Scaling of ductility and damage‐based strength reduction factors for horizontal motions

The conventional approach of obtaining the inelastic response spectra for the aseismic design of structures involves the reduction of elastic spectra via response modification factors. A response modification factor is usually taken as a product of (i) strength factor, R_S, (ii) ductility factor, R_μ, and (iii) redundancy factor, R_R. Ductility factor, also known as strength reduction factor (SRF), is considered to primarily depend on the initial time period of the single‐degree‐of‐freedom (SDOF) oscillator and the displacement ductility demand ratio for the ground motion. This study proposes a preliminary scaling model for estimating the SRFs of horizontal ground motions in terms of earthquake magnitude, strong motion duration and predominant period of the ground motion, geological site conditions, and ductility demand ratio, with a given level of confidence. The earlier models have not considered the simultaneous dependence of the SRFs on various governing parameters. Since the ductility demand ratio is not a complete measure of the cumulative damage in the structure during the earthquake‐induced vibrations, the existing definition of the SRF is sought to be modified with the introduction of damage‐based SRF (in place of ductility‐based SRF). A parallel scaling model has been proposed for estimating the damage‐based SRFs. This model considers damage and ductility supply ratio as parameters instead of ductility demand ratio. Through a parametric study on ductility‐based SRFs, it has been shown that the hitherto assumed insensitivity of earthquake magnitude and strong motion duration may not be always justified and that the initial time period of the oscillator plays an important role in the dependence of SRF on these parameters. Further, the damage‐based SRFs are found to show similar parametric dependence as observed in the case of the ductility‐based SRFs. Copyright © 2000 John Wiley & Sons, Ltd.     

Model tank experiments for resistivity measurements on sloping and vertical non conducting dykes

Summary Model resistivity experiments over sloping and vertical, non-conducting dykes have been carried out and reported in this paper. The results of vertical dykes as compared to the sloping dykes are very interesting and not so far reported in the available literature. Of particular interest is distinct resistivity high in the centre of the two vertical dykes, followed by lows over the dykes and again by highs on either side. As expected the curves are symmetrical. As against this, in the cases of sloping dykes, there is a distinct low, in between the dykes, followed by highs over the dykes, the curves being asymmetrical.     

Simple Electrical Logging Technique for Base Metal Exploration

—It is well known that electrical logs of boreholes can play a signi|fi|cant role in base metal exploration in identifying mineralised zones, especially when there is core loss or the borehole diameter is small or if drilling is by percussion. However, electrical logging is not widely utilised because of the additional burden on finances and time.¶A simple electrical logging technique, based on a pole-pole (hole-to-surface) configuration with one borehole electrode and nearly akin to the single point method, for S.P., resistivity and I.P. parameters, is presented. It is shown that it has the resolution of the single point method and the penetration of a very long normal sonde which is helpful for detection. Besides these features, the main advantage of this technique is that it can be easily carried out using ground I.P. (time domain) equipment.¶The electrical logs obtained in different base metal belts in Rajasthan, India, employing this technique and using ground I.P. equipment in connection with mise-à-la-masse surveys, illustrate the above features. A comparison with logs recorded by means of multi-electrode drill hole I.P. equipment of Scintrex, Canada, substantiates the same.     

On pressure waves in the coastal region

Summary Several authors have tried to explain the different aspects of pressure waves in water including the phenomenon of «Singing» by assuming another fluid layer below the water column. In this note an attempt has been made to determine the thickness of such a layer.     

Short Term Effects of Aldrin and Swascofix CD-38 on the Feeding and Respiratory Behaviours of Clarias batrachus and Cirrhina mrigala

Fish were kept in non-toxic water or at 0.5, 0.25 and 0.125 of the LC_50,96h of the ten-side or insecticide for 24 h and fed with toxified and non-toxified feed. Toxified feed in normal water resulted in a maximum feed intake, while normal feed in toxified water resulted in a minimum one. In each case, the feed intake was lower compared with the control, and the feed intake was inversely proportional to the toxicant concentration. In a simple respirometer the oxygen consumption in mg · kg^?1 · h^?1 was tested for 1, 2, 4, 6, 8, 10, 12, 24, 36, 48, 60, 72, 84 and 96 h of exposure to 1.5, 1.0 and 0.5 of the LC_50,96h of both substances. It was a flow device which was closed only for measurement for one hour. 1.5 LC₅₀ Aldrin causes a continuous reduction of respiration until death. The same effect occurred with Cl. batrachus for 1.5 LC₅₀ of the tenside, whereas with C. mrigala death was caused by a pronounced increase of respiration. In all other cases, after a phase of sensitization for 4 … 8 h respiration increased considerably to more than 300% of the control, which was followed after 12 … 24 h by acclimatization to normal respiration values.     

Environmentally sustainable use of sandstone slurry in self-compacting concrete

Natural Hazards - Dried sandstone slurry (DSS) is generated during mining and processing of stone and is accounted as man-made hazardous waste material, contaminating the environment in nearby...