M Amiri - Department of Civil Engineering, College of Engineering, Kermanshah Branch,Azad University, Iran

The existence of initial imperfections in manufacturing or assemblage of real structures is inevitable. Many of these imperfections in double-layer space structures, such as the curvature and length imperfections, are random in nature. In this paper, the effect of initial curvature imperfection in the load carrying capacity of double-layer space structures is investigated. For this purpose, three different types of supports are considered. The curvature imperfection is considered as a random number by gamma distribution. The probabilistic model is used to distribute the random imperfections among all members of the structure. The collapse behavior and the ultimate capacity of the considered structures are determined using nonlinear analysis and this procedure is repeated by Monte Carlo simulation method. Finally, the reliability of structures is determined. The results show that the collapse behavior of double-layer grid space structures arehighly sensitive to the random distribution of initial imperfections

space structures, randomvariable,gamma distribution, initialimperfections, reliability, Monte Carlosimulationmethod