Scan to BIM: from survey to BIM modeling of Calatrava’s Sail
Location: Rome
Client: State Property Agency
Years: 2022 – 2023

INTRODUCTION TO THE PROJECT

The Calatrava Sail was a challenging and exciting project for our team. In particular, for the step dedicated to the Scan to Bim of the Sail, we deployed our technological know-how to translate the survey phase into detailed data and be able to create a complete virtual representation of the built structure and its 46 hectares of land.

In doing so, we have provided a solid basis for the study of the site, its maintenance, and its possible development. The digital model, due to the complexity and size of the work, has been divided into several separate models by blocks.

BIM MODEL PROCESSING

Due to the complexity and extent of the structural works, a preliminary study of the area of intervention was carried out upstream of the BIM modeling in order to functionally characterize the individual models that would make up the federated model and identify all the parts to be reproduced by creating new families.

Their parts were reported in four different models, distinguished by functional blocks and, specifically, according to the works represented and the structural material (steel or reinforced concrete):

– Water polo works in reinforced concrete.
– Sports hall: reinforced concrete works.
– Water polo: steel works
– Outdoor swimming pools

In addition, models were created for the representation of provisional works, subservices, context and landscape, as below:

– Model Context and Landscape
– Model Disciplinary Subservices
– Template Provisional Works

The photographic survey and point cloud made it possible to faithfully represent in the model all the provisional works in the study area, such as crane bases, fall protection guardrails and props. The context model shows the surveyed topography and generic external works such as boundary fences.

All models have been coordinated individually and with each other within coordination and synthesis templates, which group all related graphics, thus enabling them to be managed and visualized in a single environment.

THE PROCESS OF BIM MODELING

The BIM modeling process, which applies to all discipline models, was divided into three stages:

FIRST STEP: Represent all parts of the structures through rationalization derived from consultation of available drawings.
SECOND STEP: The models are thoroughly compared with point clouds and all photographic/video material acquired during the survey phase.
It was determined that for this work, which was deemed incomplete, the above comparison would be deemed sufficient to achieve a percentage of overlap between models and cloud greater than 80 percent.
THIRD STEP: The analysis, also substantiated by additional on-site surveys, identified the parts not yet constructed and those that differed from the reference drawings of the authorized executive design.

CONCRETE STRUCTURE MODELING

At an early stage, the structure was identified and broken down into the following functional blocks:

– Water Polo
– Sports hall
– Outdoor swimming pools

The modeling of the concrete part was carried out by positioning the main grids according to the coordinates on the plotting and geometric coordinate ring drawings of the last approved PE points; this was done with the support of Dynamo, a Visual Scripting and Modeling software that allows customizing the information-related workflow and parameterizing the modeling. Upon overlaying the point cloud, some elements were found to be dissimilar, others incongruent, and still others missing. The grid and main elements positioned through Dynamo were then updated against the point cloud.

At this point, the main structural elements, listed below, were identified and modeled in detail one by one, always keeping the point cloud and all the photographic/video material acquired during the survey phase as the main reference:

1. Floor slabs
2. Bows
3. Beams/Tribunes
4. Pillars
5. Weeks/Walls
6. Perimeter weeks

During the modeling of the various elements, it was necessary to return to the site several times for the purpose of clarifying certain aspects that were considered fundamental.

Modellazione BIM Vela di Calatrava
BIM modeling Calatrava's Sail - Concrete structure

STEEL STRUCTURE MODELING

The modeling of the steel structure was certainly long and complex, reaching the level of detail of the individual bolt.
The entire steel structure covering the water pond was modeled through the development of 14 scripts (Dynamo) for modeling, positioning, and rotation of each individual constituent element of the metal structure. These, starting from the coordinates of each connection with the perimeter AC septa, calculated the generators for the positioning of the tubulars that form the main structure of the sail. To these were then added the transverse and bracing elements that each have different inclinations and rotations. Having finished the “automatic” placement of the main and secondary elements, we moved on to the individual node-by-node connections. All steel elements included in the model were modeled as system families “beams” and “structural connections” appropriately parameterized to meet the different requirements of modeling complex elements such as those of the sail.

At this point, the main structural elements listed below were identified and modeled in detail one by one, always keeping the point cloud and all the photographic/video material acquired during the survey phase as the main reference:

1. Attachment elements to the perimeter baffles
2. Perimeter beams
3. Oblique bracing
4. Horizontal bracing – Lightened beams.
5. Tubulars
6. Connections

These elements were first modeled as families and then inserted into the model as mentioned above. All families have some degree of nesting, containing in the main category other connecting and stiffening elements, such as bolts, plates, and pulls. Each nested family, however, is selectable and queryable, and constitutes its own element properly mapped to the appropriate IFC class and computerized according to the requirements of the Methodological Specification.

So, to achieve a modeling that was consistent with the analytical part, we have tubular IfcBeam elements straight from the base to the central arch and adaptive plate families (IfcPlate) to close the honeycombed areas, inserted by placing control points on the analytical nodes of the beams.

The result is modeling that meets the requirements for defined geometry and effective position as defined by the Methodological Specification and Guidelines.
Selvedges are attached to the converging tubulars to cut the geometry where they meet each other (inside the honeycombed area, not visible from the outside).

BIM modeling of Calatrava’s Sail is a very important phase of a larger project to redevelop, functionally restore and enhance this unfinished architectural structure designed as a multipurpose sports complex by Spanish architect Santiago Calatrava.