About the project
Comprising four towers spanned by three fabricated steel truss bridges, structure consisted of complex geometry. Using IDEA StatiCa, Dallas Lee, a principal engineer at the Robert Bird Group, and his team gained the precise flexibility needed to model the three-dimensional truss nodes accurately, safely, and efficiently.
The Queen's Wharf Skydeck is constructed from steel and comprises of three spans of 25 m, 30 m and 35 m, bridging between the towers of the development (named IT1, IT2, IT3 and IT4). Two spans (between IT1 and IT2 and IT3 and IT4) are designed with permanent movement joints to allow the independent movement of the connected towers. The IT1-2 span presented a unique challenge. It bridges from the side of tower IT1 from a fixed deck, projecting up to 12 m from the tower’s façade line, requiring a sophisticated articulation joint.
The spans of the Skydeck are assembled and clad at the podium level, then slid horizontally into position via a rail system, before being vertically strand jacked.
Due to the nature of the project, the intersection of those nodes where the trusses connect had become complicated. There was nothing software-wise that Dallas Lee and his team had encountered before that covered those sorts of connections without modeling them from scratch in their FEA program, which was unacceptably slow.
Engineering challenges
There are four towers in the project with a sky bridge between towers IT2 and IT3. The main reason for using IDEA StatiCa was to design the complicated truss nodes within the Skydeck between towers IT1 and IT2 and IT3 and IT4.
Due to the level of complexity in and around these nodes, modelling them in traditional FEA software would have taken too long. They found that IDEA StatiCa was ideal for modeling such connections and doing so quickly.
Another unique aspect to the project is that towers IT 1 and 2 have very different seismic responses, so they move differently. This means, if they had locked the decks between the towers, a lot of internal forces would develop.
To overcome this, they employed an articulation movement joint so the decks can pivot at that point. To achieve this pivot, they used a bearing sitting on a steel corbel inside. This resulted in the need to design very complex bespoke steel fabricated connections in order to achieve this.
During the project, the profile of the deck required particular attention. Previously, it had been shaped like a boat hull in profile. By introducing a crank in both the top surface and the soffit, this meant it was necessary to have very complicated steel connections, where the secondary beam cranks through the primary truss line.
Dallas and his team were also faced with solving some other very creative connections due to the strict architectural decision in how to do the project. IDEA StatiCa allowed them to overcome all these hurdles and gain confidence in their ability to deliver all the connection designs accurately, no matter their complexity.
Solutions and results
The key takeaway from the project for Dallas and his team was the confidence he and his team felt in their designs. Instead of using a normal FEA model, this confidence was due largely to the testing that went on behind using IDEA StatiCa.
They also were able to develop a workflow where they could take the member geometry and member forces from their finite element analysis model. They set up a Python script so they could extract the data from Strand7 into the SAF file format as Strand7 does not have a BIM link. This made it possible to import the model into IDEA StatiCa through Checkbot, which was a huge advantage for the team as this meant they could transfer data without loss using IDEA StatiCa's well-documented API.
In the past, Dallas and his team either had to be more conservative with their design approach, assessing everything manually by hand, applying documented models, and adapting them for a custom connection. Or if they wanted to detail something highly complex, they would create custom-from-scratch finite element analysis models.
Using this workflow, where they were bringing in the member geometries and all the different load cases and combinations, saved them a lot of time. This help them be confident in their designs, as well as push them a little harder.
About Robert Bird Group
Robert Bird Group is a global consulting engineering firm with over 700 employees across eleven offices. A member of Surbana Jurong Group, they are committed to delivering each client’s vision through the relentless pursuit of engineering excellence across all projects. They offer services across five disciplines, drawing upon their international expertise: structural engineering, civil engineering, construction engineering, geotechnical engineering (UK and Middle East), virtual design and construction
The firm won the Public Vote category in the IDEA StatiCa Excellence Awards 2023.
