http://ijce.iust.ac.ir International Journal of Civil Engineering - Journal articles for year 2006, Volume 4, Number 4 Yektaweb Collection - https://yektaweb.com en 2006/12/10 http://www.iust.ac.ir/ijce/browse.php?a_id=334&sid=1&slc_lang=en The use of Value Engineering (VE) methodology in construction industry has grown significantly, mainly in view of its extensive benefits. The main task in evaluation phase of VE workshop is to assess alternative ideas, proposed for each function. This phase of VE, hence, could be deemed as a Multi Criteria Decision Making (MCDM) problem. This paper presents a fuzzy decision support system (DSS) to be employed in evaluation phase of VE. The proposed multi alternative decision model may be recommended where alternatives’ preferences ratios are different, and scores assigned to each alternative idea are uncertain. As use of VE has greater payoffs at the earlier stages of the construction projects, in which most of the criteria are still vague and not precisely defined, exploiting this DSS may result in more tangible model of decision making process and satisfactory outlook of VE studies in construction projects. A ranking methodology in a spreadsheet template is also provided to facilitate the ranking process. Performance of the proposed methodology is tested using a case example in the tunneling industry. A. Afshar http://www.iust.ac.ir/ijce/browse.php?a_id=335&sid=1&slc_lang=en In this paper, a new Continuous Ant Colony Optimization (CACO) algorithm is proposed for optimal reservoir operation. The paper presents a new method of determining and setting a complete set of control parameters for any given problem, saving the user from a tedious trial and error based approach to determine them. The paper also proposes an elitist strategy for CACO algorithm where best solution of each iteration is directly copied to the next iteration to improve performance of the method. The performance of the CACO algorithm is demonstrated against some benchmark test functions and compared with some other popular heuristic algorithms. The results indicated good performance of the proposed method for global minimization of continuous test functions. The method was also used to find the optimal operation of the Dez reservoir in southern Iran, a problem in the reservoir operation discipline. A normalized squared deviation of the releases from the required demands is considered as the fitness function and the results are presented and compared with the solution obtained by Non Linear Programming (NLP) and Discrete Ant Colony Optimization (DACO) models. It is observed that the results obtained from CACO algorithm are superior to those obtained from NLP and DACO models. M.H. Afshar http://www.iust.ac.ir/ijce/browse.php?a_id=336&sid=1&slc_lang=en This study evaluates two different types of techniques for concrete hollow-block sections reinforced with traditional steel rebars and wire meshes, and compares their structural behaviour to that of an ordinary reinforced concrete beam section. The comparisons are based on the responses both before and after they were repaired with glass fibre reinforced polymers (GFRP). The specimens were subjected to concentrated loading up to initial failure. After failure, the specimens were repaired and loaded once again until ultimate failure. It was shown that the success of the repair by GFRP depended on the mode of failure of the hollow-block concrete beams. F.M. Wegian http://www.iust.ac.ir/ijce/browse.php?a_id=337&sid=1&slc_lang=en Analysis and prediction of structural response to static or dynamic loading requires prediction of concrete response tovariable load histories. The constitutive equations for the mechanical behavior of concrete capable of seeing damage effects or crack growth procedure under loading/unloading/reloading was developed upon micro-plane framework. The proposed damage formulation has been built on the basis of five fundamental types of stress/strain combinations, which essentially may occur on any of micro-planes. Model verification under different loading/unloading/reloading stress/strain paths has been examined. The proposed model is capable of presenting pre-failure history of stress/strain progress on different predefined sampling planes through material. Many of mechanical behavior aspects happen during plasticity such as induced anisotropy, rotation of principal stress/strain axes, localization of stress/strain, and even failure mechanism are predicted upon a simple rational way and can be presented. S.A. Sadrnejad http://www.iust.ac.ir/ijce/browse.php?a_id=338&sid=1&slc_lang=en Explosion has always been regarded as one of the most complicated engineering problems. As a result, many engineers have preferred rather simplified empirical approaches in comparison to extremely complex deterministic analyses. In this paper, however, a numerical simulation based on the combined finite/discrete element methodology is presented for analyzing the dynamic behavior of fracturing rock masses in blasting. A finite element discretization of discrete elements allows for complex shapes of fully deformable discrete elements with geometric and material nonlinearities to be considered. Only a Rankine strain softening plasticity model is employed, which is suitable for rock and other brittle materials. Creation of new lines/edges/bodies from fracturing and fragmentation of original objects is systematically considered in the proposed gas-solid interaction flow model. An equation of state is adopted to inexpensively calculate the pressure of the detonation gas in closed form. The model employed for the flow of detonation gas has resulted in a logical algorithmic procedure for the evaluation of spatial distribution of the pressure of detonation gas, work done by the expanding gas and the total mass of the detonation gas as functions of time indicating the ability of model to respond to changes in both the mass of explosive charge and the size of the solid block undergoing fracture. Rock blasting and demolition problems are amongst the engineering applications that are expected to benefit directly from the present development. The results of this study may also be used to provide some numerical based reliable solutions for the complex analysis of structures subjected to explosive loadings. S. Mohammadi http://www.iust.ac.ir/ijce/browse.php?a_id=339&sid=1&slc_lang=en The objective of this paper is to present a new method for protecting the lives of residents in catastrophic earthquake failures of unreinforced masonry buildings by introducing some safe rooms within the buildings. The main idea is that occupants can seek refuge within the safe rooms as soon as the earthquake ground motions are felt. The information obtained from the historical ground motions happened in seismic zones around the globe expresses the lack of enough safety of masonry buildings against earthquake. For this potentially important reason, an attempt has been made to create some cost-effective seismic-resistant areas in some parts of the existing masonry buildings, which are called safe rooms. The practical method for creating these areas and increasing the occupant safety of the buildings is to install some prefabricated steel frames in some of their rooms or in their halls. These frames do not carry any service loads before earthquake. However, if a near field seismic event happens and the load bearing walls of the building destroy, some parts of its floors, which are in the safe areas, will fall on the roof of the installed frames consequently, the occupants who have sheltered in the safe rooms will survive. This paper expresses the experimental and theoretical work executed on the steel structures of the safe rooms for bearing the shock and impact loads. Finally, it was concluded that both the strength and displacement capacity of the steel frames were adequate to accommodate the distortions generated by seismic loads and aftershocks properly. M. Mazloom