International Journal of Civil Engineering
Volume:11 Issue: 1, Mar 2013

The aim of this paper is to deal with the multi-mode resource-constrained project scheduling problem under bi-random phenomenon in a practical large-scale water conservancy and hydropower construction project. A multiple objective decision making model with bi-random coefficients in the constraint is first proposed for practical drilling grouting project scheduling problem to cope with hybrid uncertain environment where twofold randomness exists. Subsequently, the chance constraint operator is employed to handle bi-random variable. Furthermore, particle swarm optimization algorithm is applied to search for the optimal solution. The results generated by computer validate the effectiveness of the proposed model and algorithm in solving large-scale practical problems.

This research presents a dynamic mathematical system for modeling and simulating the quality management process in construction projects. Through sets of cause and effect feedback loops, all factors that internally and externally affect the quality management process are addressed. The proposed system integrates fuzzy logic with system dynamics simulation scheme to consider the uncertainties associated with the model parameters and estimation of the extra cost and time due to quality defects. Quantification of the consequences of the quality failures is performed based on the α-cut representation of fuzzy numbers and interval analysis. The proposed approach is efficient in modeling and analyzing a quality management process which is complex and dynamic in nature and involves various uncertainties. The proposed approach is implemented in a sample real submarine water supply pipe line project in order to evaluate its applicability and performance. The negative impacts resulting from quality failures are simulated. These negative impacts are mitigated by the implementation of alternative solutions.

Construction industry consists of several phases in which a variety of stakeholders are involved. As construction projects are becoming larger, more complex and more diverse, the design phase has been more important factor for the success of projects than ever before. However, it is considered that most of design work occurred in actual design process is intangible. Such recognition makes the design phase more unsystematic and arbitrary, which finally weakens the competitiveness of whole project. In order to solve these problems, this study developed a web-based system for integrated design management (IDMS) which consists of 8 modules including design document, schedule, quality, and building permit management. This section is intended to validate the system implementation and its effectiveness. Two characteristics have made this research significantly different from previous studies. First of all, users of the system including architects and other design professionals were continuously involved starting from the development phase to the validation phase. The other unique characteristic is that the actual design project was applied as a test bed in the final verification stage. The research team applied the actual data which had been generated while each business process, and verified the effectiveness of system implementation. The authors expect that such a user-centered approach enable the system more robust and effective.

Since the 1990's, network reliability has been considered as a new index for evaluating transportation networks under uncertainty. Researchers have done various works in order to develop relevant measures that can be accommodated to different sources of uncertainty, such as daily traffic flow fluctuations, natural disasters, weather conditions, and so fourth. This paper addresses the problem of resource allocation in which not only the budget but also the performance reliability should be met at the desired levels given by the decision maker. For this purpose, a new approach has been considered to formulate the two well-known performance measures, connectivity and capacity reliability, along with their application in a bi-objective nonlinear mixed integer goal programming model. In order to take the uncertain conditions into account the capacity of links are assumed to be random variables and follow normal distribution functions. The effective innovation applied here is that the performance indices are calculated simply by means of link's performance reliabilities. The performance reliability of each link can be computed through integration of probability densities from traffic volumes to maximum link capacities. Numerical results are also provided in a simple network to demonstrate the capability of the proposed method.

In this paper a new approach for bus network design has been present that takes into account the effects of three stages out of the four steps of the bus planning process. The presented model includes three majors steps; 1- Network Design Procedure (NDP). 2- Frequency Determination and Assignment Procedure (FDAP). 3- Network Evaluation Procedure (NEP). Genetic Algorithm (GA) has been used for solving this problem, because of its capability for solving large and complex problems. Optimization of bus assignment to depots is another important issue in bus system planning process that has been under taken in the presented model. Finally our model has been tested on Mandl’s bus network that is a benchmark Swiss network and has been initially used by Mandl and later by Baaj and Mahmassani and Kidwai and Chakroborty and Zhao. Comparisons have shown that the model presented in this paper is superior to these past researches. Meanwhile, none of previous approaches have optimized depot assignment. Then sensitive analysis on GA parameters and discussion about calculation times has been presented. After the proposed model has been evaluated, Mashhad bus network has been designed with the presented model methodology.

Delay is one of the principal measures of performance used to determine the Level of Service (LOS) at signalized intersections and several methods have been widely used to estimate vehicular delay. Very few studies only have been carried out to estimate delay at signalized intersections under mixed traffic conditions prevailing in developing countries like India. In the present study, various problems associated with delay estimation under mixed traffic conditions in a developing country (India) and the methods to over come them were discussed and an attempt was made to improve the accuracy estimating the same. Five isolated signalized intersections from a fast developing industrial city located in TamilNadu, India were chosen for the study. Site specific PCU values were developed considering the static and dynamic characteristics of vehicles. Saturation flow was also directly measured in the field for the prevailing roadway, traffic and signalized conditions and expressed in PCU/h. Control delay was also measured following HCM 2000 guidelines. Later, this was compared with that estimated from the theoretical delay model. Even after taking several measures, good correlation between observed and predicted delay could not be obtained. Therefore, in the present scenario field measured control delay was taken into account to define LOS. A new criteria for Indian cities recently published in the literature was used to assign LOS grades of study intersections and found to be better reflecting the field conditions.

Using geotextiles to postpone reflective cracks in asphalt overlay is popular in practice, so researchers are eager to calculate its structural value. This research study has focussed on this issue for geotextiles used in the roads of Iran. Twelve sections, each examined before and after constructing the overlay, were tested from the Tehran-Qom road. The tests were of the Falling Weight Deflectometer type and at least twelve tests were carried out each time. The data from five sections (four for developing the model and one for evaluating the output) allowed a new mathematical model to be developed. For the seven remaining sections, some foreign and Iranian geotextiles were used as interlayers. The mean structural value (for all the geotextiles) was equivalent to that of a 2.67 cm-thick Hot Mix Asphalt overlay, while that for only the Iranian sections was equivalent to 2.28 cm.