# A Review of the T-Stub Components for the Analysis of Bolted Moment Joints
## 3 Experimental Testing
In 2012, [PERSON] published his doctoral thesis [42], which was focused on study of the behaviour of T-stub connection by using optical methods to measure the stresses and strains in the elements by three different manners: digital image correlation (DIC), thermo-elasticity, and photo-elasticity. The results of the measures validate the Eurocodes prescription, and also were used to calibrate and validate a finite element model, which was developed for the research. However, the results of the tests showed that the simplifications of the T-stub in the EC do not reproduce the behaviour well, in some cases. The behaviour of the T-stub is well represented in the elastic zone, which is defined by the resistance and stiffness, but in the plastic zone the deviation of the results is higher. In 2016, [PERSON] et al. [22; 43] started studies on asymmetrical T-stub components by testing two types of T-stubs at the Civil Engineering Department of Coimbra University (Portugal). The experimental program tested a total of two T-stubs which were symmetrical and asymmetrical as well. Furthermore, T-stubs were designed to fail according to the failure mode 3 of the Eurocode [1] since the utmost characteristics that were pretended to be observed was the asymmetrical distribution of bolt load and the premature bolt failure due to the asymmetry. The experimental testing results were used to calibrate a finite element model and an analytical model. The results also demonstrated that the asymmetric T-stubs fail for lower loads than the symmetric T-stubs because of the load distribution on the bolts. In 2016, [PERSON] et al. [44] tested 69 T-stub connected to a hollow structural section (HSS) under a cyclic load to characterise the low cycle fatigue response. The specimens were adequately designed to eliminate the flange's bending (\(\text{t}_{\text{f}}=25\) mm), the brittle fracture of the weld and left only two sources of plastic deformation: the flexibility of the HSS column profile and the bolts. The tests were performed in a fatigue testing machine according to the cyclic testing guidance of ATC-24. Therefore, the concept of \"multi-specimens programme\" was used, and the cyclic load was applied in displacement control utilising constant amplitude sinusoidal cycles with a frequency of 0.35 Hz. The characteristics of the connections under cyclic load were evaluated and compared in terms of typical failures modes (failure mode (i) flexural yielding of HSS column face without bolt failure) and failure mode (ii) (moderate local yielding of HSS column wall and bolt fracture), hysteretic load-deformation relation (failure mode (ii) was prone to exhibit a pinching manner in its hysteretic load-deformation curve), and degradation of strength and energy dissipation capacity. Furthermore, the low cyclic fatigue life was analysed according to Eurocode 3 part 1.9 [45] and then reanalysed by taking into account the geometric details of the connection. Finally, a proposed model, which considered the stiffness and energy dissipation, was compared with the commonly used damage models, and it was showed that the new model could give a reasonable prediction of experimental evidence. In 2016, [PERSON] et al. [14] studied the behaviour of T-stubs connected with clamps. For this purpose three specimens were fabricated from IPE220 (S235) and connected to a rigid base through two clamps by means of two high strength bolts (class 8.8). The specimens were tested under a monotonic load, which vary from 0 to 40 kN. In these tests the sizes of the front levers of the clamps were for \"n\" = 5, 15 and 25 mm, with a rear level \"b\" of 16.5 mm, see Figure 11a to see the geometry. These experimental tests were performed to validate an analytical model and to calibrate a FEM model. The results of the tests showed that with the n = 5, the deformation and failure of the specimen is produced by a semi-rigid failure mode, in the case of n = 15 the failure is produced in a combined form, while for n = 25 failure is produced by failure of the bolts. In 2017, [PERSON] et al.