Fragility Assessment of a Container Crane under Seismic Excitation Considering Uplift and Derailment Behavior

Abstract

While the container crane is an important part of daily port operations, it has received little attention in comparison with other infrastructures such as buildings and bridges. Crane collapses owing to earthquakes affect the operation of the port and indirectly impact the economy. This study proposes fragility analyses for various damage levels of a container crane, thus enabling the port owner and partners to better understand the seismic vulnerability presented by container cranes. A large number of nonlinear time-history analyses were applied for a three-dimensional (3D) finite element model to quantify the vulnerability of a Korean case-study container crane considering the uplift and derailment behavior. The uncertainty of the demand and capacity of the crane structures were also considered through random variables, i.e., the elastic modulus of members, ground motion profile, and intensity. The results analyzed in the case of the Korean container crane indicated the probability of exceeding the first uplift with or without derailment before the crane reached the structure’s limit states. This implies that under low seismic excitation, the crane may be derailed without any structural damage. However, when the crane reaches the minor damage state, this condition is always coupled with a certain probability of uplift with or without derailment. Furthermore, this study proposes fragility curves developed for different structural periods to enable port stakeholders to assess the risk of their container crane.

Seismic Vulnerability Assessment of Critical Port Infrastructure Components by Modelling the Soil-Wharf-Crane Interaction

“…It is worth mentioning that spectral acceleration at the free surface is also needed according to the model of Kosbab (2010). Referring to the MPS04 model and using 2% exceedance in 50 years, S1.5,2475 was found to be 0.325 g amplified at the soil surface as Fβ S1.5,2475 = 0.625 g. As observed from Figure 12, the damage expected on the cranes calculated according to this study agrees well with the other models with no damage prediction close enough to Kosbab (2010) [27], slight to moderate damage in between Tran et al, (2019) [28] and Kosbab (2010) [27], and heavy damage to collapse similar to that of HAZUS (2004) [18]. It is important to note that analytical fragility functions suggested by Kosbab (2010) [27] and Tran et al, (2019) [28] require an accurate definition of the input motion parameters at the base of the cranes, which is not easy to provide without creating a numerical model.…”

“…Steel yield strength is assigned as 420 MPa. Since detailed data are not available on the cross-section properties of the crane (and its mass), an idealized model was built by accessing the abundance of information (e.g., Kosbab, 2010 [27]; Tran et al, 2019 [28]) through the use of linear beam-column elements. The fundamental period of the sway mode of the crane is considered 1.5 s due to its close similarity with the well-known Californian (Kosbab, 2010 [27]) and Korean (Tran et al, 2019 [28]) jumbo cranes.…”

“…It is noted that the information on the crane configuration is limited due to privacy concerns, hence a nonlinear model was not possible to implement to represent the response of the crane elements. Due to this, two limit states were considered as LS1 dictated by uplifting standing for minor damage, and LS2/LS3 dictated by a representative 2% portal drift representing intermediate to extensive damage (e.g., Kosbab, 2010 [27]; Tran et al, 2019 [28]). Although the distinction between LS2 and LS3 was not achieved in the corresponding fragility curves, the output product is still useful in the immediate aftermath of crane operability, as both LS2 and LS3 define the crane as out-of-use.…”

“…A similar comparison was carried out regarding the fragility models available in the literature for cranes (Figure 12). The latter concerns the fragility curves of HAZUS (2004) [18], those proposed by Kosbab (2010) [27], and the fragility model of Tran et al, (2021) [28]. It is worth mentioning that spectral acceleration at the free surface is also needed according to the model of Kosbab (2010).…”

“…With specific reference to pile-supported wharves, analytical fragility functions based on the outcomes from the numerical analysis were developed by different authors, such as Na et al, (2009) [19], Shafieezadeh (2011) [20], Thomopoulos and Lai (2012) [21], Yang et al, (2012) [5], Mirfattah (2013) [22], Heidary-Torkamani et al, (2013) [23], Bozzoni et al, (2014) [24], Ntritsos (2015) [25], Su et al, (2019) [10], Shah (2020) [3], and Mirzaeefard et al, (2021) [26]. Kosbab (2010) [27] and Tran et al, (2019) [28] proposed analytical fragility curves for container cranes. It turns out that there is a lack of effort in deriving the fragility functions by considering the wharf-crane-soil as a combined system.…”