The imperfections in Double Layer Grid Space Structure (DLGSS) threaten the safety of designs. The imperfections in the member length of DLGSS may result from human-based causes such as manual cuts, tolerance sensitivity in CNC cuttings and variation in temperature. Therefore, analyzing the impacts of imperfections is vital to ensure the safety of DLGSS systems. Thus, a safe design of DLGSS against member length imperfections is the main focus of this paper. A novel and practical safe design approach, which considers member length imperfections, has been proposed based on linear elastic and probabilistic analyses methods. The impacts of member length imperfections on the DLGSS behavior were also evaluated in detail. Variation in positions of imperfect members, initial size of length imperfections (longer or shorter than the ideal size) and number of imperfect members were selected as the parameters to be analyzed. A 3D computer program, which considers the initial length imperfections of members, has been codded to analyze the space trusses. The impact of imperfection on a space structure was investigated by repeating the simulations for stochastic dispersion of imperfect member position and initial member length imperfection. The results revealed that initial length imperfection might have a considerable impact on the DLGSS behavior. The DLGSS systems can safely be designed by employing the proposed design approach to overcome the defined imperfections.

双层网格空间结构（DLGSS）中的缺陷威胁到设计的安全性。DLGSS成员长度的不完美可能是由人为原因引起的，例如手动切割，CNC切割的公差敏感性以及温度变化。因此，分析缺陷的影响对于确保DLGSS系统的安全至关重要。因此，针对成员长度缺陷的DLGSS安全设计是本文的重点。基于线性弹性和概率分析方法，提出了一种考虑构件长度缺陷的新颖实用的安全设计方法。还详细评估了成员长度缺陷对DLGSS行为的影响。不完美成员的位置变化，选择长度缺陷的初始大小（长于或短于理想大小）和缺陷成员的数量作为要分析的参数。考虑到构件的初始长度缺陷的3D计算机程序已经编写完成，以分析空间桁架。通过重复模拟不完全构件位置和初始构件长度不完全的随机分布，研究了不完全对空间结构的影响。结果表明，初始长度缺陷可能会对DLGSS行为产生重大影响。通过采用建议的设计方法来克服定义的缺陷，可以安全地设计DLGSS系统。已被迫分析空间桁架。通过重复模拟不完全构件位置和初始构件长度不完全的随机分布，研究了不完全对空间结构的影响。结果表明，初始长度缺陷可能会对DLGSS行为产生重大影响。通过采用建议的设计方法来克服定义的缺陷，可以安全地设计DLGSS系统。已被迫分析空间桁架。通过重复模拟不完全构件位置和初始构件长度不完全的随机分布，研究了不完全对空间结构的影响。结果表明，初始长度缺陷可能会对DLGSS行为产生重大影响。通过采用建议的设计方法来克服定义的缺陷，可以安全地设计DLGSS系统。