with different parameter perturbation. Results are obtained via sensitivity analysis with engineering considerations of the heritage frame structure with a large number of uncertain parameters. The Que-Ti inclination angle, column inclination angle, the parallel-to-grain shear modulus and perpendicular-to-grain elastic modulus, which have greater influence on the performances of the heritage frame structure are identified with acceptable computation requirements. A reduced-dimensioned model of the structure with selected variables is then verified and used for the reliability estimation. The structural reliability is noted efficiently implemented with the random variables of the frame system reduced from 13 to 4. The frames in this heritage building with stochastic inclined Que-Ti joints are relatively safe comparing to the recommended reliability limit in the design code.