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Non-prescriptive approaches to enhanced life cycle seismic performance of buildings
Published in Dan M. Frangopol, Hitoshi Furuta, Mitsuyoshi Akiyama, Dan M. Frangopol, Life-Cycle of Structural Systems, 2018
Typical strength performance requirements are defined in the high-rise building code (ISPRC-10), and are designated for Performance Levels A to D instead of corresponding Levels 1 to 4 as in the case of the seismic code (NSPRC-10). Table 3 provides an example of the enhanced strength performance requirements for a tall frame-core wall reinforced concrete structure.
Some challenges to earthquake engineering in a new century
Published in B.F. Spencer, Y.X. Hu, Earthquake Engineering Frontiers in the New Millennium, 2017
It is noteworthy that all major earthquake disasters during the past twenty years have occurred in countries where the seismic design code were available, so it is clear that having a seismic code no sufficient to prevent earthquake disasters. Examples of such disastrous earthquakes are the 1999 Izmid, Turkey Earthquake; the 1999 Jiji, Taiwan China Earthquake; the 1995 Henshin, Japan Earthquake; the 1994 Northridge, California U.S. Earthquake; the 1976 Tangshan, China Earthquake; and many others. In the past, the usual procedure for upgrading seismic code has been to wait until a destructive earthquake occurred and then to change the building code to strengthen the demonstrated weakness, and then wait for the next earthquake to demonstrate other weakness. This is not an efficient way of reducing earthquake disasters. It would be more advantageous to improve the seismic code as new knowledge is developed by research and experience, rather than to build under the existing code while waiting for the next earthquake. In drafting a new seismic code, or revising an existing code, it is necessary to balance the cost of seismic design against the reduction of future losses from earthquakes. The estimation of future losses must recognize not only structural damage but also the economic and social impacts that can be very severe. (Housner 1996).
Performance-based seismic engineering: A critical review of proposed guidelines
Published in Peter Fajfar, Helmut Krawinkler, Seismic Design Methodologies for the Next Generation of Codes, 2019
After a detailed review of the U.S. Building Code philosophy and the history of the seismic code provisions, Bertero [1992] made the following observations: Although in recent years the understandingof EQ engineering problems and EQ-RD has undergone remarkable development, and building codes to which ordinary buildings are designed have also developed impressively, particularly in regard to sizing and detailing of their superstructures, buildings designed in conformance with present seismic code regulations cannot guarantee the accomplishment of the above main goals, and particularly the objectives of the EQ-RD philosophy. Uang and Bertero [1991] have shown that the UBC specified seismic design procedure cannot adequately control the general demands that can be imposed by service EQGMs.In the last two decades there have been tremendous improvements in the code specifications for the sizing and detailing of structural members and their connections and supports, particularly in the case of RC structures, through stringent requirements to achieve high ductility. These stringent requirements for sizing, and particularly for detailing, have been the blessing of the current seismic code requirements. The author believes that these stringent requirements, rather than complex numerical analyses conducted to comply with code formulae for estimating demands, have permitted many buildings to survive recent moderate to severe EQGMs.Modern building codes, which try to reflect great advances in knowledge and understanding in a very simple way, are not transparent about the expected level of performance of the whole building system (soil-foundation-superstructure and nonstructural components). Expected level of performance has become an implicit rather than explicit part of the codes through a series of empirical factors and detailing requirements which obscure the true nature of the EQ-RD problem: building performance.There can be no improvement in the EQ-RD of new buildings, in seismic performance evaluation of existing buildings, or in vulnerabililty assessment and upgrading of hazardous buildings, if there is no improvement in predicting stiffness, strength, and energy absorption and dissipation capacities of real building systems (soil-foundation-superstructure and nonstructural components).
Seismic Hazard Analysis of Vadodara Region, Gujarat, India: Probabilistic & Deterministic Approach
Published in Journal of Earthquake Engineering, 2022
Seismic hazard analysis of any region is one of the approaches to mitigate against the earthquake hazards. Indian peninsula is considered as one of the stable continental region of the world. But the few large earthquakes during last past decades have changed the scenario of peninsular India (PI). Indian seismic zoning map (IS 1893, 2016) development started way back in 1935, and it has been revised time to time with the addition of new knowledge and appropriate parameters. The last revision of National seismic code arrives in 2016 (IS 1893, 2016). In the present code, the whole country is divided in four seismic zones with the response spectra considering various soil/rock type (IS 1893, 2016). As per IS:1893–2016, peak ground acceleration (PGA) value is same irrespective of any type of soil. (Rethaliya, Patel, and Rethaliya 2018). However, this code is also not able to pick variations due to local site conditions. In such situations, role of local site effects at regional level becomes very crucial. Deterministic seismic hazard analysis (DSHA) and probabilistic seismic hazard analysis (PSHA) are the two approaches to develop the seismic hazard model of any region. DSHA approach considers the past seismicity and seismotectonic setup of any region to determine maximum possible ground motion at a site. PSHA approach aims to quantify the probability of a specified level of ground motion being exceeded at a particular site considering the uncertainties associated with earthquakes in terms of location, size and intensity of future earthquake.