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

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES 2. At least one intermediate (between column corner bars) vertical bar shall be provided at each side of a joint of primary seismic beams and columns. In the absence of more precise information, the length of the critical region lcr may be computed as follows: Bond Failure lcr = max (hc ; lcl / 6 ; 450 mm) ( 5.41 ) An idealization of the bond failure Vjoint,bf provided by the longitudinal reinforcing bars acting in friction with concrete and embedded in the outer joint region is shown in Figure 5.17. The bond failure occurs in the outer elements if the compression and tension forces (due to moment equilibrium), along with the forces mobilised in the concrete compression field, are greater than the strength of the bond mechanism of a set of main longitudinal re-bars. Figure 5.17. Bond failure mechanism The shear resistance and the moment resistance for bond mechanism is calculated as follows: 1 Vj , b = ⋅ fbd ⋅φb ⋅ xrb, c ( 5.42 ) 1.3 205
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES 206 M = V ⋅ d ( 5.43 ) Rd , j, b j, b s It is assumed that bond failure occurs in the outer elements when the sum of the forces is equal to the bond strength of a set of main reinforcing bars. Tcb + Ttb = Tbf ( 5.44 ) The bond failure strength should be calculated as follows: T = f ⋅φ ⋅ d ( 5.45 ) bf bd b s The design value of the ultimate bond stress fbd for ribbed bars may be taken as: where: η1 2 2/ 3 0.7 ⋅0.3 ⋅ fck fbd = 2.25⋅η1 ⋅η2 ⋅ fctd = 2.25⋅η1 ⋅η2 ⋅ ( 5.46 ) γ is a coefficient related to the quality of the bond condition and the position of the bar during concreting: 1,0 when good conditions are obtained; 0,7 for all other cases and for bars in structural elements built with slip-forms, unless it can be shown that good bond conditions exist; is a coefficient related to the bar diameter φ equal to: 1.0 for φ 32 mm (132 - φ)/100 for φ > 32 mm Where not otherwise indicated in Eurocode 8, for frame systems the beam-to- column joints are required to have an increased moment resistance Mjoint,Rd in order to enhance the ductile capacity of the columns avoiding, in this way, the local formation of plastic hinges. Provided that, at the design stage, the plastic hinge formation in the beams is envisaged, it is necessary in any case to take into account the increase in the beam moment values in order to derive the design joint forces. Focusing the attention on the behaviour of an internal beam-to-column joint belonging to a frame free to deform in plane and subjected both to gravitational c
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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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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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