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Seismic Design of Large-scale Cut and Cover Tunnel
Published in T. Adachi, K. Tateyama, M. Kimura, Modern Tunneling Science and Technology, 2020
Y. Adachi, Y. Fujii, H. Ishizaki
At first, the tunnel is conventionally designed against permanent load, such as dead weight, overburden, soil pressure, water pressure, and so on. No seismic effect is considered for the base design. The seismic analysis is performed to check whether the structure that is conventionally designed has enough seismic resistant capacity or not against moderate earthquake or intensive earthquake.
Reliability-Based Design for Structures
Published in Mohamed Abdallah El-Reedy, Assessment, Evaluation, and Repair of Concrete, Steel, and Offshore Structures, 2018
Reliability Analysis of Structures Considering Uncertainty of Ground Input. The simplest analysis that can be performed is that of finding the seismic reliability of a structure using a risk consistent spectrum (or uniform hazard spectrum) that considers the uncertainty of ground motion input only. The probability of failure of the structure designed with this spectrum is the exceedance probability of the response spectrum ordinate being used for the design. If a uniform hazard spectrum or risk consistent response spectrum is constructed using seismic hazard analysis, then it is implicit that the analysis also considers uncertainties (2) and (1). Thus, if a rigorous seismic hazard analysis has been performed for a site and the resulting seismic input in the form of a risk consistent spectrum is used in the seismic analysis of the structures, then the uncertainties indicated in (1), (2), and (3a) are mostly included in the reliability estimate. Note that the estimated probability of failure does not include other uncertainties as discussed above and that the failure of the structure is assumed to take place under the load, determined from the spectrum.
Seismic Code Provisions
Published in Hector Estrada, Luke S. Lee, Introduction to Earthquake Engineering, 2017
As discussed in Section 8.4.2, earthquake loads can be obtained using an equivalent static method (as presented here) or a full dynamic analysis approach presented in the following sections. The main purpose of any seismic analysis is to ensure that strength and lateral deflection (drift) requirements are satisfied. ASCE-7 ELFP is similar to the generalized SDOF system analysis for shear buildings presented in Chapter 6. The process involves determining the natural period, the base shear, equivalent static story forces, story drifts, and overturning moment.
Seismic Analysis of the Vacuum Vessel for CFETR
Published in Fusion Science and Technology, 2022
Xiaojun Ni, Songbo Han, Jian Ge, Jinxin Sun
A seismic event as the most demanding loading condition may also threaten structural integrity.5,6 The CFETR VV shall be capable of withstanding seismic activity according to the design requirement. Therefore, it is necessary to carry out seismic analysis to assess structural behavior against seismic loads. The purpose of this study is to investigate the effects of typical seismic loads on the CFETR VV. In this paper, the seismic response of the CFETR VV is investigated by finite element method (FEM) analyses following two approaches. One is equivalent static (ES) analysis as a static approach, which simply calculates the structural behavior under the peak acceleration value obtained from the design response spectrum. The other approach is response spectrum (RS) analysis, which is a dynamic approach. In RS analysis, modal analysis as an input is initially carried out to uncouple the total dynamic response for the structure into a number of individual modes, and multiple modes of response are considered for the structure. Finally, the analysis results from the foregoing two approaches are described, compared, and summarized.
Damping Modification Factors Observed from the Indian Strong-motion Database
Published in Journal of Earthquake Engineering, 2021
Mitesh Surana, Yogendra Singh, Dominik H. Lang
In earthquake engineering, the majority of seismic analysis and design methods rely upon the response spectrum. Almost all national seismic design codes [e.g. ASCE 7-10 2010; CEN 2004; EN 1998 2004; IS 1893 Part 1: 2002] provide site class-dependent elastic response spectra which correspond to a viscous damping ratio of 5%. Damping modification factors (DMFs) (as illustrated in Figure 1) are further provided to convert the 5% damped elastic response spectrum to a response spectrum for any other desired damping ratio. The design response spectra corresponding to lower or greater damping ratios are often used in performance-based seismic design of structures, e.g. highly damped spectra for direct-displacement-based seismic design, estimation of target displacement when using the ‘Capacity Spectrum Method,’ seismic design of energy-dissipating devices, or isolation systems, whereas low-damping spectra are used in ‘seismic design of non-structural components’.
MASTODON: An Open-Source Software for Seismic Analysis and Risk Assessment of Critical Infrastructure
Published in Nuclear Technology, 2021
Swetha Veeraraghavan, Chandrakanth Bolisetti, Andrew Slaughter, Justin Coleman, Somayajulu Dhulipala, William Hoffman, Kyungtae Kim, Efe Kurt, Robert Spears, Lynn Munday
Seismic analysis involves the calculation of seismic loads on the systems, structures, and components (SSCs) of a facility and is a key part of seismic design and risk assessment. Safety-critical facilities, such as hospitals, dams, nuclear power plants (NPPs), and facilities handling radioactive materials, must meet certain seismic safety standards that are typically expressed as an upper limit on the seismic risk. Seismic analysis and risk assessment at these facilities is therefore necessary during their design and also through their life span. The seismic risk at a safety-critical facility depends on the surrounding earthquake faults and site characteristics that determine the seismic hazards on the SSCs of the facility and the possible accident sequences. The SSCs and the accident sequences together dictate the vulnerability of the facility to a given seismic hazard. Due to the large variability in local site properties and seismic hazards, when a similar structure is constructed at various sites (such as a specific NPP design), it must be designed and assessed for each site.