الفهرس 
Evaluate the contribution of floor slabs on progressive collapse resistance of the diagrid system.Only 14 pages are availabe for public view
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Abstract
Diagrid system is a structural system in which all external vertical columns are eliminated, leaving just triangular-shaped formed by inclined columns on the building’s façade creating a unique view for the structure. Diagonal members can carry lateral loads and gravity loads due to the triangular configuration by the axial force in diagonal members. The application of exterior diagonals improves the esthetics of the building which in turn attracts the attention of architectural and structural designers of tall buildings. Progressive collapse is the propagation of a local failure from one element to another that causes the collapse of the building or a large part of it due to the loss of one or more load-carrying elements.
Recent research focused on the structural performance of diagrid structures whereas the optimization of structural patterns of the diagrid system against progressive collapse has rarely been investigated in the literature. The main objective of this study is to perform numerical analysis to investigate the effect of the important parameters on the progressive collapse of the diagrid system such as the inclination angle of diagonals, the number of stories, and the location of removed diagonals. Finally, the difference between the two analytical methods, linear and nonlinear are thoroughly investigated. ETABS software is used in the analysis model.
A parametric study is performed by modeling and analyzing a set of models considering 36, 48, and 60 storeys. To determine the optimum angle for the diagrid structural system, four different inclination angles are studied, 50.2º, 67.4º, 74.5º, and 82.1º with 2, 4, 6, and 12-storey modules, respectively. The progressive collapse-resisting capacity of diagrid buildings was evaluated based on arbitrary column removal scenarios according to UFC4-023-03-2009 guidelines and procedures using Alternate Load Path Method (APM). The results generated due to the variation of the above-mentioned parameter were compared in terms of storey displacement, inter-storey drift, storey shear, and percentage of increase in structure weight to find the optimum angle which increase the capability of diagrid structure against progressive collapse. All models were redesigned to detect the most practical and cost-effective angle to enhance the progressive collapse-resisting capacity. Linear and Non-linear static analyses have been performed to make a complete assessment of the analysis. It is found that the diagrid system with 36, 48, and 60 stories with an angle 74.5° provides less storey displacement and the lowest inter-storey drift which reflects more stiffness to the diagrid system, also consumes less tonnage of steel. Diagrid system is more vulnerable to progressive collapse when corner braces are damaged. The Diagrid structure system is compared with the conventional braced Frame system. The study is performed by considering the weights of diagrid structural systems with different diagonal angles with the conventional columns/bracing system. It is found that the diagrid system with an inclination angle of 74.5° saves about (30% - 50%) of the structural building weight compared to the conventional system and when the number of stories increases, the percentage of saving in weight decreases.