Component based finite element analysis in practice
The component-based finite element method (CBFEM) is a method to analyze and design connections of steel structures. CBFEM combines the standard approach to connection design with finite elements analysis which enables engineers to code-check a variety of steel connections more efficiently.

Structural Code Checking is an automated process that enables the verification of building elements according to codes and regulations for Structural Analysis, Seismic design, Structural Steel design, concrete design, steel connection design, and detailing.

 

Finite element analysis in practice enables engineers to assess connections in a fully integrated model rather than analysing each element piece by piece. Until recently, engineering software only had capability to analyse standard steel connections, so the analysis was not as useful.

 

SMEC has recently used CBFEM to analyse the complex dome structure shown below.  Lead engineer Ei Sheng Hong observes, “The use of finite element analysis enables us to understand the behaviour of each individual steel element at the click of a button. Today we can accurately import 3D data (geometry, member sizes, forces, etc.) directly from global structural analysis software such as STAAD.Pro or MIDAS, which helps to expedite the checking process. By adopting the CBFEM method there is no limit to what engineers can do in relation to plate analysis and structural joints.”

 


Left: BIM view of dome roof structure, Right: Structural analysis model

 

Safety in design and improved cost efficiencies

Invited to offer advice at a prominent government building in Southeast Asia, SMEC was initially appointed to test and verify the safety of replacement roof tiles, which were slightly larger and heavier. It was important to re-evaluate the structural utilization to have confidence that the existing structures could take the new loadings.

 

Steel connection design typically assumes loadings are distributed equally. CBFEM enabled the team to check stress points in the complex steel structure with much greater certainty than traditional approaches.  CBFEM enabled a more accurate assessment of the load distribution which added value through improved safety as well as cost efficiencies in materials and time.

 

By combining the utilisation of all the steel components into one model, the team was able to pinpoint the areas that would require treatment to mitigate stress points caused by the new tiles. The team could determine the size of the plates or bolts needed in each area which resulted in cost efficiencies.

 

Load analysis, evaluation of stresses: red is close to the mega pascal limit. CBFEM is fully integrated with the design which enables efficiencies in materials etc

 

Adding value to the condition assessment process

When working with older buildings this method enables the consultant to quickly assess design compliance to diagnose any possible remedial works. Therefore, CBFEM can be a highly effective tool to supplement building condition assessments. It can identify any structural risks to inform maintenance costs and extend a buildings lifespan.

 

A condition evaluation of existing structures will usually start off with a visual inspection which may identify signs of displacement or cracks. At this point the engineer might obtain as-built drawings to replicate a model of the structure (with the corresponding loadings). If no existing information is available, we can carry out surveys of the site and use laser scanning technology to create a new building model with the right geometry.  Through CBFEM we can quickly undertake connection checks to provide accurate recommendations.

 


Optimized steel connection detail

 

Concrete

The same method can also be used in concrete analysis and design of concrete piers, prestressed beams, crossheads and roof structures. The process is being applied to rail and highway viaducts in the Tengah Interchange, KJE, Singapore and Mass Rapid Transit Line 3 Viaduct, Malaysia.  Keep an eye out for a follow up article on component based finite element analysis in concrete, coming soon.

 

Banner image source: https://www.cbfem.com/