Seismic Microzoning and Resonant Map for Urban Planning


Abstract eng:
The today's cities are dealing with permanent demands to extend their residential and economical facilities. The existing urban zones are being revised with new regulating urban plans to increase their accommodation capacity by replacing, annexing or upgrading existing building structures. In other cases the urban zones are being expanded to neighboring areas, sometimes irrespective of vulnerable environment. This study aims to identify the potential for resonance effect between soil sub-base and building stock in urban zones, being that existing settlement or new settlements foreseen in the stage of urban planning. Prior to the development of the resonant map, several multidisciplinary site activities are necessary to be performed in order to have a working platform for decision making authorities. Procedure shall be initiated with seismic microzoning of the respective area, obtained with use of geotechnical examinations, geophysical investigations, and microtremor measurements. The obtained results shall then be used to develop the maps with predominant surface periods of vibrations, dynamic amplification factors and seismic zoning with design parameters. Following, predominant periods of vibrations for built structures are obtained with application of ambient vibration measurements (existing structures) or modal analysis (planned structures). Seismic microzoning is the key to obtain the site specific data upon soil strata performance due to expected earthquake excitations. It gives information’s upon the amplification/attenuation of seismic excitations from the bedrock to the ground surface. Modification of the seismic excitation is governed from the site specific ground conditions, presented on ground surface as mean values of the ratio of maximum accelerations at the surface versus acceleration of subsoil media – expressed through dynamic amplification factors (DAF). The excerpted values shall help to create initially the maps with isolines of DAF and then seismic microzoning map with expected maximum mean surface acceleration as a product of DAF with maximum accelerations at the respective bedrock. Development of resonant map shall conglomerate the information’s obtained from seismic microzoning in regard to expected predominant ground periods of seismic excitation and periods of vibrations of built/designed structures. Elastic dynamic properties of built structures can be obtained with application of ambient vibration measurements, with use of digital seismometers equipped by 3 orthogonal high resolution electrodynamics sensors (velocimeters) with frequency range 0.1 – 256 Hz. All these information’s can be concluded with draft of Resonant Map, which can be used as indispensible tool in early stages of urban planning to determine the most optimal zones for construction, structural systems and materials, range of buildings height, etc. Analysis could help to define the urban criteria’s for zoning and construction, so the resonance of soil media with built structures is avoided. Resonant Map can be used to identify the existing building stock with expected critical seismic response and also for assessment of seismic risk and vulnerability-damageability of existing urban environments.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 4086.:
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