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Chapter 8/Seismic response of buildings
Published in Ajaya Kumar Gupta, W J Hall, Response Spectrum Method, 2017
The UBC has five zones, the highest being seismic Zone 4 and the lowest Zone 0. The latter has no seismic design requirement. For Zones 4–1, the values of Z are 1, 3/4, 3/8 and 3/16, respectively. There are three categories based on the importance of the building. For essential facilities the importance factor, I, is 1.5, for large occupancy buildings it is 1.25, and for all other buildings, 1.0. The building coefficient, K, depends on the type of structure, ranging in value from 2/3 to 4/3 for buildings and on up to 2.5 for elevated tanks. The K-factor, in effect, lowers the margin of reserve strength required for structural systems that have performed well in past earthquakes and raises the margin for systems that have performed poorly. The site-structure resonance factor is a function of the ratio of the building period to the site period and varies between 1 and 1.5. If the site period is not available, a factor of 1.5 must be used. However, the value of the product CS need not exceed 0.14. The UBC is intended to be used with the working stress design method. The code allows a 1/3 increase in the allowable stresses. Conversely, the seismic loads can be multiplied by a factor of 3/4.
Structural vibration control
Published in You-Lin Xu, Jia He, Smart Civil Structures, 2017
Major sources of microvibration, affecting the normal operation of high-tech equipment, are due to traffic-induced ground motion, service machinery-induced floor vibration and direct disturbance caused by production-related activities in the form of a suddenly applied load (Ungar et al. 1990). Several well-known families of generic vibration criteria are in use for microvibration control of high-tech equipment in terms of velocity, such as the Bolt, Beranek and Newman (BBN) vibration criteria (Gordon 1991). Compared with traffic-induced ground motions, earthquake-induced ground motions are of relatively low frequency range but very high intensity. The building structures themselves in seismic zones are generally designed to meet seismic code requirements. However, fragile and vibration sensitive equipment is often mounted on the building floor without considering seismic provisions making it extremely vulnerable to a seismic-induced lateral load. Under a performance-based design concept, it is now recognised that high-tech equipment must function immediately after an earthquake and therefore seismic protection for high-tech equipment is urgently needed (Amick and Bayat 1998). Although there are no consensual seismic design criteria for high-tech equipment, it is believed that excessive acceleration responses lead to damage to high-tech equipment.
Siting in relation to exceptional environmental events: earthquakes and faults, tornadoes, tsunamis and floods
Published in Peter R. Mounfield, World Nuclear Power, 2017
The whole of the Californian coast, together with much of the inland part of the state, lies in an area designated seismic zone 3, a zone where major damage is possible from seismic activity (see Figure 11.1). Thus the major part of the Malibu Hearings was devoted to consideration of the geology and seismicity pertinent to the reactor site, especially ground acceleration or shaking, and permanent ground displacement or rupture.
The effect of ductility on the seismic collapse risk of residential steel moment-resisting frames at Alborz and Zagros Seismic zones, Iran
Published in Sustainable and Resilient Infrastructure, 2022
Ali Jafari, Elham Rajabi, Gholamreza Ghodrati Amiri, Seyed Ali Razavian Amrei
A seismic zone is an area with a potential seismicity sharing a common cause and a common rate of seismicity that is assumed for the purpose of calculating probabilistic ground motions. Active faults and volcanic high surface elevations along Himalayan-Alpide earthquake belt characterize the Iranian plateau. According to the earthquake data of Iran, most activities are concentrated along Zagros fold thrust belt in comparison to the central and eastern parts of Iran. Thus, several regions are vulnerable to destructive earthquakes. Several studies have been done on the seismotectonic structure of Iran in the past. Stocklin (1968), Takin (1972), and Berberian (1976) have suggested simplified divisions consisting of nine, four, and four regions, respectively. A more elaborated division consisting of 23 seismotectonic provinces was suggested by Nowroozi (1976). Tavakoli (1996) proposed a new model for seismotectonic provinces using a modified and updated catalog of large and catastrophic Iranian earthquakes and has divided Iran into 20 seismotectonic provinces. In this study, seismic zoning proposed by Ghodrati Amiri et al. (2007) is adopted, categorizing Iran in two regions of Zagros, and Alborz and Central Iran. The city of Tehran is located on the southern slope of the Alborz Mountain range and the city of Hamedan is located on the slopes of the Alvand Mountain in the eastern part of the Central Zagros.
A preliminary study of wind–solar hybrid systems potential in Jammu and Kashmir
Published in International Journal of Ambient Energy, 2020
Pramod Kumar Sharma, Siraj Ahmed, Vilas Warudkar
Overall, the preliminary study of Jammu and Kashmir region indicates the availability of a huge potential for commercial combined solar–wind development subjected to some restriction. The following conclusion can be drawn from the literature survey: Four districts (LEH, KARGIL, POONCH and REASI) are suitable for small wind–solar hybrid systems.BIDDA (REASI) and CHUSHUL (LEH) are the two sites for small wind farm development due to highest wind speed (more than 7 m/s) and power density (more than 400 W/m2) at 100 m agl.Three types of wind–solar hybrid systems with a capacity of 1.5, 5 and 10 kW can be installed at the sites mentioned in Table 4.The seismic moments need to be studied properly. The region has major seismic activities; several seismic zones have been identified in earlier studies associated with known geological structural and fault zones.
Stress-history impact on yielding, shear and energy dissipation response of earthen dam soil under static and cyclic loading conditions
Published in Geomechanics and Geoengineering, 2023
Naman Kantesaria, Tanaya Mukati, Ajanta Sachan
Geological phenomena such as tectonic activities, erosion, deposition, change in the water table and frequent loading and unloading due to the constructional activities and excavation render drastic modifications in the geotechnical properties of the soil deposits due to the generation of stress history. As the normally consolidated (NC) state gets transformed into an overconsolidated state, the soil structure configuration, shear strength behaviour and volume change tendencies get altered considerably. Any soil deposit in the natural state may occur in the loosest to densest state, depending upon the geological events. As the soil fabric transitions from a loose to a denser state, the strength and stiffness of the soil skeleton get enhanced and so does the shear behaviour and stability characteristics (Tatsuoka et al. 1986, Igwe et al. 2012). Moreover, soil subjected to different loading conditions exhibits different shear responses and strength degradation mechanisms. The soil deposits reveal distinct static behaviour, cyclic shear behaviour and failure modes when exposed to static and cyclic loading conditions. These studies become more indispensable for the civil engineering structures being constructed in seismically active regions from a stability and serviceability point of view. Studies on past major earthquakes like 1971 San Fernando, 1995 Kobe and 2001 Bhuj have reported the occurrence of liquefaction during the seismic shaking (Tuttle et al. 2002, Yuan et al. 2004, Singh et al. 2005). The occurrence of liquefaction due to earthquakes has a huge history of devastating and catastrophic damages to civil engineering structures including permanent settlement, loss in bearing capacity, slope failure, etc. The severity of soil liquefaction is observed in both loose as well as dense sandy soils (Castro 1975). Therefore, the evaluation of undrained shear and dynamic parameters, as well as the study of static and cyclic shear behaviour at different stress-history of soil, is of utmost importance for general design practices. The current study was carried out on the Fatehgarh earthen dam soil located in the Kutch region of Gujarat, India. This region lies in high-risk seismic zone-V and has experienced major destructive earthquakes over the last two decades. The Kutch region mainly consists of silty-sand soil with slight traces of clay (Rajendran and Rajendran 2001).