Determine and optimize the performance of innovations through test engineering

“Data! Data! Data! he cried impatiently. I can’t make bricks without clay.” This conundrum also applies to innovation, which must have concrete data for development and success. Physical measurement by testing remains the surest way to get this data. The CSTB draws on its test engineering know-how to characterize the performance of building materials and products. Experimentation thus aids the design and reliability of innovation. It can be combined with simulation for a more complete picture. Here is a spotlight on test engineering at the CSTB, which supports innovation in construction by contributing to trust.

The CSTB calls on its test engineers to characterize the performance of innovations and support their design. One of its strengths lies in the design of solutions to meet the needs of stakeholders even if the test does not yet exist. When there is little information available about the behavior of an innovation confronted with certain physical phenomena, test engineering creates experiments to measure the impact on durability and performance.

The process consists, first of all, in avoiding unnecessary tests. The next step is to conduct detection tests, followed by the design of customized experiments. From these exploratory campaigns, combined with digital simulation if necessary, the CSTB derives an original test protocol to reliably characterize the performance of innovation. Stakeholders can then optimize product or system design.

In 2017, the CSTB explored unknown aspects of product behavior, for example, the complex phenomenon of rupture of concrete beams in an industrial building and the adhesion mechanisms of a resin floor covering (blistering). In these areas, the CSTB develops original test protocols for which patent applications are filed.

The CSTB also guides stakeholders in how to improve the performance reliability of their innovations. It is important to anticipate performance variations depending on how an innovative product is installed in a building or component. The CSTB designs a customized test, combined with its calculation software. Example: wind resistance testing of external cladding on a façade. Using simulation, the CSTB models the behavior of the structure subjected to wind and calculates its performance in various configurations. Variations such as the size of the panel, the type of fixing system and number of fixing points per m² are tested. Simulation makes it possible to determine the deformation of the panel depending on the pressure exerted by the wind, and the point at which the wind pressure will cause the rupture of the system.

In addition, test engineering focuses on the tests required to validate computational models, in particular for configurations where performance is less than optimal. The data from the tests serves as a reference data set. It provides knowledge about the product as close as possible to reality, taking into account the characteristics of the industrial product (dimensions, properties, etc.), specific installation conditions for a type of structure and the complexity of the physical phenomena that interact.

At the scale of the building, CSTB test engineering also assesses the performance of innovative components in their environment. The CSTB designs test protocols to optimize the size of the innovative system according to requirements to rationalize the quantities of materials used. In addition, the CSTB has advanced facilities for performing full-scale tests in various domains to provide a comprehensive performance-based approach.

As part of a study of Fire Safety Engineering, for example, the CSTB has developed a full-scale, in situ test to check the fire resistance of an innovative wood-frame aboveground car park. The development of this exceptional test involved determining the size of the car park to be burned, the types of measurements to use and the relevant test case for collecting reliable data. The scenario includes the number and position of cars, the position of fire outbreaks and the path of fire spread. This new test was developed thanks to the knowledge of CSTB experts of the physics of fire and major structures. The results provided a realistic basis to calibrate the simulation model and explore other fire scenarios and types of wood car parks.

Another example, in aerodynamics: In 2017, the CSTB studied the behavior in the wind of a new office tower in the Paris La Défense district, using a hybrid test campaign. The tests conducted in a wind tunnel made it possible to analyze the dynamic behavior of the structure subjected to wind gusts. The CSTB also implemented digital simulations of fluid mechanics to understand how wind flows are structured around the tower. One of the strengths of the CSTB is its dual approach on the safety and comfort of structures, at different levels. The CSTB deploys its customized test engineering, combined with simulation, to better understand, develop and optimize the innovative projects of stakeholders. By considering technical and economic requirements, it promotes greater freedom in construction, in complete safety.