Introducing the TC-joint
The Innovation of the TC-joint, replaces the traditional welding in TKY joints delivering a structure with higher fatigue resistance, reduced steel volume, increased lifetime and reduced price. This innovation is developed at the faculty of Civil Engineering of the TU Delft. Since 2017 over 90 wrapped composite joints have been manufactured and tested on various sizes of joints at the Stevin lab. The results of these test conclude that the wrapped composite joint outperforms welds.
The improvement compared to welding is that the load is transferred through a dedicated composite wrap and not through the small surface of the weld. The brace members (diagonals) are bonded to the chord members (legs) through a coupling formed by composite wrapping. The wrap creates a sufficiently large internal bonding surface.
The composite wrap is tailored (length and thickness) to deal with static and dynamic loads transferred by the joint. The optimized, nature-like, shape of the composite wrap, with increasing thickness towards the root of joint, reduces the stress concentration in the composite material and bonded interface, thereby solves issues in fatigue prone/driven design.
A wrapped composite joint is made by application (lamination) of glass fibres on the portions of steel tubes. This provides outstanding bonding strength and flawless quality.
Superior Performance over welded joints
The substantial improvement of the fatigue resistance of the Circular Hollow Section (CHS) joints is achieved by 1) completely circumventing stress concentrations in steel CHS that normally are present due to local wall bending, and 2) avoiding residual stresses, embrittlement and notch effects due to welding.
Double K, double Y and an X joint