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

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4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS account inelastic phenomena. The design is such that the joint behaviour is governed by ductile components: the end plate and column flange under bending; the column web panel under shear; and the concrete-slab rebars under tension. More specifically, in the case of hogging moment, the connection is governed by the rebars under tension. In this case, the bond between rebars and concrete limits the yielding between the cracks, so that the total elongation can be evaluated as the sum of the strains of the rebars near the cracks (ECCS-109, 1999). Therefore, the joint rotation results to be ∆ φU = D + D U, S, Tot S R ( 4.24 ) where ∆U,S,Tot is the total elongation capacity of the rebars, Ds is the height of the steel profile and DR the distance between the edge of the upper flange and the centroid of the steel reinforcements. Conversely, in the case of sagging moment, the rotation of the joint is determined by the capacities of the column flange and of the end plate on an experimental basis (Bursi et al., 2002). As a result, the total rotation of the joint reads ∆U, S φU = D + D S C ( 4.25 ) where ∆U,S is the total displacement of the T-stubs, Ds the height of the steel profile and DC the distance between the edge of the upper flange of the steel profile and the centroid of the concrete slab. The joint response is also governed by the deformational capacity of the web panel under shear forces. Thus, in applying the component method in order to account for such rotational capacity, we limited the maximum rotation to 30 mrad. 0.5L δ 0.5L Figure 4.14. Deformed configuration of a sub-frame 121
4. SEISMIC RESPONSE OF PARTIAL-STRENGTH COMPOSITE JOINTS 4.6 Mechanical properties of materials Production standards set strict lower limits for the yield stress, but they leave to the designer nearly complete freedom with regard to the upper limits. European standard ENV 206 (1990) on concrete production does not, for instance, require, on one hand, controls of the maximum resistance, just as in the case of EN 10025 (1993) for structural steels. Eurocode 8 (prEN 1998-1, 2002), on the other hand, recommends that the actual yield stress of steel be such as not to modify the localization of the plastic hinges considered during design. In the case of the beam-to-column joints under study, all the materials were checked preliminarily. The results, reported in Table 4.4, confirm the extremely wide scatter of the resistance values that can, in practice, be obtained. 122 BEAM FLANGE (IPE300 S235) Beam web (IPE300 S235) Column flange (HEB280/260 S235) Column web (HEB280/260 S235) Design yield strength [N/mm 2 ] Measured yield strength [N/mm 2 ] 235 370 235 313 235 341 235 300 End plate (S235) 235 383 Reinforcing bars (B450C) Concrete (class 25/30) Table 4.4. Design and actual yield strength 450 537 25 35 4.7 Seismic performance evaluation for the prototype structure The principal objective of this project is the evaluation of the performance of the composite construction with semi-rigid partial-strength beam-to-column joints and partially encased columns in earthquake-prone regions. Performance is defined in terms of probabilistic performance objectives. A performance objective consists of
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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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4. SEISMIC RESPONSE OF PARTIAL-STRE
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4. SEISMIC RESPONSE OF PARTIAL-STRE
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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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