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Showing 3 results for Environmental Conditions

M.h. Sebt, H. Rajaei, M.m. Pakseresht,
Volume 5, Issue 3 (9-2007)
Abstract

Project participants are becoming more aware of the high costs and risks associated with delay claims and their litigation. Among delays, weather delay has an important role in projects performed in severe environmental conditions. This research is the extension of delay analysis techniques by approving analysis of weather delays using fuzzy logic. At the presented technique, first using a fuzzy logic model calculated the delay that occurred during the activity execution after weather event then by the selected delay analysis method (Time impact analysis) and using the risk of the contractor during the contract approval together with the effect of previous delay in changing the duration of activities, analyzed weather delays in construction project. A local general contractor and governmental firms involved in a highway construction project practiced by offering their experienced and knowledge in delay analysis procedures to provide data for development and testing of the model specified for rain events. The results indicated that the presented model is in accordance with practical experiences in weather delay duration except in some circumstances that can be divided into the separated parts. It also advances the use of fuzzy logic in delay analysis procedures and becomes it more systematic special for weather delays.
P. Ghoddousi, A.m. Raiss Ghasemi, T. Parhizkar,
Volume 5, Issue 4 (12-2007)
Abstract

Plastic shrinkage is one of the most important parameter which must be considered in hot weather concreting. If plastic shrinkage is not prevented, cracking will be significant, especialy if silica fume is used in the mix. In this paper, the effect of silica fume in bleeding and evaporation was investigated in laboratory. The results showed that in restrained shrinkage, beside relative humidity, temperature and wind velocity, sun rediation also is very important factor in evaporation rate. It is found that under solar radition condition, the evaporation was much larger than the estimated value in ACI 305 Nomogram. The rate of evaporaion under solar radiation was about two folds of evaporation rate under shade condition. The results showed that in terms of crack initiation time, crack width and total cracking area, concrete containing silica fume is more severe than concrete with no silica fume. Reduction of water cement ratio in concrete with silica fume makes the concrete more sensitive in cracking. The results of this project also showed that the severity of the cracking is not related only to rate of bleeding but all environmental factors including like sun radiation or shading and also mix compositions have important roles.
Dr. Prasanta Bhuyan, Mr. Amit Das,
Volume 15, Issue 7 (10-2017)
Abstract

The present study aims at the divination of the speed ranges of Level of Service (LOS) categories of urban traffic facilities. Free flow speed (FFS), congested travel speed, geometric and surrounding environmental conditions are considered to define LOS criteria for urban street in Indian context. Cluster analysis is found to be a powerful tool to delineate LOS criteria. Hard Competitive Learning (hardcl) method is used to classify large number of speed data obtained using Global Positioning System (GPS). Six cluster validation parameters are used to classify the urban streets as well as the LOS categories. It can be confirmed from the above research work that the LOS categories for different urban street class are lower than that of the values proposed by HCM 2000 and the average travel speed of LOS categories expressed in percentage of the free flow speed are lower than the values mentioned in HCM 2010.



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