Structural design on steel roof of the World Expo Cultural Center

The roof structure of the World Expo Cultural Center is a large span truss supported on the inclined frame underneath.Huge suspended load,unusual architectural outline,usable space inside,lower structure mechanics and construction as well should be considered in the structural design for the roof.Structural simplification was first conducted to solve the problem arising from special shape.After comparison of different roof system,considering roof shape,structural mechanics and construction convenience,space truss was finally selected.Ring beams in the support structure and ring trusses in the roof structure can reduce roof deformation effectively without increasing the horizontal reaction of columns.Wind load can be estimated according to Euro code for the flat structure,similar to the roof,based on the comparison between calculation result following Euro code and wind tunnel test.The analysis,considering the counteraction of roof structure and the lower structure indicates that the influence of lower structure on the inner force and deformation of roof is significant enough to be considered in the roof structural design.The construction is divided into two phases according to the boundary of roof,which is sliding in the first phase and hinge in the second.Considering the need of roof stiffness and decreasing the thrust on the lower structure,the maximum and minimum loads added in the first phase are calculated by construction sequence analysis.Design results are that the structure meets the architectural feature and function satisfactorily,and is reasonable in structural mechanics and construction convenience.