Economic Analysis of Double Layer Barrel Vault Space Structures in Form, Modulation, and Ratio to Different Spans.

Space structures, especially double-layer caskets, have been widely used to cover large spaces. Due to the large number of members and joints in space structures, choosing the appropriate form and modulation has a great impact on weight loss and thus reduce the cost of the structure. On the other hand, the minimum weight does not always mean that the structure is economical, and other parameters such as the number of connection nodes, the number of members and also the amount of material wasted will have a significant impact on the final cost of the structure. The purpose of this paper is the economically optimal design of two-layer cast iron space structures based on the study of various parameters such as the weight of the structure, the best shape and the ratio to the opening of the cast iron. For this purpose, 28 models in common forms of this type of structures with two-way and oblique networking in different modulations of 2 and 3 meters and in the ratio of openings between 0.2 to 0.5 in Formian software and then models under different combinations of code loading regulations , Analyzed and designed in SAP2000 software. In the following, the forms that have violated the constraint of resistance or displacement have been discarded and the economic comparison of the approved forms with considering the number of nodes and excess members in each model has been discussed in order to influence the form, member modulation and span ratio in Optimize the weight and how it is distributed between the columns and members of the network and the cost of this type of structures to be shown and the best model with the most economical to be determined as an engineering design. The results show that the two-way form on the two-way with a modulation of 3 meters and a ratio of 0.3 span compared to other forms studied, significantly reduces the cost of the design and is the most economical design.