Abstract. The diamond bird-beak TX-joint is a novel configuration for tubular structures and there are few correlated papers for it. Non-linear FE analysis is carried out on axially loaded TX-joints in order to study the local static behavior of this type of joint. The individual influence of the following geometric parameters on the joint capacity, section width ratio β of brace to chord members, section width to wall thickness ratio 2γ of chord member, and wall thickness ratio τ of brace to chord members is made clear. Increasing either β or τ will enhance the joint capacity and increasing 2γ will lower joint capacity. A reduction equation is proposed to consider the load effect of chord and the axial forces of out-of-plane braces. The tension of out-of-plane braces always lowers the ultimate capacity of joint. The same tension and compression have the equal influence on the joint capacity.

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Transportation plays an important medium role in the COVID-19 epidemic spread, and correctly understanding this role will help to prevent and control the epidemic spread among different areas. This paper analyzed the process of the COVID-19 epidemic spread through transportation channels at home and abroad, and made a comparative analysis of the epidemic development before and after taking traffic control measures in different countries around the world. After clarifying the role of transportation channels in the epidemic spread, we simulated the epidemic development under different traffic control measures based on the SEIR disease dynamics model. The results show that, without traffic control measures, the peak value of infected people will appear earlier. If strict traffic control measures are taken, the simulated lines of the latent and infected people will almost disappear, and the epidemic will soon stop. Our research results provide a theoretical basis for formulating reasonable traffic control measures.