Why this matters now
The conference highlighted practical ways to extend the service life of existing steel and composite structures, especially through retrofitting and the reuse of structural steel elements. It brought together scientists, designers, engineers, architects, manufacturers, and students, creating a valuable forum for sharing knowledge on the efficient use of steel in combination with concrete, timber, and other materials. The discussions also covered innovative structural solutions and the ongoing development of Eurocode and international design standards.
The problem we explored
The combination of steel, concrete and timber hasn’t still been comprehensively standardized. The presented paper introduced the research program about the joint between DELTABEAM® Composite Beam and timber slabs. The program included full-scale load transfer tests with timber and composite timber slabs followed by full-scale fire tests. The research program gave deep understanding of how the joint area with all three materials behaves in ambient temperature and in fire scenario.
Our core insight
The full-scale fire tests confirmed that timber slabs can be safely used with DELTABEAM® without additional fireproofing. The results also showed that timber slabs in DELTABEAM® hybrid structures can be designed safely according to Eurocode 5. In addition, DELTABEAM® with cross-laminated timber (CLT) slabs is certified for United States (ANSI/UL 263) and Canada (CAN/ULC-S101).
Key takeaways
- Load is transferred from floor to DELTABEAM® Composite Beam through compression arc against an inclined web in ambient and in fire scenario
- Effective charring depth proved to be less in the joint area than in the middle of CLT slab in all seven cross-sections which were equipped with thermocouples
- DELTABEAM® with CLT slabs fulfilled all loadbearing capacity, integrity and insulation criteria entire 90-minutes (REI90)
- After the two-hour loaded fire test in North America, DELTABEAM® with CLT slabs received UL L902 assembly approval
What this means beyond the event
Many presentations highlighted sustainability and reusability, including solutions such as demountable shear connections for hybrid structures. Fire performance was also widely discussed. These are also important focus areas for Peikko. DELTABEAM® hybrid structures combine composite shallow floor beams with timber slabs offering long spans and high fire performance without the need of additional fireproofing. DELTABEAM® Green uses over 90% recycled manufacturing materials, with environmental impacts confirmed in a third-party verified Environmental Product Declaration. On top of that, DELTABEAM® Green Reuse is also optimized for disassembly and reuse. This shows that Peikko is moving in the right direction as a forerunner in sustainable and reusable construction.
Looking ahead
Sustainability, reusability, fire engineering and structural optimization are expected to become even more important in the future. By using each material where it performs the best and by focusing on standardized solutions, we can create structures that are sustainable, strong and economical. The new generation of Eurocodes gives us an important opportunity to further develop design methods and optimize composite structures.
