PSI - Issue 13

I. Shardakov et al. / Procedia Structural Integrity 13 (2018) 1324–1329 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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value of vertical displacements at points U 1 a nd U 3 on the horizontal beams relative to the displacement of the vertical column at point U2 (Fig. 2a):         1 3 2 / 2 U t U t U t U t        , where U 1 (t), U 2 (t), U 3 (t) a re the vertical displacements relative to the reference base at the corresponding point of the structure. The simulation results are shown by the red line, and the experimental data by the blue line.

U 1 (t)

t

Fig. 4. Vertical displacement   U t (mm) vs. time t (min) The value   U t is a macro parameter that integrally reflects all the deformation processes occurring in the vicinity of the bolted connection, including inelasticity and contact interaction. Therefore,   U t can be used as an informative parameter in the deformation monitoring of the flange connection. It follows from the obtained results that the application of the force   150kN F t  to the jacks and its subsequent removal are not accompanied by the return-to-zero of the value   U t due to the elastic behavior of the material, i.e. inelastic deformation begins. Figure 5 shows the time variations of the local deformations (in the horizontal direction) of the vertical column in the vicinity of the bolted connection. These deformations correspond to points E1 and E2 (Fig. 2a) with mounted strain gauges. Red lines refer to the simulation data and blue lines to the experimental data.

a

b

Fig. 5. Deformations 1  (μm / m) at point E1 (a) and 2  (μm / m) at point E2 (b) depending on time t (min) Analysis of the results has indicated that compression, 1 0   , is realized at point E1 and tension, 1 0   , at point E2. It is interesting that the inelastic behavior of the elements in the compressed zone begins at higher loads compared to the stretched zone (at jack forces of 225kN and 190kN, respectively). At the same time, the value of the vertical displacement   U t at which the inelasticty zone starts corresponds to the jack force of ~ 150 kN. This fact can be attributed to the peculiarities of inelastic contact deformations in the bolted joint.