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

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES guaranteed by tests carried out at the ProfilArbed laboratories. For an economical design of the steel members we considered this upper limit. The elastic modulus E is to be 210000 MPa. 5.3.2 Load combinations In the present paragraph a base column of a five-storey building is designed for each of the three different load combinations listed below: 1. Gravity Load Combination, designing the columns only according to Eurocode 2. q1= Σ1(γG GK,i)+γQ⋅QK,1+Σ2(γQ ψ0QK,i) ( 5.1 ) 2. Seismic Load Combination A, assuming the structural elements in the Low Ductility Class designing the columns only according to Eurocode 2. q2= Σ1(GK,i)+AE,d+Σ1(ψ2QK,i) ( 5.2 ) 3. Seismic Load Combination B, assuming the structural elements in the Medium Ductility Class, and for that reason designing the columns according to Eurocode 2 and Eurocode 8. where: GK,i QK,1 QK,2 AE,d q3= Σ1(GK,i)+AE,d+Σ1(ψ2QK,i) ( 5.3 ) is the dead load is the imposed live load is the wind load is the horizontal seismic action: EEdx+0,3 EEdy. γG Unfavourable γQ Unfavourable ψ0 ψ2 γG Favourable γQ Favourable 1.35 1.5 0.7 0.3 1 0 Table 5.1. Values of the coefficients for the load combinations The uniformly distributed loads to be vertically applied to the structural members have been calculated from the combinations above assuming typical values, found 181
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES in the design tables, for what concerns the material specific weights. A uniformly distributed live load of 3.0 kPa was assumed at each storey level (mechanical equipments, finishes, etc.). Different values of the dead and live loads were calculated for the roof; in this case the live load is equal to 2.0kPa. Subsequently, the horizontal seismic forces acting at each storey height according to Eurocode 8 have been determined; being the structure regular both in plan and in height (prEN 1998-1, 2001), it is allowed to carry out a simplified planar static analysis, the so-called Lateral Force Method Analysis. The equivalent horizontal seismic forces, represented as nodal forces acting at each storey height, have been determined for the seismic study cases denominated above as A and B. For the two load combinations we assumed the same peak ground acceleration, i.e. 0.20g, which implies that the construction site belongs to a low seismicity area. Only the main aspects that are relevant to the seismic resistance of the moment resisting frames in the direction of loading are summarised herein. The design seismic loads at each level, Fi, were determined using the simplified modal response spectrum analysis method: 182 F = F ⋅ i b z ⋅ m i i i ( z ⋅ m ) i i ( 5.4 ) where Fb is the seismic base shear, and zi and mi are respectively the height from the ground level and the masses at each storey of the building. The seismic base shear force is given by: F = S ( T ) ⋅W ⋅ λ ( 5.5 ) b d 1 where Sd(T1) is the ordinate of the design spectrum at the fundamental period of vibration of the structure for translational motion in the direction considered, T1, W is the total weight of the building, and is a correction factor. The equations and the values of the soil parameter, S, and the reference periods TB, TC, and TD that are required to construct Types 1 and 2 design spectra are given below. For this project, the following key parameters were adopted: • Type 1 spectrum; • Peak ground acceleration, ag = 0.20 g; • Subsoil Class A (Rock site, or alike, with Vs,30 > 800 m/s); • Behaviour factor, q = 1.5 for Ductility Class LOW and q = 3.9 for Ductility Class MEDIUM. Therefore, S = 1.0 and the reference periods TB, TC, and TD are respectively equal to 0.15 sec, 0.5 sec, and 2.0 sec. The fundamental period T1 of the structure was
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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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