The domestic research on rectangular-tube flange connection is completely blank

and no design method is given in foreign references.Based on the theoretical formula derived from yield line theory

FEM analysis on loading capacity for both stiffened and un-stiffened rectangular-tube flange connections are carried out by ANSYS

to verify the correctness and accuracy of the theoretical formula.Based on the FEM results

influences of bolts number n

flange plate thickness t and bolts edge distance factor η on the failure characteristics and loading capacity are studied.Design suggestions are proposed as follows: the closer bolts to the pipe-wall the better;adding bolts number is the most useful to increase loading capacity for un-stiffened rectangular-tube flange connections

and increasing flange plate thickness is the best way for the stiffened connections;when loading capacity is met

un-stiffened rectangular-tube flange connections should be used rather than the stiffened type.