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Net section rupture is a common failure mode of bolted tension members. In particular, the net section capacity of tension angle is significantly affected by the effect of shear lag. This paper reports the tensile test results of twelve high strength steel angles and six normal steel angles of grade S690 and S275, respectively. The test parameters included steel grades, connection length (bolt number) and out-of-plane eccentricity. All the specimens were failed by net section rupture. Finite element (FE) analysis was used to simulate the structural behaviour of the test specimens and to further interpret the test results. The test and the numerical analysis results showed that the test efficiency of tension angles, which was defined by the ratio of the ultimate test load to the calculated net section resistance, was sensitive to the material ductility and the connection details (i.e. out-of-plane eccentricity and connection lengths). The effectiveness of the available design specifications for quantifying the net section resistance of S690 steel angles was evaluated. A design approach proposed by Yam and colleagues considering the influence of material mechanical characteristics and connection configurations was also revisited. It was found that the current design specifications produced inconsistent predictions of net section resistance of tension angles, whereas the method proposed by Yam and colleagues gave good predictions of net section resistance of bolted S690 steel angles. • Structural performance of bolted S690 and S275 steel angle is examined. • The influence of steel grades and connection configuration is studied. • Test observations are strengthened by finite element model results. • Design comments are proposed. [ABSTRACT FROM AUTHOR]

A new type of Fe–Mn–Si alloy damper is developed in this study to enable significant enhancement of the low-cycle fatigue (LCF) resistance compared with conventional metal dampers. A set of material tests was conducted first to foster a good understanding of the basic mechanical properties of the Fe–Mn–Si alloy, followed by a comprehensive experimental study on 18 shear damper specimens, considering different materials, connection types, restraining conditions, and loading protocols. A numerical investigation was also conducted to help interpret the test results. Among other important findings, the study reveals that the Fe–Mn–Si alloy exhibits a non-obvious yield plateau followed by noticeable strain hardening under monotonic loading. The fracture strain attains 57.4%, showing good ductility. Under cyclic loading, the Fe–Mn–Si alloy dampers exhibit different failure modes compared with their normal steel counterparts. The former mainly fails in fracture near the center of the plate, whereas the fracture of the latter tends to initiate from the edge. Importantly, the Fe–Mn–Si alloy dampers show fatigue life and total energy dissipation capacity up to 10 times that of their steel counterparts. Using buckling-restraining plates brings further benefits to the fatigue resistance and energy dissipation capacity. A combined kinematic/isotropic hardening model is shown to adequately capture the hysteretic behavior of the Fe–Mn–Si alloy material, where calibrated parameters are given. Finally, building on the findings from the present study, future research opportunities regarding the analysis and design of Fe–Mn–Si components, including their weld and heat affected zones, are highlighted. [ABSTRACT FROM AUTHOR]

• The novel structure showing the partially self-centring behaviour was proposed. • A spectral energy factor model for the system was developed based on the lognormal distribution assumption. • The sufficiency of the energy factor model was justified. To achieve a delicate balance between self-centring behaviour and energy dissipation, it was proposed to develop the damage-control steel frame equipped with shape memory alloy (SMA) connections and ductile links showing the partially self-centring behaviour. This paper examined the inelastic seismic demand of the novel structure, and the emphasis was given to the spectral energy factor of the system subjected to near-field earthquake motions. Based on single-degree-of-freedom (SDF) systems representing the novel structure and a near-field earthquake database, nonlinear spectral analyses were performed considering a wide range of structural period and hysteretic parameters, and more than 25 million energy factors were obtained. The probabilistic characteristics of the energy factors were examined in detail. The analysis database confirmed that the energy factors were sensitive to structural period and hysteretic parameters. In addition, a right-skewed distribution feature of the energy factors was observed. Thus, a spectral energy factor model for damage-control steel frames equipped with SMA connections and ductile links was developed using the lognormal distribution model. Nonlinear regression analyses were conducted to develop a series of prediction equations. The good agreement between the histograms of the energy factor and predictions by the regression equations confirmed the adequacy of the proposed model. The proposed model was eventually applied to evaluating the damage-control behaviour of a prototype structure under near-field earthquake motions, and the sufficiency of the model for assessing the structural damage-control behaviour from a statistic perspective was confirmed. [ABSTRACT FROM AUTHOR]