Advanced Structural Analysis with Windas®

By Phey

The highly flexible nature of tensile membranes means that the structures analysed at ADAS are often free-form and irregular as designers strive to create aesthetically pleasing landmarks through elaborate design concepts. Hence, the complexity of these architectural designs, along with their ability to sustain environmental impacts such as wind and rain loadings, form the key concepts for our model development used in analysis.

Non-linear Finite Element analysis 

Linear analysis assumptions are valid for simple structures, but when dealing with complex designs such as pictured below, this would possibly result in a conservative and inaccurate approximation.

Thus, we opt for non-linear Finite Element analysis that is embedded with nonlinear geometrical relations and finite shell elements as an appropriate base in analysing such curved metal structures. The model is also incorporated with proper constitutive models that represent the composition of material properties, forming structural stiffness that is also vital for nonlinear analysis.

In the realm of nonlinear schemes, an incremental load {R} is imposed on the model and generates values for each components of the system equation [K(D)]{D}={R}. The main core of the nonlinear approach lies in updating stiffness through an iterative manner to reach converging solutions by minimising unbalanced load. Constraints are imposed at the structure base and the linearised system equations are solved using the Newton-Raphson quadratic nonlinear solver. The solution generated is able to provide an insight into the structural behavior association with its deformation as well as the local stress and strain of the elements in post-processing.

The maximum principal stress exhibited by the structure is 108Mpa, which is below the material yielding stress at 275MPa. This indicates that the structure has the ability to recover to its original shape after deformation. Furthermore, areas with higher stress concentration in red (stretching) and blue (compressive) zones require further local treatment with acceptable analysis and design considerations.

This advanced structural analysis is executed in Windas®, our in-house software that employs an articulate Finite Element framework. Additionally, we are also able to examine structural stability and dynamic response to provide an optimum structural system in terms of its weight and integrity. Although nonlinear analysis is a useful tool in determining realistic structural response, experienced engineering judgement is still required to perceive the validity of the solution to avoid any design errors.