PSI- Issue 9

I. Shardakov et al. / Procedia Structural Integrity 9 (2018) 207–214 Author name / Structural Integrity Procedia 00 (2018) 000–000

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number of studies on the mechanical properties of the flange connection have been carried out; in particular, the results of tests performed on full-scale samples are described in Prinz et al. (2014). The samples consisting of a column and an adjacent beam were subjected to loading, and a bending moment was applied to the beam until the column-to-beam connection was broken. The size of the flange and the number of connecting bolts varied. Reinforcement of the flange plate using additional stiffeners increases the strength of the connection, but reduces its deformation capacity, Abidelah et al. (2012). The amount of plastic deformation in the reinforced connection decreases and, as a result, the capability of this connection to dissipate vibrations caused by seismic loads decreases. One of the approaches toward improving the stability of the structure under the action of seismic loads implies the reduction of the beam flange width near beam-to-column connections, which increases the deformation capacity of the beam and reduces the loads carried out by the column, Roudsari et al. (2018). A proper analysis for the element with a non-orthogonal beam-to-column joint under seismic loads is given in Hunn et al. (2018). The behavior of a column-to-column bolted joint was explored both theoretically and experimentally taking into account the three-dimensional geometry of the columns, flanges and bolts, Li, He et al. (2018). The dry friction contact conditions were specified for the flanges, and the bolt pretension was taken into consideration. Analysis of the structure, consisting of a large number of beams connected by bolted connections, is presented in Blachowski and Gutkowski (2016). A nonlinear calculation of the construction using the method of subconstructions has been performed, which makes it possible to significantly save the calculation time. The behavior of the structure is modeled when one of the flange connection bolts is removed. In experimental-theoretical work Meng et al. (2018), the influence of the characteristics of the bolted flange column-to-beam connection on progressing breakdown of the structure is investigated. It should be noted that, along with flange connections, welded connections of columns and beams are widely used nowadays. Both in-situ and numerical studies of such connections are carried out Li et al. (2018), Rong et al. (2018) under constant and cyclic loads. Compared to bolted connections, such connections have a number of significant disadvantages. When constructing a structure, the installation of welding connections takes a considerable period of time, requires high qualification of the personnel, and the quality of welded seams can depend on the environmental conditions. The manufacture of flanges for the bolted connection can be performed under stable factory conditions using automated welding lines. Each version of the flange connection has its own peculiarities of the deformation behavior, which become especially significant under inelastic deformation. In the engineering environment, the development and implementation of verified mathematical models that allow analyzing the deformation processes in the elements of flange connections from the elastic state to the complete loss of bearing capacity is an urgent issue. This paper presents a series of experimental and theoretical studies conducted to analyze the specific features of quasistatic deformation processes in bolted flange connections. Mathematical modeling of the stress-strain state of the elements of such connections is complicated by the following three factors: three-dimensional geometry of mating parts, contact interactions between the bolted connections at the stages of their installation and operation, and the availability of large elastoplastic deformations. The first challenge has been overcome through the use of the FEM software, but the remaining two have required the performance of a number of experimental and theoretical studies to provide a reliable mathematical modeling of the stress-strain state in the elements of this joint. 2. Experiment description The schematic drawing of the sample of the flange connection is shown in Fig. 1. The sample consists of a vertical column and two symmetrically located horizontal beams adjacent to it. The horizontal beams are connected to the vertical column by eight bolts. The I-Beam shape of the beam and column is considered. For the experimental study of the deformation processes in the connection elements, a test stand has been developed. The structural diagram of the stand, the load scheme and the system for measuring during the tests are shown in Fig. 2. The sample consisting of a column 3 and a beam 4 is loaded in the power frame 1 using hydraulic jacks 5 connected to the common hydraulic line, which ensures symmetrical loading of the sample throughout the experiment. The figure shows: F, 2F – reaction forces arising, respectively, in the horizontal beams and the column from the action of the jacks; U1, U2, U3 – location of vertical displacement sensors;