Reliability-based investigation into the duration of load effect for the design of timber structures based on Chinese standard

Abstract

The duration of load effect is a widespread phenomenon that timber structural members will experience certain decrease in strength under long-term service, which should be properly considered during the design of timber structures to ensure the lifetime structural safety. This paper presents a series of reliability-based investigations into the duration of load factor for the Chinese standard of timber structures. Firstly, the load models including dead load, live load and snow load were set up, and the main features of the load models were validated according to the requirements in Chinese load code. Then, the Foschi and Yao’s damage accumulation model was calibrated with long-term experimental data, and the calibrated duration of load model was validated by comparing the cumulative failure probability with different intensities and durations of sustained load. Based on the validated load models and the damage accumulation model, the short-term and long-term reliability was calculated using JC method and Monte Carlo simulation, respectively. Finally, recommended values of the duration of load factors were obtained under different loading conditions, including dead loads only, dead loads plus live loads, and dead loads plus snow loads. The presented research aims to provide technical basis for the determination of duration of load factors for the design of timber structures, therefore ensuring the structural safety of timber structures under long-term service.