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Earthquake Effects on Buildings
Published in Bungale S. Taranath, Tall Building Design, 2016
The acceleration experienced by a building will vary depending on the period of the building, and in general, short-period buildings will experience more accelerations than long-period buildings. The USGS maps recognize this phenomenon by providing acceleration values for periods of 0.2 s (short) and 1.0 s (long). These are referred to as spectral acceleration, and the values are approximately what are experienced by a building (as distinct from the peak acceleration that is experienced at the ground). The spectral acceleration is usually considerably more than the peak ground accelerations.
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Published in A. Ghali, A. M. Neville, Structural Analysis: A unified classical and matrix approach, 2017
Time-stepping analysis of acceleration record of a real earthquake can be used to derive graphs of pseudo-acceleration and pseudo-velocity versus natural period of vibration, T of single-degree-of-freedom systems. Such graphs, when done for several earthquake records expected for a site, can be used to prepare spectral acceleration graphs to be used to determine the loading in seismic design of new structures. More sophisticated techniques are required in certain codes.
The Ghirlandina Tower in Modena: An example of dynamic identification
Published in Renato Lancellotta, Alessandro Flora, Carlo Viggiani, Geotechnics and Heritage: Historic Towers, 2017
The preservation of cultural heritage requires a careful assessment of the necessary remedial measures. It is indeed essential to preserve not only the shape and appearance of a monument but also its historical and material integrity. In this context, the construction techniques, the materials, and the structural scheme need to be considered within a multidisciplinary approach. A patient attitude is necessary to devise the stabilizing measures only after the behavior of the monument is properly understood. In particular, assessing seismic vulnerability and long-term behavior of historical towers requires modeling the interaction of the structure with the supporting soil, because soil-structure interaction strongly affects the seismic capacity of the system, related to soil strength, as well as the seismic demand (Di Tommaso et al., 2013). In the latter case, depending on the soil stiffness, the fundamental period of the structure will increase, with a corresponding reduced spectral acceleration. This reduction, combined with energy dissipation mechanisms, give reason for the good performance of the Ghirlandina tower during past seismic events (1501, Castelvetro; 1505, Bologna; 1671, Rubiera; 1832, Reggio Emilia; 1996, Correggio), despite the damage suffered by the Cathedral.Experimental identification analyses performed under ambient vibration excitation provide a sound validation of theoretical approaches suggested in literature to estimate the dynamic stiffness of a soil-foundation system. However, considering the very low strain level involved in both identification analysis and shear wave propagation during cross-hole tests, the obtained values of the soil-foundation stiffness is appropriate only for low intensity seismic motions. Further considerations need to be introduced when dealing with strong motions in order to account for the non-linear soil behavior. Therefore, a value of G consistent with the shear strain level computed from a seismic site response analysis should be used.The above conclusion applies to the present case, since it has been validated by means of a continuous monitoring system. This aspect deserves special attention because, as it was shown, monitoring increases the capability to detect the importance of non-linear phenomena as well as possible damage that could occur in the long term performance of the structure, subjected to repeated seismic events.
Probabilistic Fling Hazard Map of India and Adjoined Regions
Published in Journal of Earthquake Engineering, 2022
J. Dhanya, S. T. G. Raghukanth
Typically, we carry out the seismic hazard analysis for spectral acceleration (Sa). However, recent studies have identified the importance of considering hazard associated with other components of ground motion like peak ground velocity (PGV) and peak ground displacement (PGD) (Muthuganeisan 2017; Parvez, Vaccari, and Panza 2003; Petersen et al. 2011). These estimations find their application in the displacement-based design of structures. Another important aspect that is not addressed to date is the hazard due to fling, which corresponds to the permanent ground residual displacement during an earthquake. Fling is critical as it can severely damage lifeline structures such as pipelines, roadways, dams, tunnels, etc. which pass through a fault or those constructions that are right above the fault plane. Additionally, fling in ground motion would enhance the seismic demand of nonlinear structures (Chopra and Chintanapakdee 2001; Dhankot and Soni 2017; Huang 2015; Kalkan and Kunnath 2006; Nicknam et al. 2014; Shahbazi et al. 2019; Wu et al. 2014).
Assessment of the Seismicity of Peshawar Region in Line with the Historical Data and Modern Building Codes (ASCE-07 & IBC-2006)
Published in Journal of Earthquake Engineering, 2021
Bilal Ahmad Shah, Muhammad Maqbool Sadiq, Shazim Ali Memon, Sardar Kashif Ur Rehman
The BCP defines seismic loading for structures in terms of PGA. However, PGA alone cannot estimate the damage potential of an earthquake accurately [Norsar, 2007]. For example, many earthquakes of same PGA possess different amount of energy, have different duration of shaking, frequency content etc. traditionally the PGA values are adopted for the estimation of seismic hazard because of its easy computation from the accelerograms. Due to such limitations modern building codes define seismic loading in terms of spectral ordinates. For example, IBC 2006/09 and ASCE-07 defines seismic loading in terms of spectral acceleration values for a structural period of 0.2s and 1.0s. However, in this research, the spectral acceleration values were calculated at a structural period of 0.1, 0.2, 0.5, 0.8, 1.0, and 1.5s in units of m/s2. The intermediate values of structural period were selected so as to obtain a uniform hazard curve. Calculation of spectral acceleration values will allow the structural engineers, the utility of modern building codes for the estimation of seismic loading.
Susceptibility modelling of seismically induced effects (landslides and rock falls) integrated to rapid scoring procedures for bridges using GIS tools for the Lowlands of the Saint-Lawrence Valley
Published in Geomatics, Natural Hazards and Risk, 2018
Azarm Farzam, Marie-José Nollet, Amar Khaled
The New York State Department of Transportation (NYSDOT 2002) classifies the New York's regular bridges from 0 to 100 according to the seismic hazard and their seismic structural vulnerabilities which includes the vulnerability to abutment failures. Seismic hazard was related to the seismic zone defined according to spectral acceleration values. Kim (1993) developed a GIS-based regional risk analysis approach for bridges against seismic hazards, defined from the PGA, considering liquefaction but not landslides as site condition effects induced by earthquake. Moreover, no other ground failure is included in the final application due to the lack of data. In France, the Direction des Routes et le Service d’Études Techniques des Routes et Autoroutes uses the SISMOA method as a preliminary evaluation procedure of seismic risk of bridges (Davi et al. 2011). It is one of the few methods that include liquefaction, landslides and rock falls hazards. Each of these induced effects is computed independently depending on the structural characteristic of the bridge (vulnerability to the induced effect) and its hazard. The latter is a relationship between the critical ground acceleration necessary to induce landslides, rock falls or liquefactions. SISMOA approach can be used as reference for the attribution of vulnerability indices to bridge structures towards different induced effects.