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

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES For a single-sided joint, or a double-sided joint in which the beam depths are similar, the design shear resistance of concrete encasement into the column web panel depends by the following geometrical and mechanical parameters: ( ) θ ( ) A = 0.8⋅ h − 2⋅ t ⋅cos ⋅ b − t ( 5.26 ) c c cf cf cw Nsd ν = 0.55⋅ 1+ 2⋅ ≤ 1.1 ( 5.27 ) N pl, Rd h 2 1 c − ⋅t − cf θ = tan ( 5.28 ) z For connections with contact plates, the center of compression should be assumed to be in line with the mid-thickness of the compression flange. For connections with contact plates and only one row of reinforcement active in tension, the lever arm z should be taken as the distance from the center of compression to the row of reinforcement in tension. For connections with contact plates and two rows of reinforcements active in tension the lever arm z should be taken as the distance from the center of compression to a midway point between these two rows, provided that the two rows have the same cross-sectional area. In the formulation above, ν is a multiplier factor which accounts for the column axial load effects on the joint shear resistance, following the prescriptions of Eurocode 2. Bearing Failure The horizontal bearing strength Vjoint,hb is determined through a standard Stress Block model similar to that used for flexural strength calculation in reinforced concrete members. The shear resistance and the moment resistance for the concrete compression strut are calculated as follows: 1 f V = ⋅ 0.85⋅ ⋅a ⋅ b ( 5.29 ) j, hb 1.3 ck , c γ c c cf ( ) M = V ⋅ h − a ( 5.30 ) Rd , j, hb j, hb b c To evaluate this resistance it is of primary importance to be able to guarantee an adequate concrete confinement inserting a proper ties quantitative which enhances the concrete performance. Confinement of concrete results in a modification of the effective stress-strain relationship: higher strength and higher critical strains are 201
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES achieved (Mander, 1988). The other basic material characteristics may be considered as unaffected for design. In the absence of more precise data, the stress-strain relation with increased characteristic strength and strains may be used, according to: 202 f f σ 2 ck , c = ck ⋅ 1+ 5⋅ if 2 0.05 · fck ( 5.31 ) fck f f σ 2 ck , c = ck ⋅ 1.125 + 2.5⋅ if 2 > 0.05 · fck ( 5.32 ) fck where 2 (= 3) is the effective lateral compressive stress at the ULS due to confinement. The value ac is the stress block depth equal to 0.58 hb/2. 5.4.2 Strength of the Outer Elements Shear Failure The concrete compression field mechanism, shown in Figure 5.16, consists of several compression struts that act with horizontal reinforcement to form a truss mechanism (often used for modelling shear in reinforced concrete beams). Shear is transferred horizontally from the beam into the compression field through bearing against the embedded steel column. Figure 5.16. Concrete compression field mechanism
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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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Analysis and modelling of the seismic behaviour of high ... - Ingegneria

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