Progressive Collapse in Space Structures

Hasanzadeh, Mehran and Gholizad, Amin and Rezaei Moghaddam, Farzad (2016) Progressive Collapse in Space Structures. Masters thesis, University of Mohaghegh Ardabili.

Text (خرابی پیش‌رونده در سازه‌های فضاکار) Mehran Hasanzadeh.pdf Download (1MB)

Abstract

Space structures are a kind of structures which have three dimensional behavior and operation; a system consist of linear elements in positions that can transport loads in three dimensions and load transportation in its elements is almost axially (tensional or compressive). Double layer space structures have a high degree of indeterminacy but they have a brittle behaviour so that damage to an element or to a small part of the structure can propagate in other elements and parts of the structure and cause to progressive collapse. The progressive collapse is a phenomenon in which damage in a small part of a structure propagates in its other parts. In this study a small two dimensional indeterminate truss structure is designed and analyzed. A non-linear static analysis was carried out after the designing of the truss. The results of the analysis represented that with increasing the loads, first group of elements buckles and causes a local collapse without dynamic snap-through. Then with more increasing the loads, another group of elements buckles and the structure collapses completely. Then a dynamic analysis was carried out and under dead and live load, one of the critical elements was removed suddenly. This analysis represented when the critical element removes from the structure, it starts to vibrate but it doesn’t destroy. In next model, a double layer barrel vault with square on moved square plan, with perimeter supports in the length order of the structure was designed. A non-linear static analysis was carried out on this structure too and in two steps with buckling of two different groups of elements, it was collapsed locally without dynamic snap-through and finally in third step with buckling of another group of elements, it destroyed suddenly. In this structure for study of maximum displacement in nodes of the structure when it vibrates because of remove an element, the dynamic reaction of the structure was obtained for removing every element from the structure and then the nodes of the structure that have maximum vertical displacement was identified. In other words it was identified that in which node and for which element remove, the maximum vertical displacement accurses.

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