347 / 2019-09-30 23:30:58

Numerical modeling and damage prognosis on industrial RC building for coupled short-term overload and long-term fatigue

计算力学在工程中的应用 > 断裂、疲劳与损伤等行为研究

A large number of reinforced-concrete industrial buildings, which were constructed in the last century in China, have been in service for nearly 40 years. Nowadays they face severe safety challenges, and collapse accidents occur from time to time. The structure diagnosis and performance improvement of existing reinforced-concrete (RC) industrial buildings are now facing new problems. First, the existing fatigue life assessment of structure is concentrated in the design and construction stage. It was impossible to consider the change of load level that actually happens in recent decades. In addition, the damage evolution and fatigue performance degradation of industrial buildings is a nonlinear process, especially in the middle or even later stages of this process. It may bring greater inaccuracy because existing fatigue life assessment generally adopts a linear accumulation method for the fatigue assessment of existing industrial buildings.

A general framework which could simulate damage evolution under the combined action of short-term overload and long-term fatigue loads on RC structure was developed, and was applied on an existing industrial RC building. Due to different damage progressive characters of concrete materials under different loads, two damage constitutive models were introduced in this article and material parameters were determined. For short-term overload as well its dynamic effects, plastic damage (CDP) model is used, while for repeatedly happened long-term loads, high-cycle fatigue damage accumulation model is used. Fatigue damage evolution process for the key components under equal-amplitude long-term load, variable-amplitude long-term load and sudden overload as well, was simulated, respectively. Also, their coupling effects were also analyzed. Results show that the progressive fatigue damage under the variable amplitude load is obviously accelerated, as comparing to the equal-amplitude load situation; overload would aggravates the damage path of the structure, and this effect is more obvious in a long-term sense. This paper provides a numerical method for the safety assessment and quantitative damage prognosis on industrial RC buildings under potentially occurred load combinations during service time.