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

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES different in term of dissipated energy; this means that only the portion of the steel profile in the web panel zone behaves in an inelastic range, whereas the other portion of the column behaves elastically, with a little contribution to the absorbed energy. This difference has been summarized in the following Table 5.15. ACCUMULATED ENERGY (kJ) 700000 600000 500000 400000 300000 200000 100000 0 RCT5 COT9 COT10 COT11 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 DISTORTION γ (mrad) Figure 5.38. Comparison in term of accumulated energy for the tested specimens IMPOSED DISPLACEMENT 2e + y 4e + y 6e + y 8e + y ACCUMULATED ENERGY (KJ) RCT5 COT10 COT11 e + y 1244 1075 1135 1° cycle 2° cycle 3° cycle 1° cycle 2° cycle 3° cycle 1° cycle 2° cycle 3° cycle 1° cycle 2° cycle 3° cycle 3089 4705 5910 10612 15312 19008 24873 34685 43604 / 2592 3891 4815 8795 14477 19282 26432 38249 49249 61747 82533 102310 2882 4908 6564 11355 19173 26032 34778 49915 64246 80811 105833 129912 DIFFERENCE OF THE ACCUMULATED ENERGY (%) COT10 − RCT 5 COT11− RCT 5 RCT 5 RCT 5 -16,1 -17,3 -18,5 -17,1 -5,5 1,4 6,3 10,3 12,9 -6,7 4,3 11,1 7,0 25,2 37,0 39,8 43,9 47,3 / / Table 5.15. Comparison in term of cumulated energy for the tested specimens 229
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES Summarizing, we can say that the tests conducted on specimens COT9 and COT10 confirm to have a very similar behaviour regardless of the presence of the continuity plates. Both samples reached or nearly reached the conventional end of test. The important piece of information for COT11 and COT12 mostly concerns the type of failures occurred to these specimens. Hence, we have to judge whether the displacement level reached for the specimens belonging to the C3 configuration (normally 8ey) establish a sufficient amount of ductility or it simply shift the problem from the joint to another cross column section (the weakest one). In fact, the connection panel with short profile encased, showed a good resistance. Nonetheless, it may cause the brittle failure of the column before the requested time, necessary to resist a seismic event. 5.7 Numerical analyses and validation of the mechanisms In this section, the inelastic finite element (FE) analyses carried out by means of the ABAQUS code (2003) are discussed. Thereby, the FE models were calibrated and the stress and strain state of the aforementioned joints was simulated in the monotonic displacement regime. Finally, by means of the analysis results a validation of the proposed analytical formulas have been determined. The modification in the dimension of some geometrical and mechanical parameters, obtained through the elaboration of the numerical evidences, has permitted to match better the experimental resistance of the joint subjected to shear loads. 5.7.1 FE Model of the specimens Non-linear FE analyses of the tested specimens were carried out in a monotonic loading regime. The analyses have been developed with 3D FE models. The used model is reported in Figure 5.39 and represents the specimen COT9, endowed with an HEB 140 steel profile. It is characterized by reduced integration eight-node solid elements (C3D8R in the ABAQUS library). The 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 new model Concrete in ABAQUS code has been used. This model permits to define the correct strain-stress curve of the concrete both in tension and in the compression. Moreover, for cyclic loading history, it is possible to define a degradation law for the stiffness characteristics. The measured stress-strain properties of the different materials (column flange, column web, stiffeners, rebars in the beam and in the 230
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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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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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