Seismic Analysis of Saturated Sand Deposits with Silt Layers

Liquefaction of saturated sands during earthquakes is known to be the cause of significant earthquake related damages, including loss of bearing capacity, lateral flow and spreading, slope failures. In recent earthquakes including the1999 Marmara Earthquake in Turkey, field observations have indicated that silt inclusions or silt layers in the sandy deposits can have significant effects on development of liquefaction. The objective of this work is to analytically study the behavior of saturated sand deposits with silt layers. For this purpose, a hypothetical soil profile in which silt layers exist has been selected. The selected profile was then modeled and analyzed using the LASS-IV code that has nonlinear effective stress analysis capability. As base motion, rock site recordings of the mentioned earthquakes were utilized. Furthermore, as part of this study, a parametric study has been conducted to further understand the effects of silt layers within sand deposits on the onset of liquefaction. The results of the analyses of various parameters such as depth of silt layer, the relative density of sand layer and maximum base acceleration were tabulated to summarize the effect of silt layers on the onset of liquefaction

An artificial neural networks model for the estimation of formwork labour / Dirbtinių neuroninių tinklų modelis, kurio paskirtis – skaičiuoti klojiniams skirto darbo apimtis

Artificial Neural Networks (ANN) is a problem solving technique imitating the basic working principles of the human brain. The formwork labour cost constitutes an important part within the costs of the reinforced concrete frame buildings. This study suggests a method based on artificial neural networks developed for estimating the required manhours for the formwork activity of such buildings. The introduced method has been verified in the study with reference to the test conducted involving two case studies. In all cases, the model produced results reasonably close to actual field measurements. The model is a simple and quick tool for the estimators and planners to aid them in their work. Santrauka Dirbtiniai neuroniniai tinklai (DNT) – tai problemų sprendimo metodas, imituojantis pagrindinius žmogaus smegenų veiklos principus. Statant gelžbetoninius karkasinius pastatus, nemažą sąnaudų dalį sudaro klojinių ruošimas. Šiame tyrime siūlomas dirbtiniais neuroniniais tinklais pagrįstas metodas, kurio paskirtis – apskaičiuoti, kiek žmogaus darbo valandų reikės ruošti klojinius tokiuose pastatuose. Pristatomas metodas tyrimo metu patikrintas remiantis bandymu, susijusiu su dviem atvejo tyrimais. Visais atvejais modelio pateikti rezultatai buvo gana artimi faktiniams matavimams. Modelis – tai paprastas ir greitai naudojamas įrankis, kuris pravers sąmatininkams ir planuotojams. Reikšminiai žodžiai: dirbtiniai neuroniniai tinklai (DNT), klojinys, darbas, sąnaudos, žmogaus darbo valanda, našuma