Project overview
This project was the connection design for a gridshell in Dubai Media City. Wrenze Steel designed the steel connections, working for Summit Engineering Consultants as client and consultant.
The image from our profile is a finite element model of one of the gridshell nodes. It shows a central hub with several members arriving from different directions, each ending in a round plate, with colours showing how stress is distributed through the steel.
Our scope
Our scope was steel connection design. On a gridshell, the connections are often the hardest part of the engineering, because that is where the geometry is most complex and the forces meet.
Connection design starts from the member forces in the global analysis model. For each node, we take the axial forces, shears and bending moments arriving from every member and check that the hub, plates, welds and bolts can transfer them safely. Where the shape of a node is too irregular for hand calculations, a finite element model of the connection itself, like the one in the image, shows where stress concentrates and whether the steel stays within its limits.
The structure
A gridshell is a curved surface built from a lattice of members. Instead of a few heavy beams, it relies on many lighter members working together, with the curvature giving it stiffness. Gridshells are used for roofs and canopies where a free, flowing form is wanted.
Every node in a gridshell can be slightly different. As the surface curves, the angles between members change from node to node, so connections cannot always be repeated as a single standard type.
Node stiffness matters to the whole structure. A gridshell depends on its nodes to hold the geometry. If a connection is more flexible than the analysis assumed, the shell can deform more than expected, which affects its stability. The connection design therefore has to be consistent with the assumptions in the global model.
Fabrication tolerance is the last check. A hub with many plates at different angles must be detailed so it can actually be made and fitted.
Our article on types of steel connections explains the basics. Request a quote for connection design on your project.
