Abstract
Ship-to-shore (STS) container gantry cranes, used at terminals for loading and unloading containers from a ship, are an important part of harbor structures. The size and weight of modern STS container cranes are increasing to satisfy the demand for bigger ships. This is expected to result in more lateral load when excited by seismic motions. The existing Korean STS container cranes did not behave properly during several recent moderate earthquakes in South Korea. Typical Korean STS container cranes must be checked for the earthquake-resistant capacity. In this research, two nonlinear static analyses procedures, also known as pushover analyses, commonly used for seismic design of buildings, namely, capacity spectrum method and equivalent linearization method, are comprehensively studied to check their suitability for studying seismic behavior of STS cranes. Results obtained by these two nonlinear static analysis methods are then compared with the results obtained by nonlinear time-history analyses of the STS cranes by exciting them with nine recorded earthquake time histories around worldwide. The behaviors of the cranes are analyzed in terms of the total base shear, drift, and base uplift. The comparisons indicate that the nonlinear static methods can be appropriate for estimating the total base shear and drift of the portal frame of a container crane. The pushover analyses also provide information on performance levels as defined in ASCE/SEI 41-13, of a typical Korean STS container crane. Furthermore, it is observed that the uplift response of the crane is strongly influenced by the duration of an earthquake.
Highlights
Nonlinear static analysis (NSA), known as pushover analysis (PA), is an effective tool for performance assessment of a structure under a seismic event
Some of the concepts officially incorporated in design guidelines include capacity spectrum method (CSM) and displacement coefficient method (DCM) as adopted in ATC-40 [2] and ASCE-41 [3], N2 method as proposed in Eurocode 8 [4], and equivalent linearization method (ELM) and displacement modification method (DMM) as presented in FEMA 440 [5]
A three-dimensional (3D) finite element (FE) model generated by SAP2000 is analyzed first by CSM and ELM. e results of these NSA methods are verified by exciting the crane by nine scaled recorded ground motion time histories. e results obtained by CSM and ELM were compared with the more comprehensive and accurate nonlinear time-history analysis (THA). e primary objective of this study is to investigate whether commonly used NSA methods developed for the seismic design of buildings can be used for a STS container crane
Summary
Nonlinear static analysis (NSA), known as pushover analysis (PA), is an effective tool for performance assessment of a structure under a seismic event It requires less calculation than nonlinear dynamic analysis and avoids using a set of ground motion time histories [1]. E overall steps of the NSA method include the selection of load patterns, nonlinear analysis of the structure to obtain the capacity curve, calculation of displacement demand using a response spectrum, and the assessment of the performance of the structure [1]. Ey are selected because they provide a graphical relationship between the capacity of a structure and the seismic demand, and it is relatively easy for engineers to estimate the maximum displacement by using them These methods are recommended in many design guidelines and standards worldwide. The uplift response, base shear, and drift are addressed and compared in this study
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
