Reliability of Single-Layer Space Domes under the Effects of the Changes in the Height-to-Span Ratio

Document Type : Research Article


1 Assistant Professor, Department of Civil Engineering, University of Sistan and Baluchestan, Zahdan, Iran

2 Department of Civil Engineering, Zabol Branch, Islamic Azad University, Zabol, Iran

3 Assistant Professor, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran


Nowadays, the use of space domes has become quite popular compared to other structural forms because they are light and economical and perform well against the applied loads. Since geometry variations determine the loading in space domes, effort has been made in this research to study how the height-to-span ratio variations affect the reliability, sensitivity, and correlation among the random variables in single-layer steel space domes. Applied loads, coordinates of nodes, cross section of the members, modulus of elasticity, and the yield stress are considered as random variables, and the reliability of such structures have been evaluated by the FORM (first-order reliability method), SORM (second-order reliability method), MCS (Monte Carlo sampling), and IS (importance sampling) methods. Results have revealed that FORM yields better solutions and the reliability increases with an increase in the height-to-span ratio. Results have also shown that the random variables’ reliability and sensitivity depend on the performance function, i.e. a change in the latter will change the reliability index and sensitivity coefficient. In domes with a height-to-span ratio < 0.3, the displacement performance function (g_1) is effective and for ratios > 0.3, the stress performance function (g_2) is critical.

reliability index, sensitivity, correlation, performance function, height-to-span ratio


Main Subjects