The diagrid structural system is a framework made from the crossing of various building materials, including metal, concrete, or wooden beams.
Steel member diagrid structures are beneficial in creating solutions in terms of strength and toughness.
Diagrid is now frequently utilized in large-span and high-rise structures, particularly when intricate structures and curved shapes are present.
In this article you’ll learn:
- Introduction of the diagrid structure.
- Types of diagrid structure.
- Merits and Demerits of the diagrid structure.
- Lots more.
So, if you’re ready to go with a diagrid structure, this article is for you.
What is Diagrid Structural System?
Due to the structural efficiency and aesthetics of the term “diagrid,” architectural and structural designers of tall buildings have the opportunity to explore it.
A framework of metal, concrete, or wooden beams that intersect diagonally is known as a diagrid and is used to construct buildings and roofs.
Purpose of Diagrid Structural System:
- A diagrid structure’s geometry is typically modified to meet the needs of the particular building.
- For a typical range of diagrid structures, this paper’s preliminary design guidelines are intended to be helpful.
- Using a traditional iterative design method, the structurally ideal range of diagonal member angles is first investigated for typical 60, 42, and 20-story buildings.
- A simple and direct method for figuring out preliminary diagrid member sizes is presented and applied to the earlier set of structures.
- Design parameters produced by this process are checked and contrasted with the initial set.
- This methodology produced accurate design variable estimates with little effort.
Types of Diagrid Structural System:
Steel Diagrid Structural System:
Steel is the most popular and widely used material when building diagrids.
Wide flanges, rounded HSS, and rectangular HSS is the most frequently used portions.
The sections’ weight and size are designed to withstand high bending loads as they are simple to erect and don’t take a lot of work to setup.
Concrete Diagrid Structural System:
Concrete is the most typical diagrid material. Both types of concrete diagrids—precast and cast-in-situ are used.
The precast concrete sections’ flexibility enables them to fit precisely within the geometry of the structure.
It also guards against fire damage. Precast concrete, however, contributes more to the structure’s dead load.
Timber Diagrid Structural System:
Timber is the least frequently used component in the construction of diagrids. There are more drawbacks to this material.
The only benefit of this substance is that pieces of timber can be found easily in any shape and size. Low installation costs are involved.
The main drawbacks of using timber as a diagrid building material are its durability and susceptibility to weathering.
Optimal Diagrid Angle Structural System:
The diagrid’s diagonal member is capable of supporting both shear and moment, therefore building height determines the best angle for placing the diagonals.
In a typical building, the columns should be angled at 90 degrees for maximum bending rigidity and 35 degrees for shear rigidity.
It is assumed that the ideal diagrid angle lies halfway between the two. 60 to 70 degrees is the usual adoption range.
The ideal angle rises in proportion to the building’s height.
Diagrid Module Dimensions:
There are primarily two module dimensions:
Height: The number of floors stacked within a diagrid module determines the height of the diagrid, the modules of diagrids typically have 2 to 6 floors stacked.
Base of the module: The height and ideal angle of the diagrid typically determine the base on which it is established.
Design of Diagrid Structural System:
The nodes play a crucial role in the diagrid system’s design. Nodes are used to join together each of the diagonal parts.
These nodes are made to withstand both horizontal shear and vertical loads. Such nodes are bolted or welded to the other sections.
It is ensured that the joining process uses a very small amount of welding.
The diagrid members just above nodes transfer the vertical load as axial loads to the gusset plate and stiffeners before passing it on to the diagrid members underneath the nodes.
Axial loads in the diagrid just above nodes also represent the horizontal shear, however in this case, one is in compression and the other is in tension.
The load is transferred from the member well above the node to the gusset plate and stiffener, and then in pairs of compression and tension from the gusset plate and stiffener to the members underneath the node.
This load transfer path causes very high shear forces to create at the bolt link location during the application of lateral loads.
The design of the bolt links must be done carefully because this could be the shear zone or weak zone of this framework during earthquakes.
Advantages of Diagrid Structural System:
- Using diagrids in building structures significantly enhances the building’s aesthetic appeal.
- When diagrid is used instead of a brace frame structure, the amount of steel used is reduced by up to 20%.
- Since the construction technology is straightforward, it doesn’t require technical labour.
- If the structural material is used, the diagrid makes the best use of it.
- Using glass in conjunction with the diagrid allows for abundant light inside the structure.
- The majority of the exterior and interior of these structures are column-free, allowing for the implementation of unusual floor plans.
Disadvantages of Diagrid Structural System:
- The diagrid system has not yet been fully explored.
- The current crew lacks the knowledge or experience necessary to install diagrids for this construction, which calls for skilled labour.
- Building’s aesthetic appeal is entirely dominated by the diagrid, so only diagrid is used in the design.
- As a single diagrid stack over 2 to 6 floors, it affects the common language of floor-to-floor design.
- Diagrids can only be installed in high-rise buildings.
- Diagrids have an impact on the structure’s economy and safety if they are not properly designed or assembled.
Also read: RCC Framed Structure | Types of Structures | Load Bearing Structure
The diagrid structural system is a framework made from the crossing of various building materials, but the diagonal angles affected the behaviour of diagrid structures.
The ideal range of diagrids angle is between approximately 65° and 75° for 60-story diagrid structures with an aspect ratio of around 7.