Optimisation of Cable Dome Structure Design for Progressive Collapse Resistance (original) (raw)
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In this paper, a new framework of form finding and structural optimizations for tensile domes was developed using a cutting-edge parametric modelling tool Grasshopper in Rhino. The detailed exploration of this new techniques is presented. It is found that the use of this parametric tool allows a more intuitive, rapid and flexible design. Structural optimisation of the member sizes, topology and surface can be explored easily at an initial design stage in a project. Therefore, the proposed new framework provides a more effective and efficient way for form finding and structural optimization. Based on the new method, a prototype Tensile dome which is to replicate the existing Tensile Dome Georgia dome is designed and analyzed. The structural behavior of the cable domes is investigated. Using this new framework, two ellipse shape Tensile domes with new geometrical configuration are developed. They exhibit enhanced load bearing capacity, therefore can be used the future long span structure projects.
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Progressive Collapse Analysis of Cable Stayed Bridge considering Different Cable Geometry
Journal of emerging technologies and innovative research, 2017
Bridges is the lifeline and important structure for any nation. Cable-stayed bridges are one of the most popular long-span bridge type due to its structural efficiency and pleasing aesthetics. Stays of cable-stayed bridges are critical structural elements which are subjected to corrosion, abrasion, wind, vehicle impact and malicious actions and these extreme loading scenarios may lead to severe damage and loss of cable which demands the progressive collapse analysis. Progressive collapse is a continuous spread and enlargement of initial local failure of structures, which is characterized by a disproportion between the initial failure and its resulting widespread collapse. Several bridge accidents occurred in recent years have demonstrated that the consequences of progressive collapse may be unpredictable and serious. It has been found that the ability to resist the collapse is determined not only by structural load-bearing capacity, but also by other structural attributes. Although great efforts have been contributed to the progressive collapse of building structures, comparably small attention have been paid in the same problem about bridge structures. In this research Xing jia bridge is consider with different geometry fan type , harp type & semi harp type cable system. Analysis of cable stayed bridge is done using computer programme SAP. Results obtained in form of Time period, Displacement and axial force are compared for different cable patterns. The results of the comprehensive evaluation of the cable failure show that the tread of the progressive failure of the cable-stayed bridges decreases when the location of the failed cables is closer to the pylon.
Design Optimisation of a Cable–Strut Tensile Structure According to the Importance of Elements
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In this study, the design of a flexible cable–strut tensile structure was optimised according to the importance of elements to achieve high structural robustness. First, the importance coefficients of elements were determined by comparing their structural prefailure and postfailure strain energy. Moreover, the effects of the external load, the initial prestress, and the cross-sectional areas of elements on the importance coefficients were analysed. Second, a genetic algorithm was used to optimise element section design and minimise the maximum importance coefficient. Third, an optimised cable arrangement scheme was developed by adding an alternative load transfer path to the outer hoop cable with the highest importance coefficient. In this scheme, outer elements have a Levy-type arrangement rather than a Geiger-type arrangement so that a Geiger–Levy composite cable dome is formed. Finally, the cable arrangement and element section design for the aforementioned scheme were comprehens...
Structures, 2020
The sudden rupture of cable is one of the factors that can threaten the bridge safety; causing progressive collapse due to severe vibrations along with numerous changes in the internal forces of all bridge members. Therefore, analyzing the bridge behavior after the sudden cable rupture and estimating the maximum response of the bridge members is of great importance. According to Post-Tensioning Institute (PTI), the sum of the static analysis responses of two models can be used instead of dynamic analysis of cable rupture. In one of these models, the ruptured cable should be removed and twice its tensile force should be applied at the two ends of the cable. In this study, an approach proposed for investigating the tensile force coefficient (TFC) of the ruptured cable in the model of cable rupture effect. For this purpose, an optimization problem was defined to minimize the difference between the static and the maximum dynamic analysis results. The performance of the proposed approach is illustrated with a three-span cable-stayed bridge. This problem was solved for the rupture of each of the bridge cables under examination at different durations of cable rupture using ECBO meta-heuristic algorithm. Moreover, this meta-heuristic algorithm was used to adjust the tensile forces of the cables. Based on the results, a general form of equations was found between cable rupture duration and TFC, which the maximum of it, is in accordance with the PTI coefficient. According to this equation, increasing the cable rupture duration reduces this coefficient.
Optimized Design of Steel Buildings Against Earthquake and Progressive Collapse Using Cables
International Journal of Progressive Sciences and Technologies, 2018
Progressive collapse is a procedure in which local failure of a structural component can cause failure of the overall structure or a smaller part of it. This phenomenon is the subject of intensive investigation by researchers the last decade. This work presents a design of structures against earthquake and progressive collapse. Cables are used as means to achieve the desired structural performance when the buildings are subjected to (a) seismic excitations, (b) accidents which result in failure of structural members. The design strategy is based on the use of cables located in suitable locations in the structure. The element sizes and cable topology are attained by an automatic optimization procedure in an effort to achieve the most effective use of structural materials. The effect of various design constraints is evaluated in the performance of the optimized buildings. The analysis results indicate the promising potential of cables as a means to increase the building's progressive collapse resistance, as well as a promising alternative to typical bracing sections used in practice.
Disproportionate collapse analysis of cable-stayed steel roofs for cable loss
International Journal of Steel Structures, 2011
Disproportionate collapse has been identified lately as a real cause of failure for structural engineering projects. Rare and unexpected, the phenomenon of disproportionate collapse usually results to many fatalities and thus, its analysis and mitigation is deemed necessary. This work describes the analysis of a cable-stayed steel roof under the scenario of a cable loss. The event of a cable loss is assumed to be brittle, while relevant recent recommendations suggest the application of a scaled equivalent static force at the points of the anchorage of the cable but in the opposite direction of the original cable force. In this paper, three different conditions have been considered in order to study the effect of the cable loss into the overall structural response of a typical cable-stayed roof; the level of the equivalent nodal load in the opposite direction of the original cable force varies. The steel structure of the roof, in its complexity, closer to responding as a cable-stayed bridge rather than a steel roof provides a useful template for conclusions; several topics regarding disproportionate collapse and cable losses are discussed.
A unique feasible mode of prestress design for cable domes
A numerical method is presented for initial prestress design of various cable dome structures with multiple independent prestressed modes. A new and robust approach for the purpose of obtaining a unique feasible prestressed mode is proposed by systematically increasing or decreasing the number of member groups and/or directly assigning some linear relations on the force densities between some specific groups until the unique feasible prestressed mode is found. On the other hand, these manually assigned linear relations can allow designers more control over the prestress design. Evaluation of the stability for the structure is also considered. Numerical examples are presented to demonstrate the efficiency and robustness in obtaining a unique feasible prestressed mode for various cable domes.
Advanced form-finding for cable dome structures
2010
A numerical method is presented for form-finding of cable domes. The topology and the types of members are the only information that requires in this form-finding process. Dummy elements are used to transform the cable dome with supports into self-stressed system without supports. The eigenvalue decomposition of the force density matrix and the Singular value decomposition of the equilibrium matrix are performed iteratively to find the feasible sets of nodal coordinates and force densities which satisfy the minimum required rank deficiencies of the force density and equilibrium matrices, respectively. Based on numerical examples it is found that the proposed method is very efficient, robust and versatile in searching self-equilibrium configurations of cable dome structures.
The Effects of Geometrical Properties on Progressive Collapse in Cable-Stayed Bridges
2020
Cable-stayed bridges play a key role in the sustainable development of regions. In recent years, various kinds of these bridges, in terms of cable arrangement, have been built. Due to harsh conditions of their surroundings, several hazards always threat cable-stayed bridges one of which is the progressive collapse phenomenon which may give rise to disastrous events like disproportionate deformations or entire collapse and huge damages. This paper, consequently, aims to determine the effect of geometrical characteristics of this type of bridge on progressive collapse and introduce the best arrangement to deal with it. For an investigation of this phenomenon, assessment is carried out by non-linear time history analysis using SAP2000v17. The axial force of adjacent cables, therefore, will be evaluated within 0.1 second-step under specific load combination proposed by PTI recommendation in order to compare it with the ultimate limit. It can be concluded that the dimension of the deck a...