Reliability Analysis Of Portal Frame With Semi-Rigid Connect In Typhoon Regions

Typhoon is a type of severe and destructive storm. People's lives and properties will be threatened in areas directly affected by typhoons. The tropical storms, typhoons and violent typhoons generated in North Pacific (including South China Sea) land most frequently in China. Damage or even collapse of buildings occurred frequently in the event of typhoon, most of which are light steel portal frames.Portal frame is the most common used light weight steel system for single story industry factories and civilian buildings.Portal frame is a lightweight structure, in typhoon regions, the wind load is often the critical action instead of earthquake.The beam-to-column connections are usually considered as full-rigid in design procedure. In fact, lots of researches carried out by domestic and overseas academicians showed that beam-to-column connections that most of the commonly used portal frames are semi-rigid. Thus, the frame capacity could be overestimated.The performance of the structures under wind load is in great uncertainty because of randomness of wind load in time,intensity and space, and the effect of structural strength of materials, design and construction process and human factors. Therefore, Structural reliability theory is applied to wind-resistant design. Researches on the reliability of semi-rigid portal frame under wind load are conducted:Statistical test and analysis of data of typhoon in Fujian Province are conducted to verify the probability distribution of typhoon; the wind reference pressure is calculated.The finite element model of a typical portal frame is built in ANSYS with APDL, in which the stiffness of semi-rigid beam-to-column connections are simulated with rotational spring, semi-rigid portal frame with different rotational stiffness subjected to wind load is analyzed. Combined with Monte Carlo Method, degrees of reliability of structures with different rotational stiffness is obtained, reliable indicator for the structure of the main factors and their impact under different conditions are summarized by sensitivity analysis. Based on structural system reliability theory, system reliability of semi-rigid frame under wind load is analyzed.According to the research work issued in this thesis, the resistance capacity reliability can be affected by beam-column stiffness significantly. The capacity reliability of portal frames may be over estimated if designing with the fully-rigid joint assumption. Finally, design suggestions are presented.