ARCH 653 Building Information Modeling in Architecture

Project 1 - Parametric BIM

Case Study: Allianz Arena at Munich, Germany

I chose the Allianz Arena in Munich, Germany as my Parametric BIM Project for ARCH 653 course at Texas A&M University. This is a football stadium in Munich, Bavaria, Germany with a 75,024 seating capacity designed by Herzog & de Meuron Architekten of Basel, Switzerland.

Figure 01: Axonometric view of the stadium (Source: http://footage.framepool.com/en/bin/947343,allianz+arena,munich,germany,aerial/)

Modeling Process

The overall parametric modeling process included four major steps:

Creating parametric conceptual mass family driven by set of parameters and formulas.
Making the curtain panel (pattern based) family according to actual building design and controlled by well-defined parameters.
Creating the parametric envelope (façade) family based on curtain panel and conceptual mass family.
Creating BIM project model by loading the parametric family

Parametric Conceptual Mass Family

First of all, to crate parametrically-controlled mass for this stadium by using Revit conceptual mass family, available roof plan and section has been analyzed to establish some relationships. Aim was to create a parametric mass model which can be changed by different parameter values without compromising architect’s design intent and overall scale/proportion of the existing building. For example, identifying the relationship among stadium length, width and height as actual drawings or dimensions of the building were unknown.
I decided to use “stadium width” as a user defined parameter and a set of relationship was established with respect to stadium length and radius of the corner curves of the stadium.

Stadium Length (A) = 1.24 * Stadium Width (B)

Figure 02: Roof plan analysis to set parametric relationship between length & width of Arena.

(Source of original roof plan: http://imgarcade.com/1/allianz-arena-stadium-plan/)

Process:

After analyzing the roof plan and section, few major parameters (mentioned below) were identified to create the base plan of the arena with the help of parametric equations/formulas and constraints.

Stadium Width = B
Half of Stadium Width (B/2) = user defined
Corner Radius of Stadium (a1) = 0.25 * Stadium Width
Half of Stadium Length (A/2) = 0.37 * Stadium Width
Stadium Length = 2* Half of Stadium Length + 2* Corner Radius of Stadium

Figure 03: Parametric formulas in Revit Conceptual Mass family

All reference planes were aligned with respect to two major central reference planes (Figure 04). After setting up all the parametric equations, model was flexed by changing the values.

Figure 04: Parameters for the base plan of the stadium

In next step, to create the parametric 3D mass, Revit point family has been incorporated with the generated curve of the stadium plan (Figure 06 & 07). After analyzing the roof plan with the section (Figure 05), it is evident that another relationship can be established between the length (A) of the stadium, with the height of the stadium.

Figure 05: Comparative analysis between plan and section to establish parametric relation.

Analysis led towards the generation of another set of parameters in accordance with the previously set parameters. And then, stadium seating has been arranged in three tiers and each tier depth is parametrically driven by level height (which is related with stadium height).

Level height = user defined parameter.

Stadium lower tier depth = level height /tan 24⁰
Stadium middle tier depth = level height /tan 30⁰
Stadium upper tier depth = level height /tan 34⁰

In addition to that, the projection of stadium roof overhang is being parametrically driven by the length of the stadium (A).

Overhang of stadium roof = (halfA1 + a1) - (Stadium_Tier_Lower + Stadium_Tier_Upper + Stadium_Tier_Middle)

It is relevant to mention that, all vertical reference planes were aligned with respect to central vertical axis. And, this complete model was flexed to verify these parametric relationships (Figure 07).

Figure 06: Section analysis of Allianz Arena

Figure 07: Stadium section driven by set of parameters for parametric BIM.

Finally, the parametric 3D mass has been generated by selecting the parametrically driven profile and the closed path of stadium plan by ‘create form’ function (Figure 08).

Figure 08: Parametric conceptual mass family of Allianz Arena.

Parametric Curtain Panel Family

To create similar façade pattern like existing Arena, ‘Rhomboid’ pattern has been selected in the Revit curtain panel family. Then a parametrically driven frame and panel has been generated to create diamond-shaped cushion top panel. It is worth to mention that, material parameters for both frame and surface panel have been created in this family (Figure 9).

Figure 09: Parametric curtain panel family

Parametric Building Envelope

First of all similar surface pattern (Rhomboid) has been generated on the conceptual mass family by dividing specific surfaces. Then, to create parametrically driven façade, two parameters have been associated with the distance of U-grid & V-grid (Figure 10).

V grid = User defined

U grid = 0.5 * V grid

Figure 09: Parametric envelope (façade) of Allianz Arena

Then, previously generated curtain family has been loaded to create the final parametric envelope family. User can change the depth of curtain panel, thickness of curtain frame, length and width of each panel.

Finally, BIM project has been created after loading the Revit family into the Revit Project interface. Then floor plans, ground surface has been created. Audience seating were placed in different levels after loading the inbuilt family of Revit. Afterwards, respective materials have been assigned on previously created material parameters

Figure 10: Renderings of Parametric BIM Project

Critics on Revit modeling application

Parametric modeling in Revit was quite challenging experience. One of the major problems that I encountered was during conceptual mass family generation phase. The four corner curves of stadium base plan weren’t changing while the width of the stadium was being changed. This happened due to incorrect snapping of either vertical or horizontal edge lines, though every time I was selecting the start point of curve when the ‘end snap of reference line’ was showing. After several trials, finally I could manage to resolve this issue. It was really frustrating to do this simple step several times when I was sure that I was doing this in a correct way.

In addition to that, another problem I faced when I was creating the parametric 3D form in conceptual mass family. When I was hitting the ‘create form’ after selecting the parametric profile and parametrically driven closed loop of stadium base plan the error message was showing up about ‘self-intersecting geometry’ (Figure 11). Then I realized that this occurred when the length of roof overhang exceeded the radius of the corner curves in plan. After that, this has been resolved by changing few parametric equations with incorporation of “if statement”. This was still happening when the depth of the stadium was setting lower 600 ft, however before creating the solid form all these parameters were working correctly.

Figure 11: Error message while creating parametric 3D mass

Finally, in creating the parametric façade (envelope), making the pattern close to existing building was challenging. Rhomboid pattern seemed more similar when the width has been set half of its length. But the major challenge I faced was in creation of seamless consistent pattern throughout the stadium façade, i.e. both vertical wall surfaces and horizontal roof surfaces. Because at the intersection of two curved surfaces, panels weren’t meeting properly. However on the top surface I could manage to make a consistent pattern by changing the grid rotation in some panels, but the transitions were hard to manage. I tried several options in creating the smoother surface, where the best result was creating continuous spline through points. Still in this option, inconsistency was evident where facades met. I believe this happened as Revit breaks up the solid surfaces according to its sweeping path while creating the 3D mass.