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

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4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS Some remarks can now be made: • the joints of the interior instrumented frame, where only the web panels reached the elastic limit while no connection yielded at this point, are lower than the exterior ones; • the values of rotation are grater at the first level and on the column line 1. The behaviour of the interior joints was quite elastic and no permanent rotation could be recognized. Conversely, in the exterior frame, all the joints reached the elastic limits. The main plastic mechanism started at about 12 sec, when probably the main inclined cracks on the exterior part of the slab developed. Nevertheless, the behaviour of the structure was essentially elastic and no damage could be observed. 4.10.4 Results of the PsD test n° 3 The objective of the third test was to simulate the Ultimate Limit State, trying to make the joints rotate at least 35 mrad in the plastic range. From a first visual inspection of the beam-to-column joints, so as for the previous test, the damage was located more at the first level on the column line 1 and on the exterior frames. In the beam-to-column joints at Level 1, shear yielding of the web panel at the interior joints was observed, while at the exterior joints, under hogging bending moment, a flexural behaviour of the beam end plates was noticed. After the test, only little permanent deformations could be observed in the steel elements. Figure 4.57. Rupture of the compressed concrete on the interior side of the C1-I joint 165
4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS The shape of the cracks on the slab was quite the same as in test n° 2, even if their extension increased and spalling of the compressed concrete at level 1 was observed, as depicted in Figure 4.57. This last phenomenon was present only on the interior side of the joints. Gaps between the steel column flanges and the concrete slab were also observed at all joints, both the interior and the exterior ones. So as for the previous test, at the column base no damage developed, no cracking and no local instabilities could be observed. Nevertheless, rotation at the base joints under the bending moment transferred by the columns was observed during the test. This was mainly due to the extension of the column anchor rods, and the failure of the grout in compression. Because of the gap between the upper side of the base plate and the nuts, it could be probably stated that yielding of the anchor rods had occurred. After the test, cracking were also noticed in the concrete blocks under the test structure. While processing the experimental results, it was noticed that no beam-to-column joint reached 35 mrad of plastic rotation. In Figure 4.58 the maximum rotations of the joints are shown. +19.9 mrad -3.9 mrad +18.8 mrad -4.5 mrad 166 +30.2 mrad -9.8 mrad +10.3 mrad -5.9 mrad +30.4 mrad -8.4 mrad +11.6 mrad -3.9 mrad +21.5 mrad -23.2 mrad -0.7 mrad -6.6 mrad +22.1 mrad -22.1 mrad -4.3 mrad -4.3 mrad +22.2 mrad -16.6 mrad +26.4 mrad -17.8 mrad +28.7 mrad -16.6 mrad +30.1 mrad -14.9 mrad +6.5 mrad -0.0 mrad +3.7 mrad +2.9 mrad +20.9 mrad -18.3 mrad +5.4 mrad -9.9 mrad +24.0 mrad -19.1 mrad +6.7 mrad -19.0 mrad +15.5 mrad -8.4 mrad +17.3 mrad -0.1 mrad A3 A2 A1 Figure 4.58. Maximum values of rotation reached by the beam-to-column joints of the exterior frame during the PsD test n°3 Other remarks can now be made: • the maximum rotations of the joints at the first and second levels are quite the same; • the joints on the span 1-2 of the interior frame rotated more than the exterior ones, thanks to a higher contribute of the web panels; II I
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Dipartimento di Ingegneria Meccanic
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UNIVERSITÀ DEGLI STUDI DI TRENTO D
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Ai miei genitori
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INDEX 1 INTRODUCTION...............
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INDEX iii 4.10.3 Results of the PsD
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1.1 Introduction 1 1 INTRODUCTION I
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1. INTRODUCTION imposes precise con
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1. INTRODUCTION joints whilst 2D mo
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7 2 DUCTILITY AND SEISMIC RESPONSE
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2. DUCTILITY AND SEISMIC RESPONSE O
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3. SEISMIC BEHAVIOUR OF BOLTED END
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5. SEISMIC BEHAVIOUR OF RC COLUMNS
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6. SUMMARY, CONCLUSIONS AND FUTURE
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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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