Direct damage controlled seismic design of plane steel degrading frames

A new method for seismic design of plane steel moment resisting framed structures is developed. This method is able to control damage at all levels of performance in a direct manner. More specifically, the method: (a) can determine damage in any member or the whole of a designed structure under any given seismic load, (b) can dimension a structure for a given seismic load and desired level of damage and (c) can determine the maximum seismic load a designed structure can sustain in order to exhibit a desired level of damage. In order to accomplish these things, an appropriate seismic damage index is used that takes into account the interaction between axial force and bending moment at a section, strength and stiffness degradation as well as low cycle fatigue. Then, damage scales are constructed on the basis of extensive parametric studies involving a large number of frames exhibiting cyclic strength and stiffness degradation and a large number of seismic motions and using the above damage index for damage determination. Some numerical examples are presented to illustrate the proposed method and demonstrate its advantages against other methods of seismic design. © 2014, Springer Science+Business Media Dordrecht

USEE 2001: Utility Software for Earthquake Engineering Report and User's Manual

National Science Foundation EEC-970178

EFFETS DE L'ADMINISTRATION CHRONIQUE DE STÉROÏDES ANTICONCEPTIONNELS SUR L'ÂGE BIOLOGIQUE DES CYCLES OVARIENS DE LA RATTE APRES ARRÊT DU TRAITEMENT

International audienc

The Bhuj Earthquake of 2001

The decision to send a team of earthquake engineering researchers and seismologists half way around the world to investigate a tragic earthquake was indeed a difficult one to make considering the circumstances. Logistical problems, from obtaining visas to transporting large equipment packages to mobilization in the field, were enough by themselves to find every reason for not having a reconnaissance effort. Moreover, risks posed by health and safety of investigators in the disaster region, along with the myriad of political issues and high costs associated with an international study of this degree, required much contemplation before a decision was made to deploy a team of investigators. However, an affirmative decision was made because of the benefits that the investigation would have with regard to the Center???s emphasis on earthquake loss reduction in the Central United States. Whereas no two earthquakes and their resulting consequences are identical, similarities between the New Madrid and Bhuj earthquakes, as noted is this report, were sufficient to justify sending a team.National Science Foundation EEC-970178

Dependency of COD on ground motion intensity and stiffness distribution

Large changes in stiffness associated with cracking and yielding of reinforced concrete sections may be expected to occur during the dynamic response of reinforced concrete frames to earthquake ground shaking. These changes in stiffness in stories that experience cracking might be expected to cause relatively large peak interstory drift ratios. If so, accounting for such changes would add complexity to seismic design procedures. This study evaluates changes in an index parameter to establish whether this effect is significant. The index, known as the coefficient of distortion (COD), is defined as the ratio of peak interstory drift ratio and peak roof drift ratio. The sensitivity of the COD is evaluated statistically for five- and nine-story reinforced concrete frames having either uniform story heights or a tall first story. A suite of ten ground motion records was used; this suite was scaled to five intensity levels to cause varied degrees of damage to the concrete frame elements. Ground motion intensity was found to cause relatively small changes in mean CODs; the changes were most pronounced for changes in suite scale factor from 0.5 to 1 and from 1 to 4. While these changes were statistically significant in several cases, the magnitude of the change was sufficiently small that values of COD may be suggested for use in preliminary design that are independent of shaking intensity. Consequently, design limits on interstory drift ratio may be implemented by limiting the peak roof drift in preliminary design

A random coefficient model of speculative attacks: The case of the Mexican peso

A considerable body of theoretical and empirical literature has developed seeking to explain the timing, magnitude, and mechanics of speculative attacks against currencies. This paper extends the empirical specification of the traditional speculative attack model by developing a random coefficient (RC) model which, as we show, encompasses a variety of fixed-coefficient models as special cases. Two classes of models (fixed- and random-coefficient models) are estimated for the case of Mexican peso over the period January 1988 to Novemeber 1994, while forecasts of the peso/U.S. dollar exchange rate are generated for the period December 1994 through December 1995. The comparison of forecast errors generated by five model specifications indicates that forecasts based on the RC procedures are superior to those based on the fixed-coefficient estimation. It is also shown that there are good theoretical reasons why the RC procedure performs better in prediction than the fixed-coefficient procedure. Copyright Kluwer Academic Publishers 1996Random Coefficient Models, Forecasting, Speculative Attacks, C22, C51, F31, F33,