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- What is Diagrid Structural System?
- Module Geometry of Diagrid Structural System
- Diagrid Structural System Node Design
- Types of Diagrid Structural System and Materials of Construction
- Advantages and Disadvantages of Diagrid Structural System
What is Diagrid Structural System?The diagrid structural system can be defined as a diagonal members formed as a framework made by the intersection of different materials like metals, concrete or wooden beams which is used in the construction of buildings and roofs. Diagrid structures of the steel members are efficient in providing solution both in term of strength and stiffness. But nowadays a widespread application of diagrid is used in the large span and high rise buildings, particularly when they are complex geometries and curved shapes.
Module Geometry of Diagrid Structural System
1. Diagrid Optimal AngleThe diagonal member of the diagrid carries both shear and moment. So the optimal angle of placing of the diagonals is dependent of building height. The optimal angle of the columns for maximum bending rigidity in the normal building is 90 degree and for the diagonals for shear rigidity is 35 degree. It is assumed that the optimal angle of the diagrid falls in between the both. Usually adopted range is 60 -70 degree. As the height of the building increases the optimal angle also increases.
2. Diagrid Module DimensionsThe module dimensions are majorly two:
- Height: The height of the diagrid depends on the number of floors stacked in one module of diagrid. The common number of floors stacked for module of the diagrids are 2 to 6.
- Base of the module: The base on which the diagrid is formed usually depends on the height and the optimal angle of the diagrid.
Diagrid Structural System Node DesignThe nodes are the important part of the design of the diagrid system. All the diagonal sections are connected to each other by the help of nodes. These nodes are designed for two types of loads, vertical load and horizontal shear. These nodes are joined to the other sections by welding or bolting. It is made sure that very less amount of weld is to be used in the joining. The vertical load is transferred in the form of axial loads from the diagrid members that are placed above the nodes to the gusset plate and stiffeners, then to the diagrid members below the nodes. The horizontal shear is also in the form of axial loads in the diagrid above the nodes, but here one is in compression and another is in tension. The transfer of load is from above the node member to the gusset plate and stiffener and then from gusset plate and stiffener to the members below the node in pair of compression and tension. Due to this load transfer path, the shear forces developed at the location of bolt connection is very high under the time of lateral loads. This may be the shear zone or weak zone of this structure during the earthquakes, the designing of the bolt connections is to be done carefully.
Types of Diagrid Structural System and Materials of ConstructionThe materials that are used in the diagrid construction are based on the following factors.
- Availability of material
- Erection time
- Unit weight of the material
- Labor cost
- Lead time
- Fire resistivity