On the rational design of the top wind girder of large storage tanks

•The design approaches for the top wind girders in SH3046 and API650 were presented.•3D model is established to simulate the real distribution of wind load.•The strengthening effects of the tank bottom is considered.•The top wind girder designed according to SH3046 and API650 is too conservative.

In this paper, simplified mechanical models for the design of the top wind girder of large storage tanks adopted in the codes SH3046 and API650 were presented to show their differences regarding the wind load magnitude and action zone. Finite element models for the tanks were built to study the strengthening effects of the bottom constraints. It is found that for a large storage tank with a small ratio of height to diameter, the strengthening effects of the bottom constraints are significant and should not be ignored. If based on two-dimensional models without considering the strengthening effects of the bottom constraints, the strength design of the top wind girder according to the present codes of SH3046 or API650 is too conservative.