PSI - Issue 62

Carlo Pettorruso et al. / Procedia Structural Integrity 62 (2024) 677–684 Carlo Pettorruso/ Structural Integrity Procedia 00 (2019) 000 – 000

682

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Table 1 Deck loads G 1

Self-weight

168,3

kN/m kN/m kN/m

G 21 G 22

Nonstructural loads 1 Nonstructural loads 2

42

5

G deck Q 0,2

Deck weight

7535,5

kN kN

20% of traffic loads

438

Figure 5. V beams deck

A parametric investigation is performed by considering piers of different height H (5 m, 10 m, 20 m) and different seismic scenarios. 3.1. Piers characteristics Parametric analysis is performed accounting the circular RC piers; as the height of the pier varies, the longitudinal rebar is changed accordingly, while the gross cross section is kept unchanged. Volumetric ratios of ρ s =0,4% and ρ w =0,09% (defined as the volume of longitudinal bars divided by the volume of concrete, and the volume of stirrups divided by the volume of confined concrete) are assumed for the longitudinal and the transverse reinforcement of the 5 m high pier (Delgado 2009, Pinto 2003). For the 10 m and the 20 m high piers, the volumetric ratio counts ρ s =0,7% and ρ s =1%, re spectively; the transverse volumetric ratio is equal to ρ w =0,09% and is independent of the pier height. C25/30 concrete is assumed, with a Young's modulus E c = 31475,8 MPa and a characteristic cylindrical strength f ck = 25MPa; steel for the rebar is FeB44k, with Young's modulus E s = 200GPa, characteristic yield strength f yk = 430 MPa and characteristic tensile strength at break f tk = 540MPa. A 2 m diameter pier is considered, with longitudinal reinforcement arranged radially and consisting of 24φ26 bars for the 5 m high pier, 32φ30 bars for the 10 m high pier, and 44φ26 bars for the 20 m high pier. The transverse

reinforcement in all cases consists of circular φ16 stirrups spaced with 15 cm pitch. Sectional characteristics related to reinforcement for the piers are given in Table 2.

Table 2 Reinforcement characteristics

H=5 m

H=10 m

H=20 m

Number of rebar Rebar diameter

n l φ

[-]

24 26

32 30

44 30

mm

n w

Number of stirrups for meter

[-]

13,33

13,33

13,33

Stirrup’s diameter

φ

mm

16

16

16

A s

m 2

Longitudinal steel area Transversal steel area

0,0127 0,0027 0,40% 0,09%

0,0226 0,0027 0,70% 0,09%

0,0311 0,0027 0,99% 0,09%

m

A w

2

Longitudinal volumetric ratio Transversal volumetric ratio

ρ s ρ w

[-] [-]

3.2. Seismic scenarios Three scenarios were defined according to IBC, assuming a design life VN = 50 years and use class IV (cu = 2.0) (NTC 2018, § 2.4.3), to which the reference periods are related (NTC 2018, § 3.2.1). The three seismic scenarios correspond to seismic zones 1, 2 and 3 according to the Italian Building Code. The code classifies the entire Italian