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

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5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES provided by linear analysis conducted in SAP2000 both for the x- and y-direction, giving T1,x = 0.302 sec and T1,y = 0.267 sec. The inertial effects of the seismic action are evaluated through the combination below: Being: ψE i = ϕ ⋅ ψ2 i with Thus: ϕ = Wk = Gk j + ψE I ⋅ Qk j ( 5.6 ) 1,0 for roof 0,8 for other storeys with correlated occupancies ψ2 I = 0,3 for offices and residential buildings I-V Storey ψE 1-5 = 0,24 Roof ψE Roof = 0,3 G1-5= 3561 KN Groof= 2125 KN Q1-5= 1011 KN Qroof= 720 KN W1-5= 3804 KN Wroof= 2341 KN WTot = 5 ⋅ W1-5 + Wroof = 21361 KN is the total weight of the building M = 2177 tons is the total mass of the building Hence, we can derive the total base shear force for each seismic design case and the horizontal seismic forces acting at the different storey heights. The main results of these calculations are reported in Table 5.2. Moreover, in order to cover uncertainties in the location of masses and in the spatial variation of the seismic motion, the calculated centre of mass at each floor i will be displaced from its nominal location by an accidental eccentricity in each direction: e1i = ±0,05 ⋅ Li ( 5.7 ) where e1i is the accidental eccentricity of storey mass i from its nominal location, and Li is the floor-dimension perpendicular to the direction of the seismic action. We obtain e1x equal to 1500 mm and e1y equal to 600 mm. 183
5. SEISMIC BEHAVIOUR OF RC COLUMNS EMBEDDING STEEL PROFILES 184 Design case: LOW DUCTILITY Design case: MEDIUM DUCTILITY Total base shear force = 8716 kN Total base shear force = 3353 kN Floor level Fx (kN) Fy (kN) Floor level Fx (kN) Fy (kN) 1 477.0 477.0 1 180.0 180.0 2 933.0 933.0 2 359.0 359.0 3 1399.0 1399.0 3 539.0 539.0 4 1866.0 1866.0 4 718.0 718.0 5 2332.0 2332.0 5 897.0 897.0 Roof 1722.0 1722.0 Roof 633.0 633.0 Table 5.2. Lateral seismic forces obtained for the two ductility design cases 5.3.3 3D frame modelling After a rough estimation of the geometry of all the structural elements by simplified drafts and schematic diagrams, a simulation of the building behaviour was implemented applying both vertical and horizontal forces to a 3D model drawn by the finite element program SAP2000 (see Figure 5.6). The contribution of a single masonry in-fill was taken into account by an equivalent compression diagonal model endowed the following stiffness: K w 2 cos 0.6 w E ⋅ w⋅ t ⋅ θ = ( 5.8 ) d in which the value 0.6 accounts for the presence of openings, doors, etc. Two different models have been considered: • the first one (see Figure 5.6a) in which the structure was modelled with the masonry in-fill present on each floor of the building (Structure I); • the second one (see Figure 5.6b) in which the structure was modelled without the masonry infill on the first floor. This case, named Pilotis Case (Structure II), was considered with the purpose of maximizing the design action on the base columns and of incrementing the second order effects (inter-storey drift sensitivity). ). In fact, this model implements the aforementioned Soft Storey situation. From these analyses it was found that the most adverse conditions applied to three representative base columns of the building labelled as n° 260, n° 302 and n° 309 (as indicated in Figure 5.4); we also paid particular attention to how the masonry
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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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