Abstract
Behaviour of the inverted triangular truss, which is widely used as a bridge girder, was investigated analytically and experimentally. Cold-formed square hollow cross-sections of steel grade S355J2H with dimensions 80 mm × 4 mm, 90 mm × 4 mm and 40 mm × 4 mm were selected for the top and bottom chords and bracing elements of the truss with 12.56 m span, correspondingly. Five FEM models were developed using software Dlubal RFEM. The main specific feature of the models is the difference in modelling of joint behaviour considering plastic behaviour and stiffness of truss connections. It was shown that the FE model of the truss where the members were modelled by the truss type finite elements and the joints modelled by the shell type ones allows predicting behaviour of the truss with precision of up to 3.9%. It was shown that precision of the suggested FEM model grows 4.36 to 4.62 times in comparison with the traditional FEM models where the members were modelled by the truss finite elements with the pinned and rigid joints in case of plastic joint behaviour. Precision of the suggested FEM model is identical to that of the traditional FEM models regarding the case of elastic joint behaviour.
Highlights
Triangular steel trusses with hollow sections are widely used in bridge and roof structures as truss girders due to their increased spatial stability and decreased material consumption in comparison with the planar trusses (Durfee, 1987; Gao, Bai, Jiang, Wang & HE, 2018)
Bridges with triangular trusses are characterized by decreased material consumption and corresponding dead weight compared with the rectangular truss bridges (Belevičius, Juozapaitis, Rusakevičius, Misiūnaitė & Valentinavičius, 2017)
It was shown that the FEM model of the truss where the members were modelled by the truss type finite elements but the joints - by the shell type ones allows predicting the behaviour of the truss with precision of up to 3.9% in the elastic and plastic stages of material behaviour of joints and members
Summary
Triangular steel trusses with hollow sections are widely used in bridge and roof structures as truss girders due to their increased spatial stability and decreased material consumption in comparison with the planar trusses (Durfee, 1987; Gao, Bai, Jiang, Wang & HE, 2018). A range of plastic behaviours of connections and cross-sections that the considered structure may demonstrate can be determined in this case. Deformation values and corresponding deflections related to the experimental load-carrying capacity of the structure can be used for structural monitoring, which allows determining the critical level of the load when plastic deformations get irreversible and become uncontrollable. The available values of plastic deformation of structural members and joints related to the experimental load-carrying capacity of the structure can be found only experimentally. Theoretical determination of the available plastic deformation values of the steel structures is currently a topical issue (European Committee for Standardization, 2005). Inverted triangular steel truss with hollow cross-sections taking into account plastic deformations.
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