Building Sustainable Structures to Weather Any Storm at the Speed of Design

A critical aspect of modern building design and engineering is the role of the fa?ade. These systems majorly contribute to improving the energy performance of buildings, operational cost savings, and providing comfort for occupants. In the early design phases, engineers must consider not only the structural integrity of each building component and their interactions, but also its defense against harsh weather and temperatures.

Simulation technology can help these designers achieve sleekly designed, carefully engineered, and lightweight large-scale structures that meet both energy and cost project requirements while still protecting the interior of the building. To achieve such goals, fa?ade systems, also known as curtain walls, are designed also to transfer external loads like wind loads to the building, and typically strive to be lightweight systems composed of materials such as aluminum, stainless steel, composite, glass and more.

Considering each building-specific weather scenario for these curtain walls during simulation is necessary but poses difficulties to facade engineers. Multiple analyses need to be run such as water infiltration, thermal management, seismic loads, and other weather-related loads. Fa?ade modules on structures are typically replicated several times in a curtain wall system, so it’s important to optimize its performance in terms of material, resistance, and durability.

Conducting the Design Analysis

Using the structural analysis capabilities within Altair? SimSolid?, Ponzio Aluminum performed a mechanical analysis of its own fa?ade module to determine if the design would meet critical safety requirements during a storm event. Engineers also had to determine if the deflection of the sunshade panels induced by wind pressure could cause water infiltration inside the designed module.

Ponzio, a firm specializing in the surface treatment of aluminum, was founded in 1941 as a result of Giuseppe Ponzio’s insight. In almost 70 years of operation, four generations have followed, and the company’s business has developed to include the design and manufacture of systems for hinged and sliding windows, curtain walls, and aluminum accessories for frames. Constantly integrating the most modern technologies and broadening the firm’s signature line of surface treatments has helped the company to become what it is today: an unequivocal reality in the world of aluminum.

Ponzio adopted a five-step workflow:

1.??????Import detailed 3D CAD without simplifications

2.??????Create contacts and assign materials and boundary conditions (kinematic constraints and loads)

3.??????Perform a linear analysis to validate the model

4.??????Assign non-linear contacts and conduct a non-linear analysis

5.??????Review the results to verify stress and maximum gap allowances

[Fa?ade module design by Ponzio Aluminum and a close-up image of the mullion and sunshade]

The fa?ade module was composed of two glass panes, a frame, and three sunshades. Because SimSolid supports CAD models at any stage or format, the imported CAD geometry was fully detailed. SimSolid’s tolerance of imprecise geometry means that unlike CAD-embedded simulation tools, there is no need to simplify complex geometries before analyzing designs.

Below are some images representing the parts that the module was composed of, divided by their material type (steel, plastic, aluminum, and rubber).

When importing the CAD, SimSolid automatically recognized the fasteners, as well as extruded parts and sheets. This improved the quality in terms of connections, fast model setup, and solution performance.

[Steel screws, bolts and nuts (left), plastic components (right)]

[Aluminum mullions, transoms, brackets and sunshades (left), gaskets (right)]

Each material was assigned corresponding mechanical properties to account for their rigidity contribution to the analysis.

SimSolid supports all types of connections in structural simulations, and in this analysis, connections were automatically assigned among the parts. Automatic detection abilities within the software enabled gap and penetration detection among the parts, while users can determine the refinement level of each of the connections.

Conveniently, SimSolid is engineered to take runtimes from minutes to seconds, and with complete accuracy when dealing with large and complex assemblies, so model details were easily added to the geometry. In the next images, the connection points considered for the analysis are marked in red.

[Detailed view of the CAD imported directly into SimSolid without any simplification, and contact points used in the SimSolid analysis]

After setting up the model and defining contact points, wind loads were set to understand if the design was allowing for water infiltration. The wind loads corresponding to a velocity of 150 km/h were applied as a uniform pressure that acted on the external face of the sunshades.

Once the kinetic boundary conditions were added to constrain the anchor plates, the team was able to run the first linear analysis.

As expected, the principal deformation occurred on the sunshield that behaved as a cantilever. Stresses could be studied in SimSolid, but the objective was to understand if this pressure induced by wind in combination with rain would allow water to enter inside the structure.??

[Applied boundary conditions: pressures and constraints, left]

[Displacement contour magnitude of the entire module, right]

During the linear analysis, SimSolid detected that a rubber component of the model could separate as its resultant reaction is in traction, so a non-linear analysis was conducted next to further study the connection.?

[Close view of the displacement contour and nonlinear separating contacts that were considered for the openings (in green)]

In SimSolid, it is possible to switch from a linear analysis to a nonlinear analysis very easily, so in this case, the contacts between the rubber and the mullion were updated as a “separating” contact (the green points in the right-side image).

Results

The results of the new analysis revealed that the maximum opening of the contact was inferior of 0.03 millimeters. SimSolid’s structural analysis abilities combined with the analysis results proved the system to be waterproof, even while undergoing extreme storm events.

[Opening magnitude contour]

Due to how the components were assembled, the sunshades were connected using a special bracket specifically designed by Ponzio, rather than bolted directly onto the mullion. The stress peaks that were discovered on the component were able to be contained under a safety limit. By comparing design scenarios and adjusting model geometry for water infiltration, Ponzio’s team was able to optimize the structure successfully.?

[Stress contour of the most stressed component (within prescribed limits), right]

For designers and engineers alike, SimSolid can efficiently analyze the performance of fa?ade modules while speeding up the design process. SimSolid can also be used for a final validation check of the building’s performance. By eliminating geometry preparation and meshing, the two most time-consuming, expertise-extensive, and error-prone tasks performed in a conventional structural simulation, architectural designers have more freedom to focus on key design elements and analysis results during the building’s preliminary design phase and afterward as a validation method.

Additional architecture, engineering, and construction (AEC) solutions enable engineers to further explore the intermediary building design phases required for the structural analysis and design requirements specific to geographic regions.

For more information on structural simulation, visit https://www.altair.com/architecture-engineering-construction.

The model used is courtesy of Ponzio Aluminum.