What do you get when you combine a high-profile residential building at prime shoreline location with a family-run engineering company with a long history? Jätkän Kruunu, an exceptional architectural venture in Jätkäsaari, an old harbour area in Capital region of Finland, features a striking 6-story section and a 14-story tower section. This development comprises 113 units, ranging from studios to four-bedroom apartments, with sizes varying from 30.5 m2 to 123.5 m2. Notable features include balconies, courtyards, rooftop terraces, and sea views. The top tower floors offer residents amenities such as a clubroom, saunas, and a rooftop work and hobby space.
Varied apartment sizes to suit diverse housing needs.
Outstanding shared spaces for leisure, remote work, and events.
Situated in the western part of Jätkäsaari, a vibrant and modern residential area, near future commercial and public gathering areas.
Good access to public transportation, shopping, and educational facilities.
Energy-efficient A-class rating with solar power integration.
Leveraging FEM-Design for structural analysis and design in a complex high-rise building project.
Construction type: An intricate blend of cast-in-place concrete structure with element walls and slabs.
Structural designer: EJT Rakennusinsinöörit Oy
Architect: Huttunen-Lipasti Architects Ltd
Overview of the project. Image credits: Huttunen-Lipasti Architects Ltd
Challenges faced: vertical load distribution, component-level design, and concrete cracking
Vertical load distribution was one of the challenges the engineers at EJT had to overcome.
“The main challenge we encountered revolved around the load paths of the horizontal load. These loads, especially those caused by the high-intensity coastal winds (more common in autumn and winter) on the structure, demanded ingenious solutions to be effectively distributed and transferred to the foundations of the building,” says Joonas Jaakkola, M.Eng, Project Engineer at EJT-Rakennusinsinöörit Oy.
Loads distribution for one of the tower’s floors. Image credits: EJT
Tekla model of the project. Lower 6-story part and high-rise 14-story part. Structure supported by pilings. Image credits: EJT
“We relied on FEM-Design’s load distribution algorithms and edge connection handling to tackle this challenge. We conducted rigorous load analysis, ensuring that every structural element was optimized to carry its calculated design load. We calculated wind loads in the highest coastal wind load class to fine-tune our load distribution models further,” adds Joonas Jaakkola.
Achieving structural stability while accommodating the architectural intricacies of the building required meticulous attention to component-level design, including the walls, columns, and slabs.
“FEM-Design’s capabilities were pivotal in modeling these complex components accurately. Detailed finite element analysis model allowed us to assess stress concentrations and load-bearing capabilities at critical joints within the structure. This level of detail enabled us to optimize reinforcement layouts and ensure that each component could withstand the imposed loads effectively,” says Joonas Jaakkola.
Besides the challenges with vertical load distribution and component-level design, EJT engineers focused on calculating concrete cracking.
“Given the building’s impressive height, modeling of concrete cracking was crucial. To ensure compliance with the comfortability criterion, lateral displacement, and vibration, we adopted a safe side method of tripling elastic non-cracked deformations, demonstrating our commitment to safety and uncompromised quality. The challenge of controlling concrete cracking was addressed through software and manual calculations. FEM-Design’s cracking analysis tools provided valuable insights into potential crack locations and widths. These results were cross-verified through manual calculations, ensuring that our approach was conservative and aligned with design codes,” says Joonas Jaakkola.
All the FEM calculations in the project were done in two different models: the tower and the lower part. This was made possible because the two buildings are separated from each other with movement joint and because they were designed in different consequences classes, which have effects on load combinations.
FEM-Design models for the lower 6-story part and high-rise 14-story part. The smaller part of the building had hollowcore slabs (FEM-Design hollowcore model) and the high-rise part had cast on situ slabs and element walls. Image credits: EJT
Why they chose FEM-Design for this project
“Our choice of FEM-Design was initially influenced by our familiarity with analogous software tools and FEM-Design’s well-earned reputation for its advanced concrete structure design capabilities and especially element building modeling capabilities. There wasn’t a particular feature that led us to choose FEM-Design. Instead, we quickly recognized its adaptability and potential to elevate our project and its suitability for these projects. Joonas has previous experience with Dlubal’s RFEM software in similar projects and was able to use FEM-Design easily, even though this was one of his first projects with FEM-Design,” says Marko Haikarainen, B.Eng, Project Manager.
Strengths and advantages of FEM-Design
FEM-Design’s concrete structure design capabilities, particularly for slabs, walls, and reinforcement, helped the engineering team get the necessary precision and proved user-friendly. These proved instrumental in the project’s overall success.
The software’s finite element analysis capabilities in element types of structures facilitated the accurate modeling of concrete structures, both whole frame and slabs. It allowed the engineers at EJT to simulate real-world load scenarios, assess stress distribution, and optimize reinforcement layouts. Additionally, the software’s non-linear analysis capabilities were crucial in evaluating structural behavior under varying load conditions.
“A defining feature of FEM-Design was its remarkable flexibility. This versatility allowed us to swiftly tweak reinforcement and structural elements and modify the structure, providing invaluable agility in fine-tuning the design to harmonize with the project’s unique demands. Moreover, easy modeling was a key part of the productivity we needed for big projects like this,” adds Marko Haikarainen.
The software’s prowess in concrete section design was a standout feature, offering an efficient and streamlined approach to slab design that effortlessly met ULS and SLS requirements.
FEM-Design model of the tower’s roof floor. Image credits: EJT
“The ability to make real-time adjustments to the design parameters and instantly observe their impact on structural performance was a game-changer. We leveraged FEM-Design’s flexibility to modify the structure manually and do iterative calculations to explore multiple design scenarios efficiently. This iterative approach ensured that our final design was structurally sound and optimized in terms of material usage and construction efficiency,” concludes Marko Haikarainen.
EJT is a well-established Finnish civil engineering firm with a history of 30+ years. It specializes in both renovation and new construction projects, having successfully completed over a thousand projects. The company’s expertise lies in the structural design and construction of residential buildings, and it has a reputation for delivering high-quality work.
Count on FEM-Design as your go-to concrete structure design software
With FEM-Design, you get an effective tool for designing both Reinforced Concrete (RC) and Precast Concrete structures. Whether you’re inspecting objects in a comprehensive 3D modeling setting or analyzing them element by element in a 2D perspective, the design process for reinforced concrete is fast and straightforward. The engineers at EJT used FEM-Design’s concrete design module optimally for the Jätkän Kruunu project.
Read more details about FEM-Design’s concrete design module here. Are you eager to use FEM-Design as your go-to concrete structure design software?