During the construction of composite steel-tube reinforced concrete bridge piers, safety of the steel cylinders in each group under wind becomes critical. Present design standards don't consider the cylinders of a group to behave as one structure. For that reason the aerostatic characteristics of a group of 9-12 cylinders were studied in a series of wind tunnel experiments. To assess the design wind load during construction for a steel pipe in a group, which are connected to each other by braces and side tie beams, the wind loading for calculation of the sectional forces was investigated. The experimental results show that the aerostatic characteristics of the steel pipe group are influenced largely by the steel pipe spacing. The aerostatic force that acts on each steel pipe are different. However, the sectional force of each steel pipe is almost equal, because the aerostatic force is distributed uniformly due to the connections between the steel pipes. It is therefore possible to calculate the sectional force by using the aerostatic force that acts on the whole steel pipe group. It is to be desired that the design checking should be carried out with selecting the safest wind direction, for which the wind force coefficient of longitudinal direction, transverse direction or the drag coefficient of wind axis is the largest.