A Suggestion to the Vertical Earthquake Action Stipulated in Seismic Design Specification

In order to further regulate the vertical earthquake action in seismic design specification, to overcome the unreasonable and inconvenient flaws in certain conditions by using vertical to horizontal spectra ratio function, the feasibility of stipulating vertical design response spectrum with the same way of horizontal one is deal with in this paper. 1513 sets of three component records during 64 earthquakes from NGA-west1 database are selected and grouped by magnitude, distance and site conditions. Average acceleration response spectrum of each group is generalized to get the corresponding mean maximum amplitude and effective peak acceleration EPA. Furthermore, some groups with EPA in an interval are merged into one. Once again, the parameters, such as maximum amplitude and characteristic periods of each final grouping are acquired by the same way. The former is divided by the corresponding horizontal value for site category, to obtain the site coefficient for vertical action. Finally a preliminary suggestion of vertical site coefficient and characteristic period are presented. Comparison of observed data with results from the new suggestion and those from spectral ratio shows that the improvement of this study is obvious.

Analysis of the Potential of Seismic Stability for the Southern Region of Tangshan Based on ArcGIS

To assess the potential of seismic stability for the southern region of Tangshan city, five factors are considered, including fault zones, engineering geological condition, hydrogeology condition, dynamic coefficient and site category. In this paper, the process and digitalization and visualization technology of evaluation method for site seismic stability is proposed based on ArcGIS. The overlay method is automatic realized and the seismic stability potential diagram of Tangshan and its southern region is given, which overcomes the drawback that can't automatic classification of other GIS instruments, then time is greatly saved and the efficiency is improved.

Influence Study of Different Site Type on Seismic Performance of Pipeline with Defects

With the further study on the exploration and development of oil fields,some oil fields have gone into the later period for developing gradually. The problems of oil pipeline are more and more prominent. Earthquakes have occurred frequently in recent years. So it is particularly important to study on the seismic performance of corrosive pipeline. Due to the length of pipeline, the geological condition is more complicated, the same pipeline across the site category may have a big distinction. The software of ANSYS was used in this paper to study pipelines with corrosion defects in different site types. The seismic response were calculated, thus various types of site conditions of the velocity, displacement and acceleration time-history response were obtained, and the results were compared and analyzed.

Free Field Surface Motion at Different Site Types due to Near-Fault Ground Motions

Seismic hazards during many disastrous earthquakes are observed to be aggravating at the sites with the soft soil deposits due to amplification of ground motion. The characteristics of strong ground motion, the site category, depth of the soil column, type of rock strata, and the dynamic soil properties at a particular site significantly influence the free field motion during an earthquake. In this paper, free field surface motion is evaluated via seismic site response analysis that involves the propagation of earthquake ground motions from the bedrock through the overlying soil layers to the ground surface. These analyses are carried out for multiple near-fault seismic ground motions at 142 locations in Mumbai city categorized into different site classes. The free field surface motion is quantified in terms of amplification ratio, spectral relative velocity, and spectral acceleration. Seismic site coefficients at different time periods are also evaluated for each site category due to near-fault ground motions from the acceleration response spectra of free field surface motion at each site and the corresponding acceleration response spectra at a reference rock outcrop site.

A new way of assessing clay cation adsorption using normalized salt concentration

Kaolinite cation adsorption data are processed using recent gas adsorption concepts such as the undersaturation ∆m = ln (C/Cs) and the monolayer coverage y. This process shows that using the proper reference phase through its solubility Cs, it is possible to characterize adsorption sites that have the same adsorption energy regardless of the nature of the cation. Under mildly acidic conditions, a single ‘Langmuirian’ site category fits cation adsorption data whereas another family of sites is revealed in mildly alkaline conditions. These results suggest that at mildly acidic pH, only silanol sites are available to ion exchange and adsorption whereas at higher pH, a wider range of sites is made available, some of them displaying the same average adsorption energy and the others constituting a different category of sites with a much lower adsorption energy. This latter category is attributed to the aluminol sites.