Impact wave propagation in tall buildings using advanced spectral element method

One of the major divisions in analysis and design of tall buildings is to account for forces induced by flying‐object impact and the subsequent progressive collapse. During the past three decades, problems of contact mechanics have been considered by some authors, and special attention has been devoted to high‐speed impact. Impact wave propagation in tall buildings may be analysed using the conventional finite element method. However, in order to guarantee stability and accuracy of the solution, the number of elements used to model the structure may be very large indeed; more precisely, accurate results can be obtained after a substantial computational effort. In this respect, an improved complex spectral element method is developed for analysing the wave propagation problems in large structures. The purpose of this paper is to obtain the resulting dynamic responses of a tall building induced by a high‐speed impact of a flying object. Copyright © 2003 John Wiley & Sons, Ltd.     

Seismic methods for study of soil building properties

Bulletin of Engineering Geology and the Environment - Information about distribution of elastic wave propagation velocities Vp, Vs in the subsurface zone of a soil mass can be obtained rapidly and...     

Thermorheological model of a frozen-soil continuum

A method of evaluating the stress-strain state of frozen soils, which takes into account the existence of elastoviscoplastic and temperature deformations over time under variable external effects, is described. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 10–13, July–August, 1997.     

Long-term geophysical observations on the inguri dam rock foundation

Bulletin of Engineering Geology and the Environment - It has been found that during construction of the dam, prior to the filling of the reservoir, compaction and loading of the rocks under the...     

Combined nitrification/denitrification in a membrane reactor

An ever stricter legislation regulating wastewater leads to an increasing demand for biological treatment plants which are able to selectively eliminate nitrogen from wastewaters with a high influent concentration, even when operating in partial influent mode. A membrane-tube-module (MSM) reactor (Membran-Schlauch-Modul-Reaktor) was constructed and realized in the IUV at the University of Bremen. The present approach makes use of all the various layers of the whole biofilm, enabling nitrification and denitrification processes to run simultaneously in one and the same biofilm under optimized conditions. The biological degradation capacity of the system was first successfully tested with synthetic wastewater, and subsequently in a real application with effluents from a recycling of animal carcasses plant and from a coke-oven plant. A mathematical model was devised which describes this biofilm system. The resulting equations were solved by means of the simulation software AQUASIM.     

Experience with algal blooms and the removal of phosphorus from sewage

The growth of algae and occurrence of algal “blooms” in a number of different waters are described.They cover the period 1930–1940 when only natural phosphates would be present.The waters were drawn from either protected catchments or from a fully treated domestic supply.Spasmotic blooms in a fully treated domestic supply suggest that the mechanism which “triggers” the start of an algal bloom may be neither nutrient concentration nor the concentration of organic matter.It is considered that the pH, alkalinity, carbon dioxide equilibrium condition is a major factor, not only in promoting, but also in maintaining algal blooms.     

The bacterial population of piggery-waste anaerobic digesters

A survey was made of the anaerobic and facultatively anaerobic bacteria present in piggery waste, digesting piggery waste and domestic anaerobic sludge sludge used to start a piggery waste digester. An influence of the input waste was shown in that streptococci, the predominant facultatively anaerobic bacteria in the piggery waste, were the predominant bacteria in the digesting waste, and they replaced Enterobacter, predominant in the domestic sludge, when a piggery waste digestion had been established from this latter material. Cellulolytic or methanogenic bacteria could not be detected in the piggery waste but populations of these, and other hydrolytic bacteria, became established at different times during the buildup of digestion by gradual addition of piggery waste to water. The bacteria concerned in degradation of the waste constituents were all anaerobes.Production of methane from H₂/CO₂, formate and butyrate could be detected in mixed cultures from dilutions of digester contents, but the only methanogenic bacterium that could be isolated in pure culture was Methanobacterium formicicum, which uses H₂/CO₂ or formate only.     

Earthquake analysis of isotropic asymmetric multistory buildings

Isotropic multistory buildings are the ones characterized by the property: all load‐resisting planar frames have proportional lateral stiffness matrices. In the present paper it is proved that the modal analysis of an N‐story isotropic asymmetric, torsionally coupled, building (a problem of order 3N) can be separated into two independent sub‐problems: (a) a sub‐problem that corresponds to a single‐story asymmetric, torsionally coupled, building (a problem of order 3); and (b) a sub‐problem that corresponds to an N‐story, torsionally uncoupled, planar frame (a problem of order N). It is also demonstrated that the orientation of peak modal seismic forces of the building is independent of the orientation of seismic excitation, which affects only their size. The separation provides a better insight into the structural behavior of asymmetric multistory buildings under earthquake ground motion. Copyright © 2006 John Wiley & Sons, Ltd.     

Experimental studies on the weatherability of the capivara dam basalts,rio paranapanema,brazil

The weatherability of the basalts in the Capivara Dam site, Rio Paranapanema, São Paulo State, Brazil, has been studied by means of saturation-drying tests. A great number of samples have disaggre — gated intensively with production of fines. The behavior of these rocks is related to their petrography, especially to their content in expansive clay minerals. These studies were performed in order to obtain data for the utilization of this material as rock fill, including ripraps.