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Cone penetration testing on liquefiable layers identification and liquefaction potential evaluation
Published in Michael A. Hicks, Federico Pisanò, Joek Peuchen, Cone Penetration Testing 2018, 2018
E. Anamali, L. Dhimitri, D. Ward, J.J.M. Powell
The response of soils to seismic loading varies with soil type and state, including void ratio, stress history, etc. It is possible to estimate soil type and grain characteristics directly from CPTU results (Lunne et al. 1997) and also an idea of derived fines content, FC. Boulanger & Idriss (2004) correctly distinguished between sand-like and clay-like soils behaviour (Robertson & Cabal, 2015). The soil behaviour type index, Ic for the calculations in this paper is defined using Robertson & Wride (1998) method, which suggests estimating behaviour characteristics using the normalized soil behaviour chart SBTn of Robertson (1990). Robertson & Wride (1998) suggested that the boundary between sand-like and clay-like behaviour is around Ic = 2.60. Furthermore, Robertson (2009) suggested that when Ic≤2.50 soils are assumed to behave as sand-like and when Ic > 2.70 soils behave as clay-like. For values in between, 2.5 < Ic≤2.70, soil behaviour is represented as a transition from predominately sand-like to predominately clay-like (Robertson & Cabal, 2015). Robertson & Wride (1998) suggested zones in which soils are susceptible to liquefaction based on the normalized soil behaviour chart, Robertson (1990), and so the chart was updated showing the zones of potential liquefaction/softening based on CPTU data (Robertson & Cabal, 2015).
Case Study of Seismic Assessment of a Short Irregular Historic Reinforced Concrete Structure: Time-History Vs. Pushover Nonlinear Methods
Published in Journal of Earthquake Engineering, 2023
Antroula Georgiou, Stergos Kotakis, Dimitrios Loukidis, Ioannis Ioannou
Presently, in the European Union, engineers use Eurocode 8, Part 3 to assess the structural capacity of existing structures against seismic loading. The most used method from the ones proposed in the code is the non-linear pushover analysis, since the time-history analysis is found to be too complicated and time-consuming (Bhatt and Bento 2014) and difficult to use its results for retrofit purposes. Yet, the use of the pushover (Nonlinear Static) analysis on existing irregular structures has been studied only by very few authors up until now, e.g. Chopra, Goel, and Chintanapakdee (2004), Fajfar, Marušić, and Peruš (2005), Bhatt and Bento (2014), Carvalho, Bento, and Bhatt (2013). This renders its use for existing reinforced concrete structures with irregularities in plan and elevation problematic. Another parameter of variability is what the different researchers use for determining the actual seismic demands. Bhatt and Bento (2014) compared four different non-linear static procedures, i.e. 1) Capacity Spectrum Method- CSM-FEMA440, 2) N2 method proposed in the Eurocode 8 (CEN 2004, 3) Modal Pushover Analysis (Chopra and Goel 2002; Chopra, Goel, and Chintanapakdee 2004), and 4) Adaptive Capacity Spectrum Method (Casarotti and Pinho 2007), considering only three real records in the two planar directions (without using a vertical time-history). It is found that the modal load pattern results in lower values of base shear than the uniform load pattern and the adaptive capacity spectrum method, while in terms of displacement, all the static analyses presented led to higher values than the time-history results, assuming that the Eurocode N2 and CSM-FEMA440 lead to more conservative predictions.
Linear equivalent seismic response of a surface foundation excited by an SH harmonic wave
Published in European Journal of Environmental and Civil Engineering, 2022
Hamoudi Belkhir, Badreddine Sbartai, Kamel Filali, Salah Messioud
In this study, we used the Caldynasoil code to find the variations in the dynamic properties of the soil material according to different levels of deformation due to imposed seismic excitation. This method is based on the discretisation of the soil in horizontal sub-layers with a different modulus of shear and damping. After calculation, each sub-layer of soil will contain variations of the dynamic properties of the material compatible with the deformation imposed by the seismic loading.