The Mexico Earthquake of September 19, 1985—Response and Design Spectra Obtained from Earthquake-Damaged Buildings

1989 ◽  
Vol 5 (1) ◽  
pp. 113-120 ◽  
Author(s):  
A. Gómez ◽  
R. Ortega ◽  
J. J. Guerrero ◽  
E. González ◽  
J. P. Paniagua ◽  
...  
Keyword(s):  
Mexico City ◽  
Shear Force ◽  
Response Spectrum ◽  
Base Shear ◽  
Natural Period ◽  
Safety Level ◽  
Design Spectrum ◽  
Design Spectra ◽  
Mexico Earthquake ◽  
High Seismicity

The resistant shear force of 13 buildings severely damaged by the 1985 Mexico City earthquake was determined by static and dynamic analyses. The results of the static analysis suggest the advisability of increasing the shear base coefficient of the 1987 Mexico City building code RDF87 from 0.4 to 0.6 in the high seismicity zones of the area. The results of the dynamic analysis show that in order to obtain the same safety level, the maximum ordinate of the design spectrum should be larger than the base shear coefficient used with the static method, leading to a 0.8 maximum ordinate for Mexico City. When the resistant shear force is plotted as a function of the natural period of each building, the response spectrum obtained is very similar to the inelastic spectrum derived from the accelerograms, considering 5% critical damping, a ductility factor of 4 and degradation in resistance from 5% to 10%. Based on these results, new design spectra are proposed for use in the high seismicity zones in Mexico City.

The Uncertainty in Shape Parameter Predictions of Seismic Design Spectra for Nuclear Power Plant

2013 ◽  
Vol 405-408 ◽  
pp. 2025-2029
Author(s):  
Long Jun Xu ◽  
Hong Zhi Zhang
Keyword(s):  
Nuclear Power ◽  
Response Spectrum ◽  
Response Spectra ◽  
Design Spectrum ◽  
Design Spectra ◽  
Motion Data ◽  
Construction Methods ◽  
Normalized Response Spectrum ◽  
Scaling Parameters ◽  
Large Earthquakes

Aiming at the uncertainty of design spectrum raised by the construction methods, a comparative study is conducted in which different methodologies performed calculations of seismic response spectra using the same set of ground motion data from recent large earthquakes. The results of the research allowed some estimates to be made of the scaling method and model uncertainty involved in these calculations. These results were compared with the uncertainty derived from the proposed spectrum of a double-parameter-based bi-normalized response spectrum (DPBNS) approach. It is concluded that the sources of uncertainty that the results reflected are mainly impacted by the spectral type, scaling parameters, as well as imposed fixed conditions adopted in the calculations, for the scaling of the design spectra. Then, a discussion is provided on the limitations of these predications, in particular, of the approaches adopted in the construction of seismic spectra.

Rational Design Spectra for Structural Reliability Assessment Using the Response Spectrum Method

2015 ◽  
Vol 31 (4) ◽  
pp. 2007-2026 ◽  
Author(s):  
Christophe Loth ◽  
Jack W. Baker
Keyword(s):  
Rational Design ◽  
Structural Reliability ◽  
Response Spectrum ◽  
Reliability Assessment ◽  
Structural Response ◽  
Response Spectrum Method ◽  
Design Point ◽  
Design Spectrum ◽  
Design Spectra ◽  
Spectrum Method

Current design spectra, which approximate uniform hazard or risk spectra, are known to have shortcomings, but no alternative has been proven superior for the purposes of design checks. In this work, we use response spectrum method analysis to show that the “design point” associated with a structural reliability assessment is a rational choice for a design spectrum. When the response parameter of interest is sensitive to excitation at a particular period, the design point corresponds to a conditional mean spectrum (CMS) conditioned on that period. In the case where there are multiple structural response parameters of interest, or it is unknown what excitation periods are important to the structural response, the CMS can be used by considering multiple conditioning periods and taking the maximum structural response from any of the spectra for design checks. This observation is used to justify the CMS as a target response spectrum for design checks.

scholarly journals Dynamic Analysis of Steel Silo

2020 ◽  
Vol 9 (1) ◽  
pp. 1986-1990
Keyword(s):  
Dynamic Analysis ◽  
Linear Time ◽  
Response Spectrum ◽  
Structural Response ◽  
Time History ◽  
Time History Analysis ◽  
Base Shear ◽  
Natural Period ◽  
History Analysis ◽  
Lateral Displacements

The structural response of any structure is the result of various dynamic phenomenon which lead to vibrations or shaking of the structure , depending on the duration of the ground motion, its frequency and time period. In the present work, dynamic analysis of a typical steel silo is done by using linear Time History Analysis and Response Spectrum method for earthquake Zone V as per Indian code. Two analyses are carried out namely, Time History Analysis (THA) and Response Spectrum Analysis (RSA) using STAAD.ProV8i software. The Load combinations are worked out as per IS-1893-2002. The results in terms of Fundamental natural period, Design Base shear, Lateral Displacements, are compared for the two different silo models considered in the present study.

EFFECTS OF RANDOMLY DISTRIBUTED INFILL ON COLUMNS OF REINFORCED CONCRETE FRAMES WITH SOFT GROUND STOREY

2010 ◽  
Vol 10 (03) ◽  
pp. 555-569 ◽  
Author(s):  
SHAHRIAR QUAYYUM ◽  
ISLAM MOHAMMAD NAZMUL ◽  
MOST. MAHBUBA IASMIN ◽  
KHAN MAHMUD AMANAT
Keyword(s):  
Reinforced Concrete ◽  
Response Spectrum ◽  
Base Shear ◽  
Concrete Frames ◽  
Natural Period ◽  
Rc Frames ◽  
Axial Forces ◽  
Open Ground ◽  
Seismic Loadings ◽  
Structural Responses

Reinforced concrete (RC) frames with an open ground floor and various infill distributions have been analyzed for seismic loadings by the finite element method. The infills have been modeled by diagonal struts. Focus is placed on the effects of infill distribution on various structural responses, including (i) the lateral deflection, (ii) the column axial forces, (iii) the column bending moments, (iv) the base shear, and (v) the natural period of the frame. The equivalent static force method (ESFM) and response spectrum method (RSM) for linear structures have been applied, and the results obtained have been compared. It was found that the structural responses do not change appreciably by the ESFM analysis for random infill distributions, while they increase noticeably in the RSM analysis. This manifests the inadequacy of using the ESFM for general purposes, for which modifications were proposed in this paper for the design of RC columns. As the natural period of the RC frame converges with the code equations only for higher amounts of infill, it is necessary to incorporate the amount and distribution of infill in the dynamic analysis of RC frames.

The Mexico Earthquake of September 19, 1985—Behavior of Building Foundations in Mexico City

1988 ◽  
Vol 4 (4) ◽  
pp. 835-853 ◽  
Author(s):  
M. J. Mendoza ◽  
G. Auvinet
Keyword(s):  
Mexico City ◽  
Soft Soil ◽  
Shear Forces ◽  
Natural Period ◽  
Plastic Deformations ◽  
Long Period ◽  
Cyclic Stresses ◽  
Static Contact ◽  
Mexico Earthquake ◽  
Main Factor

During the 1985 earthquake, a number of building foundations in the lacustrine soft soil area of Mexico City presented an inadequate performance. Previous high static contact stresses between the foundation and the supporting subsoil propitiated the appearance of plastic deformations of the soil under seismic cyclic stresses, which led to settlements and tilting of the buildings. Foundations of all kinds showed different degrees of vulnerability to the earthquake, but constructions on friction piles sustained the most severe damages. This can be attributed in some cases to non compliance with the accepted design criteria and current regulations. The main factor was however the pronounced dynamic magnification of seismic movements associated to the quasi coincidence between the natural period of some structures with moderate height on friction piles, and the long period of the subsoil motions, which led to large overturning moments and shear forces at the foundation level.

Comparison of Base Shear Force Method in the Seismic Design Codes of China, America and Europe

2012 ◽  
Vol 166-169 ◽  
pp. 2345-2352
Author(s):  
Zhi Nan Jiang ◽  
Zhong Hai Zhao
Keyword(s):  
Seismic Design ◽  
Shear Force ◽  
Response Spectrum ◽  
Base Shear ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Force Method ◽  
Frame Building ◽  
Design Response Spectrum ◽  
Seismic Forces

Seismic design response spectrum and earthquake action in Chinese new seismic code (GB50011-2010), ASCE/SEI7-05 and Eurcode8 were gathered in this paper. Using base shear force method of each code, the authors computed the horizontal seismic forces of a three-story reinforced concrete frame building under the same conditions. The results show that the three static methods roughly approach, while the different parameters lead to discrepancies in calculated values.

scholarly journals A structural performance evaluation of vertical housing model due to the increased seismic loads in Semarang, Indonesia using a pushover analysis

2018 ◽  
Vol 195 ◽  
pp. 02018 ◽  
Author(s):  
Arnie Widyaningrum ◽  
Yanuar Haryanto ◽  
Nor Intang Setyo Hermanto
Keyword(s):  
Shear Force ◽  
Response Spectrum ◽  
Pushover Analysis ◽  
Structural Performance ◽  
Seismic Loads ◽  
Base Shear ◽  
Site Class ◽  
Design Response Spectrum ◽  
Immediate Occupancy ◽  
Regulation Changes

The substantial increase in design response spectrum is resulted from the Indonesian seismic regulation changes, which occur in Semarang as well, either for hard, medium or soft site class. The increased design response spectrum is linear to the increased seismic loads, which may influence the structural performance of buildings in Semarang. We have conducted a study on the influence of increased seismic loads on the performance of an irregular ten-story vertical housing model of medium site class in Semarang, Indonesia. The study is conducted using a pushover analysis. We find that the increased seismic loads in Semarang has resulted in the increased base shear force and structural drift of the analysed vertical housing model. The base shear force increases by 68.96% in X direction and 66.63% in Y direction, while the structural drift ratio increases by 81.25% in X direction and 82.64% in Y direction. However, the structural performance remains at Immediate Occupancy, which refers to a condition of post-earthquake damage where the building is still regarded as safe to live in.

The Mexico Earthquake of September 19, 1985—Seismic Zoning of Mexico City after the 1985 Earthquake

1989 ◽  
Vol 5 (1) ◽  
pp. 257-271 ◽  
Author(s):  
J. Iglesias
Keyword(s):  
Mexico City ◽  
Soft Soil ◽  
Resistance Coefficient ◽  
Seismic Zoning ◽  
Base Shear ◽  
Severe Damage ◽  
Seismic Capacity ◽  
Mexico Earthquake ◽  
The City ◽  
Resistance Coefficients

Using a simplified method for the evaluation of the seismic capacity of medium rise concrete structures, it was possible to obtain the base shear coefficient corresponding to failure (resistance coefficient) for 162 buildings, and use it as an evaluation index. The resistance coefficients of the 90 evaluated structures that suffered severe damage were used to elaborate a map of intensities for the 1985 Mexico City earthquake. This map shows the strong interaction of neighboring zones of firm soil or rock that amplify the ground motion in the soft soil between them as much as 100%, this being the main reason for the high intensities observed in some districts of the city. Based on these results, a new seismic zoning was proposed for the chapter of the 1987 Mexico City Building Code.

scholarly journals Effect of Bottom Geometry on the Natural Sloshing Motion of Water Inside Tanks: An Experimental Analysis

2021 ◽  
Vol 11 (2) ◽  
pp. 605
Author(s):  
Antonio Agresta ◽  
Nicola Cavalagli ◽  
Chiara Biscarini ◽  
Filippo Ubertini
Keyword(s):  
Energy Dissipation ◽  
Water Depth ◽  
Shear Force ◽  
Experimental Tests ◽  
Shear Load ◽  
Damping Properties ◽  
Base Shear ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
Key Aspects

The present work aims at understanding and modelling some key aspects of the sloshing phenomenon, related to the motion of water inside a container and its effects on the substructure. In particular, the attention is focused on the effects of bottom shapes (flat, sloped and circular) and water depth ratio on the natural sloshing frequencies and damping properties of the inner fluid. To this aim, a series of experimental tests has been carried out on tanks characterised by different bottom shapes installed over a sliding table equipped with a shear load cell for the measurement of the dynamic base shear force. The results are useful for optimising the geometric characteristics of the tank and the fluid mass in order to obtain enhanced energy dissipation performances by exploiting fluid–structure interaction effects.

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