Study on Hysteresis Model of Welding Material in Unstiffened Welded Joints of Steel Tubular Truss Structure

Abstract

The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of the weld is different from that of the base metal. In order to define the cumulative damage characteristic and study the constitutive behavior of welded metal with the influence of damage accumulation, low-cycle fatigue tests were carried out to evaluate overall response characteristics and to quantify variation of cyclic stress amplitude, unloading stiffness and energy dissipation capacity. The results show that the cyclic softening behavior of welding materials is apparent, however, the steel shows hardening behavior with the increase of cyclic cycles, while the cyclic stress amplitude, unloading stiffness, and energy dissipation capacity of the welding materials degenerate gradually. Based on the Ramberg–Osgood model and introducing the damage variable D, a hysteretic model of welding material with the effect of damage accumulation was established, including an initial loading curve, cyclic stress-strain curve, and hysteretic curve model. Further, the evolution equation of D was also built. The parameters reflecting the damage degradation were fitted by the test data, and the simulation results of the model were proved to be in good agreement with the test results.

Damage Analyses of Replaceable Links in Eccentrically Braced Frame (EBF) Subject to Cyclic Loading

“…The designed parameters of the links are summarized in Table 1. The flanges and web were welded by complete-joint-penetration (CJP) groove welds [39][40][41]. Both the link flange and the web satisfied the provisions for highly ductile members according to the AISC 341-10 standard (AISC 2010a) [42].…”

Lyapunov Exponent‐Based Study of Chaotic Mechanical Behavior of Concrete under Compression

“…e behavior of concrete under loads exhibits the features of complexity and randomness; hence, it could be assumed that concrete might be a chaotic system. e concrete behavior at each moment is influenced by a group of variables related to time, t [32]. ese variables describe the state changing with time, such as stress, strain, and displacement.…”

The Resistance of Welded Joints of Galvanized RHS Trusses with Different Vent Hole Geometries

“…However, the most common truss joints (K-and N-type) have two braces welded to a chord, and the consideration of the actual gap between welds-not only between the chord faces-is essential to evaluating their strength, especially when these gaps are appreciable. Multiple simplified shell models were tested [29][30][31][32][33][34], and the best approximations without increasing complexity were those based on the proposals made by Van der Vegte et al [32] or by Lee and Wilmshurst [33]. The inclusion of the welds in numerical models of steel tubular trusses is also important when considering cyclic loads, as it is necessary in cases where there is some damage to the constitutive model of the welded joints [34].…”

“…Multiple simplified shell models were tested [29][30][31][32][33][34], and the best approximations without increasing complexity were those based on the proposals made by Van der Vegte et al [32] or by Lee and Wilmshurst [33]. The inclusion of the welds in numerical models of steel tubular trusses is also important when considering cyclic loads, as it is necessary in cases where there is some damage to the constitutive model of the welded joints [34]. To obtain an accurate and efficient simulation, the effect of welds in reducing the gap, and thereby stiffening the joint, was ultimately modeled in this research work by means of a ring of shell elements around the braces based on the geometry proposed by the latter authors [33], as presented in Figure 1.…”