Analysis and modelling of the seismic behaviour of high ... - Ingegneria

3. SEISMIC BEHAVIOUR OF BOLTED END PLATE BEAM-TO-COLUMN STEEL JOINTS
Both the 2D and 3D FE analyses account for material non-linearities through
classical plasticity based on the Von Mises yield criterion. Isotropic hardening is
assumed for the analyses. The measured stress-strain properties of the different
materials (column flange, column web, end plate, beam flange, beam web and
bolts) obtained by tensile test were used. Elastic and inelastic convergence studies
have been conducted to evaluate and arrive at the final mesh for the finite element
models. The finite element model was verified by comparing the measured
monotonic and cyclic response of specimens with the predicted monotonic
response (see Figure 3.35). As far as it concerns the cyclic test, the envelope
curve of the experimental tests was found and compared to the curve found using
the finite element model. Experimental data and numerical prediction are in a very
good agreement. The specimen yield strength is well captured as expected;
moreover the numerical simulation captures very well the hardening branch of the
experimental response, both in term of strength and stiffness; this indicates a
satisfactory behaviour of the numerical models. It is important to underline that the
3D numerical model seems to be more efficient by comparison with the
experimental data. This means that the model is able to capture the 3D effects in
terms of stress and strain distribution that have a significant effect on the global
response of the joint.
REACTION FORCE (kN)
175
150
125
100
75
50
25
0
Experemintal
Numerical 2D model
0 25 50 75 100 125 150 175 200
DISPLACEMENT (mm)
REACTION FORCE (kN)
175
150
125
100
75
50
25
0
Experemintal
Numerical 3D model
0 25 50 75 100 125 150 175 200
DISPLACEMENT (mm)
Figure 3.35. Experimental and predicted force vs. displacement of JB1-3 specimen
Moreover, the deformed configuration and the shear stress distribution in the steel
joint can be estimated, for instance, through the plot of Figure 3.36. The 3D model
allows the distribution of shear stresses in the panel zone to be appraised. As a
result, high von Mises stresses approach values in a large zone of the web panel.
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